Graphing Lesson Part 2 – "Crest to Crest"

By Steve Goddard

Earlier in the month I wrote an article showing the trend in Arctic ice since 2002.

I took a lot of criticism from people for not measuring “crest to crest or trough to trough.

Any one schooled in analysis of cyclical data would know that one must go from crest-to-crest or trough-to-trough, to maintain some semblance of symmetry about the x-axis.

It is time now to see how serious people are about their belief systems. We have passed the 2010 El Niño peak, and can see what the “real” trend is since the cyclical El Niño peak of 1998.

http://www.woodfortrees.org/plot/rss/from:1998/last:2010/plot/rss/from:1998/last:2010/trend

Hansen claims :

“Global warming on decadal timescales is continuing without let-up … we conclude that there has been no reduction in the global warming trend of 0.15-0.2C/decade that began in the late 1970s.”

Talk about cherry-picking! Look at his start point. He chose the worst case trough to crest to measure his trend.

Question for readers. Is Hansen correct, or does he need some serious graphing lessons? Below are the trend graphs from 1998-present for all four sources. GISS is way out of line.

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152 thoughts on “Graphing Lesson Part 2 – "Crest to Crest"

  1. Good one, Anthony.
    The nattering nabobs of negavity were just getting wound up nice & tight about global cooling back in the 1970’s then the climate shifted to the warm side of a multi-decadal cycle and after 20 years of that got wound up even tighter about global warming.
    Thirty years is not enough time to mark permanent or even long term climate change. It’s essentially still just weather.
    Thirty years is however enough to make a substantial fraction of the population have no memory of what it was like when the climate was in a cooling mode.
    It enough to make me long for a return to the days when man-made global castrophe was all about nuclear winter and everyone was interested in bomb shelters in their basements and air raid sirens got tested regularly. In retrospect – good times.

  2. Steve!
    Thanks again for a good article.I`ve been in touch with DMI and checked the facts that was published here on WUWT from the the e-mail correspondence with them.
    Its really a BIG SCANDAL that has to be monitored. The discrepancy between DMI and GISS has to be explained it can not be allowed to fade. Its just NOT acceptable.
    This is without a very good explaination a PROOF of misconduct on behalf of GISS or DMI. And I can’t or will not rest until this matter is settled, neither should you.
    This has to be brought to the public and authorities’ attention because this really bites!! We don’t have any FOX tv in Sweden; MSM and public service is completely WWF/Greenpeace loyal.
    Has any media in the US covered this four degree gap DMI/NASA?
    Swedish goverment public service is an embarrasment and just Wednesday on prime newstime they argued that floods in China were due to “climate change” and that it was hotter and worse than ever. If you are sceptic to the BBC …..well you should try the Swedish SVT!!! That’s a REAL climate propaganda center.

  3. I thought that Jones had explained the a period of less than fifteen years was too short to determine a statistically significant trend, if he’s right the debate is moot.
    Perhaps we could argue over how many fairies can dance on the head of a pin instead.

  4. Maybe I got up too early this morning & am suffering from a case of the stupids, but why is the RSS trend line in the second graph different from the RSS trend line in the fourth graph?

  5. I’ve been struck by this 30 year meme for awhile, and what I notice is that it is the length of one of the phases of the PDO. I noticed this when arguing about trends, and the lovely irony is that if you decide at the end of one of those phases that the last 30 years have marked a trend, then you are going to be wrong about the next 30 years.
    There’s truth in the 30 year meme, as well as built in deception.
    =============

  6. If the temperature has relatively low frequency, periodic fluctuations plotting a trend line is a highly dubious exercise.

  7. RC Saumarez
    Is your criticism directed at Hansen or me? He is the one who said:

    we conclude that there has been no reduction in the global warming trend of 0.15-0.2C/decade

    You should write him and tell him that his conclusion is highly dubious.

  8. There is a deal of nonsense talked about these graphs, isn’t there ?
    I mean Look at the Y-axis, what is the shift on the scale ?
    It is less than a degree centigrade, sometimes much less.
    Prof Lindzen has much to say about that in his CEI lecture.
    Find it on my website video wall (Dr. Lindzen of MIT, disputes …… )
    http://fraudulentclimate.atspace.com/

  9. stevengoddard says:
    July 31, 2010 at 4:01 am
    “Leon,
    You are correct. The last graph is to the start of 2010, not the present. I asked the moderator to replace it with the equivalent graph
    http://climateinsiders.files.wordpress.com/2010/07/trend.png
    Wood for trees has a different meaning in their to: and last: fields
    [Fixed. ~dbs]”
    Ok, now my turn, I haven’t had my morning coffee yet, but the trends are still different. Que tal?

  10. Years ago, I was warned about using peaks or troughs. For my quick ‘napkin’ climate model, I used the mid point of the warming periods to find that once the natural background warming and solar influence of 0.15C are removed, there is only 0.08 C of warming to be attributed to other causes like decreased volcanic activity and CO2 warming for the 1930 to 1990 period. — John M Reynolds

  11. And you guys do know if you leave the “To” or “last” blank, woodfortrees will go to the last available data.

  12. John M Reynolds
    In the ice graph, I did midpoint-to-midpoint and everyone said that was wrong. They said that it needs to be peak-to-peak. Now the criticism is that I am doing peak-to-peak when I should be doing midpoint-to-midpoint. LOL
    Hansen does trough to peak (which is obviously bogus) and gets it through peer-review no problem.
    Just goes to show what a joke “climate science” is. It doesn’t even vaguely resemble a serious science.
    “lies, damned lies, and statistics”

  13. At any rate, using either trend line, we can see GISS is so out of touch with reality, I like to apologize to the world on behalf of the climate research I’ve helped fund with the GISS and NASA altogether. Hopefully, at some point, they’ll decide to quit being an embarrassment to this nation and go back to what once made them a great unit, space exploration.

  14. Sorry _ I’ve just noticed a typo (0.02 should have been 0.20 for 1979). Please post this corrected version if possible.
    Here are the rolling ten year average global temperature anomalies, (in degrees CelsiusX100), for the preceding ten years from the NASA GISS Series. Anomalies are relative to the average for 1951-1980 and should be divided by 100 to get the anomaly in degrees Celsius.
    Year ten year anomaly
    1979 0.20
    1980 1.70
    1981 5.30
    1982 5.80
    1983 7.00
    1984 8.70
    1985 9.60
    1986 12.50
    1987 13.80
    1988 16.80
    1989 17.80
    1990 19.80
    1991 20.70
    1992 21.50
    1993 20.30
    1994 21.70
    1995 25.00
    1996 26.60
    1997 28.00
    1998 30.50
    1999 31.80
    2000 31.30
    2001 32.60
    2002 36.90
    2003 41.00
    2004 43.50
    2005 46.00
    2006 48.50
    2007 50.20
    2008 48.90
    2009 50.78
    [figures derived from:
    http://data.giss.nasa.gov/gistemp/tabledata/GLB
    with the annual mean J-D (January-December) figures averaged over the previous ten year periods, eg the 1979 0.20 figure is the average of +3 -10 0 +14 -8 -4 -16 +13 +1 +9 derived from the J-D years 1970-1979 inclusive. ie That is the average anomaly for the 1970s]
    Thus the decadal increase in average global land/ocean surface temperature reported is:
    1970s to 1980s (17.80 – 0.20)/100 = 0.1760C
    1980s to 1990s (31.80 – 17.80)/100 = 0.1400C
    1990s to 2000s (50.78 – 31.80)/100 = 0.1898C
    (I have reported the figure to 4 sig. figs. just to aid checking of arithmetic – 2 sig. figs. would be more appropriate).
    Thus, Hansen’s claim that, “that there has been no reduction in the global warming trend of 0.15-0.2C/decade” is entirely supported by the NASA GISS global land/sea surface temperature series.

  15. It’s 5 am here (covering myself!) but using the highly sophisticated squint test, the RSS trend line is light green in the second chart, and light purple in the last chart. The scales are a little different, and the start point/value for RSS in the last chart is slightly lower, but the trend looks roughly the same.
    But make no mistake, it’s still worse than we thought/Polar bears doomed/end is still nigh, so fear not.

  16. Both the Canadian Annual temperature departures and US Contiguous annual temperature charts actually both show a decline since 1998

  17. Being an Historian rather than a Scientist, and having little Math, I cannot criticize but I can critique! We can choose, in history, which starting point, which event, which person, to use and go from there – and get similar results. And we also have our revisionists, the Michael Manns, of history, and sometimes they become the new CW if they have the data to back them up.
    Enough of that. What I do NOT understand is why the charts ALWAYS are so dramatic unless it is for PR purposes (or simply to emphasize a point). Why not show temperature differences in 1, 2, 5, or 10 degree differences? To most of us laymen, 6% of a degree is meaningless. In everyday life we deal with actual degrees, not percents of them.
    Thorncraft

  18. So, while you guys are sorting this out, I went to woodfortrees and did the trends myself, without the offsets. I’m struck by something I don’t understand, and maybe it is just a coincidence. You’ll note, HadCrut’s variance adjusted trend from 1998 and RSS’s is nearly identical. As we’ve noted, GISS’ slope is, well, dramatic. But, UAH’s trend is the one most closely resembling GISS.(though UAH’s is still closer to HadCrut’s than GISS) But this is counter-intuitive to me. One satellite and the other a “hard” read. (RSS and HadCrut.) And then again one satellite and another “hard” read. (UAH and GISS)…..WUWT?
    http://www.woodfortrees.org/plot/rss/from:1998/trend/plot/gistemp/from:1998/trend/plot/uah/from:1998/trend/plot/hadcrut3vgl/from:1998/trend

  19. Last graph: GIStemp appears to be the trend leader, eh? Unfortunately, this isn’t a fashion show.
    (Gosh! Look at all those tiny numbers on the vertical axis of the LHS of the last graph. Combine the four trends and put the max/min error bars from the set of trends on the results and poof! the alarm goes away.)

  20. Well, if the last three temperature graphs were turned in by my students in my intro. physics course, and conclusions drawn from such graphs, the students would not be happy with their grades.
    All three graphs have different scales on the y-axes, and thus do not show the same relative change in the temperature variable. This is one aspect of climate science that drives me up a wall: the use of changing scales on the y-axis in order to deceive. The first two graphs go from -0.2 to 0.9, and -0.4 to 0.6 respectively. Close, but if plotted on the same scale would still look different. The third graph with the trend lines is absurd with a scale a factor of almost 10 differrent from the other two. If that graph was also plotted on the same scale as the temperature anomaly data, then all 4 of the lines would be essentially flat. I understand the point was to show how the GISS line is “out of whack”, but to me what it really shows is that this temperature trends are really much ado about nothing if plotted correctly.
    How about a WUWT policy that all temperature anomaly graphs will use the same y-axis scale so we can really compare data properly???

  21. You have to consider the physical properties of the climate system. We know that ENSO is one of the major causes of interannual variability in global average temperature. On a scale of several years, any such temperature series is going to be dominated by these fluctuations, and to a lesser extent by the solar cycle. Over longer periods, these fluctuations average out, so we see more of the sustained forcings from changes in TSI, long-lived greenhouse gases, aerosols and so on. 30 years is long enough to distinguish a trend from the ‘noise’ of the interannual variability, which tends to average out to zero. Therefore Dr. Hansen is right to point out that the current global warming of 0.15 – 0.2°C per decade shows no sign of slowing down at present.

  22. @ Kim
    Ah, but guess how many years Hansen relied on for his Congressional testimony in 1988 🙂
    That’s right. Just enough to establish the trend he desired.

  23. WHAT IS IPCC’S EXAGERATION FACTOR?
    IPCC
    For the next two decades, a warming of about 0.2 deg C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1 deg C per decade would be expected.
    http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-projections-of.html
    OBSERVED DATA (CRU)
    A warming of about 0.03 deg C per decade
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1990/to:2000/plot/hadcrut3vgl/from:1990/to:2000/trend/plot/hadcrut3vgl/from:2000/to:2010/plot/hadcrut3vgl/from:2000/to:2010/trend
    CONCLUSION
    IPCC’s EXAGERATION FACTOR IS 6.7 (=0.2/0.03)!

  24. The whole 30 year meme was an arbitrary pick because it was easier to compute then a 35 year one, well at least that is what Phil Jones says:

    From: Phil Jones
    To: “Parker, David (Met Office)” , Neil Plummer
    Subject: RE: Fwd: Monthly CLIMATbulletins
    Date: Thu Jan 6 08:54:58 2005
    Cc: “Thomas C Peterson”
    Neil,
    Just to reiterate David’s points, I’m hoping that IPCC will stick with 1961-90.
    The issue of confusing users/media with new anomalies from a
    different base period is the key one in my mind. Arguments about
    the 1990s being better observed than the 1960s don’t hold too much
    water with me.
    There is some discussion of going to 1981-2000 to help the modelling
    chapters. If we do this it will be a bit of a bodge as it will be hard to do
    things properly for the surface temp and precip as we’d lose loads of
    stations with long records that would then have incomplete normals.
    If we do we will likely achieve it by rezeroing series and maps in
    an ad hoc way.
    There won’t be any move by IPCC to go for 1971-2000, as it won’t
    help with satellite series or the models. 1981-2000 helps with MSU
    series and the much better Reanalyses and also globally-complete
    SST.
    20 years (1981-2000) isn’t 30 years, but the rationale for 30 years
    isn’t that compelling. The original argument was for 35 years around
    1900 because Bruckner found 35 cycles in some west Russian
    lakes (hence periods like 1881-1915). This went to 30 as it
    easier to compute.

    Personally I don’t want to change the base period till after I retire !
    Cheers
    Phil
    At 09:22 05/01/2005, Parker, David (Met Office) wrote:

    http://www.eastangliaemails.com/emails.php?eid=462&filename=1105019698.txt

  25. GISS/NASA in general and the ineffable Hansen in particular have exactly zero credibility. Whatever minuscule factual basis such pseudo-scientific Cargo Cultists’ propaganda exhibits, its deceitfully manipulated, skewed “adjustments” render it utterly worthless by any objective or even rational standard.
    As time goes on and Nature takes her course (we await Winter 2011 with trepidation), Hansen’s Green Gang will only wax ever more vociferous. But Luddite sociopaths’ bleats and squeaks themselves are unsustainable. As Earth tips into a 70-year “dead sun” Maunder Minimum similar to that of 1645 – 1715 while our current 12,250-year Holocene Interglacial Epoch is decades overdue to end, “climate change” will represent not Global Warming but a ferocious resurgence of Ice Time.

  26. In response to Steve Goddard:
    I’m not criticising you. I’m merely pointing out that if you have multiple periodicities in data, as apperas to be the case in temperature, forcing linear trends on a time series may be misleading. What appears to be a short term linear trend may be simply a low frequency component of cyclical change. As with many time series problems, a hypothesis about the behaviour of that data suggests appropriate analysis techniques and these may have underlying physical interpretation. If you believe that temperature is on a linear upward path, a linear model is appropriate; if you think temperature varies with a cyclical model, there are better ways of analysing such data.
    While I could write to Dr Hansen, I feel that he is unlikely to take much notice of what I have to say.

  27. A few months ago I said to a person (who is a “believer” in AGW) that the mean global temperature did not increase since about the year 2001. He replied that this proves nothing, that there have been similar, and even longer, non-warming periods in the past (for example from 1940 to 1970), and that the general trend (since 1900) is warming.
    Any comments?

  28. Hansen Claims
    “Global warming on decadal timescales is continuing without let-up … we conclude that there has been no reduction in the global warming trend of 0.15-0.2C/decade that began in the late 1970s.”
    Steve Goodard asks
    Is Hansen correct, or does he need some serious graphing lessons?
    The honest answer is that we don’t know. If the NULL (default) hypothesis is that warming is continuing at ~0.15 deg per decade then the data would not support rejection of it. As I pointed out on another thread a decade is too short a period to draw any conclusions. Simply lengthening/shortening the period by a few months changes the sign of the UAH trend. We need at least 5 more years before any conclusions can be drawn.

  29. It is time now to see how serious people are about their belief systems. We have passed the 2010 El Niño peak, and can see what the “real” trend is since the cyclical El Niño peak of 1998.
    Steve
    I don’t think there’s anything Hansen can teach you about “cherry picking”. I notice the “real” is the rss trend which just happens to be the lowest trend.
    Beautiful!

  30. That trend graph doesn’t look right to me. The labeled trends in the legend compared to what’s plotted in the graph look off. Just me?

  31. Jean Meeus said (July 31, 2010 at 7:33 am):

    A few months ago I said to a person (who is a “believer” in AGW) that the mean global temperature did not increase since about the year 2001. He replied that this proves nothing, that there have been similar, and even longer, non-warming periods in the past (for example from 1940 to 1970), and that the general trend (since 1900) is warming. Any comments?

    Natural interannual fluctuations in global average temperature, due mainly to ocean circulation (such as ENSO, the El Niño Southern Oscillation) and the 11-year solar cycle, are on a scale of around 0.2°C. Longer term changes due to forcings from changes in TSI, greenhouse gases and aerosols are on a scale of around 0.2°C per decade – i.e. the natural and regular fluctuations can easily mask a decade or more of a long-term warming or cooling trend. That’s why a graph of global average temperature over a 9-year period can *only* be showing us natural interannual variability, not a long-term trend. If anyone draws a flat trendline through 9 years of data and claims that that proves there is no warming trend, they’re lying. We could just as easily draw a trendline through a different 9 years and get 0.5°C of warming per decade, and that would be equally false. The actual warming trend is currently around 0.18°C per decade.

  32. John Finn says:
    July 31, 2010 at 7:39 am
    a decade is too short a period
    It was warmer on earth during the Medieval Warm Period. That was ~1000 years ago.

  33. Jean Meeus
    It is not adequate for people to say “the earth is warming.”
    The fact is, it is warming much slower than the climate models forecast, indicating that climate sensitivity to CO2 is much lower than alarmists have been telling politicians.

  34. John Finn said (July 31, 2010 at 7:39 am):

    …As I pointed out on another thread a decade is too short a period to draw any conclusions. Simply lengthening/shortening the period by a few months changes the sign of the UAH trend. We need at least 5 more years before any conclusions can be drawn.

    Hansen’s conclusion is based on 30 years of data. Isn’t that enough?

  35. Jean Meeus says:
    July 31, 2010 at 7:33 am
    A few months ago I said to a person (who is a “believer” in AGW) that the mean global temperature did not increase since about the year 2001. He replied that this proves nothing, that there have been similar, and even longer, non-warming periods in the past (for example from 1940 to 1970), and that the general trend (since 1900) is warming. Any comments?
    Yes, I have one comment. It demonstrates that the warming before 2001 is a natural behavior of Earth’s climate. These climatic changes have happened always since those times when the Earth got cooler after its accretion process finished; the same behavior applies to any warming and to any cooling. It’s natural, normal, expected… Natural processes have nothing to do with any “forcing”. Actually, the warming that we underwent in the 90s was pretty benign in comparison with other warming periods in the geological past. The Holocene has seen increases of temperature of almost 6 degrees.

  36. Jean Meeus says:
    July 31, 2010 at 7:33 am
    […] “and that the general trend (since 1900) is warming.
    Any comments?”

    The general trend coming out of the Little Ice Age has been towards warming. Why did we start the warming before SUVs, Coca-Cola, and Big Oil?
    Where’s the ‘A’ in GW? I can see the ‘A’ in AUW (Anthropogenic Urban Warming) but beyond that, I’ve not seen convincing evidence of anything but natural GW. “And that’s a good thing.” (Best Martha Stewart voice, that was.)

  37. Both Slioch and Icarus try to bleed pre-1998 warming into the recent years. Both are simple statistical tricks. Sorry guys, you get an F on the question … has been any warming in the last 12 years?
    Of course, we can’t assume the trend of the last 12 years means anything either. It just is what it is. And, since we are heading into a La Niña, it’s very likely the trend will only decrease in the next year and possibly the following year. That would make 14 years without an increase in temperatures.
    I believe Phil Jones was once quoted as saying 15 years of no warming would falsify AGW. It will probably take a record breaking El Niño by 2013 or the situation Jones mentioned will have occurred.
    All that said, the real question of the true influence of CO2 emissions will probably be unknown for decades. We simply don’t have a solid base of knowledge to base any climate theory on.

  38. Girma said:

    IPCC’s EXAGERATION FACTOR IS 6.7 (=0.2/0.03)!

    You’re taking a projection for the trend of the *next* two decades and using data from the *previous* decade to disprove it? That’s clearly absurd, even ignoring the fact that a decade of data cannot possibly show us a long-term trend. You will have to wait about 20 years before you can say anything at all about how accurate that projection was.

  39. Mike Monce is absolutely right. The function of a graph is to draw a picture (for simple people like me) of mathematical information. If we wish to compare graphs we need the x and y axis made to the same scale. Maybe there’s some software out there that would do this readily?

  40. Jean Meeus: “He replied that this proves nothing, that there have been similar, and even longer, non-warming periods in the past (for example from 1940 to 1970), and that the general trend (since 1900) is warming.
    Any comments?”
    Only to say that we know that any warming from 1900 to about 1970 was not caused by green house gases.

  41. Jean Meeus 7:33 am
    Where I live was covered with ice 10,000 years ago. It has been warming since then.
    Where I live suffered through drought 75 years ago. It is cooler now than it was then.
    To be an AGW believer requires selecting a convenient starting point, setting aside the other drivers of temperature variance, ignoring the creeping biases in the measurement and reporting of temperatures, and blaming CO2 for the resulting trend in the graphs.
    Sounds like a pretty solid basis for global policy-making to me…what do you think?

  42. This post seems confused on a number of points.
    1. For a cyclical and regular time series, even measuring trends peak-to-peak or trough-to-trough is not meaningful. See here
    2. El Niño is not a cyclical phenomenon. It is quasi-periodic. Its amplitude varies enormously. The 1997-8 one was considerably larger than the most recent one.
    3. Global temperatures are not cyclical either. The instrumental record has no “trough” to measure any trend from. The late 1970s saw a clear change in climate trends – to measure something from a point of clear change cannot be described as cherry picking. In any case, for every year in the record for which you can derive a statistically significant trend from that year to the present, the trend is positive.
    4. 1998 to present is too short to measure statistically significant trends, and too short for variations between datasets to be considered significant. If you are worried about outliers, you should look at a longer trend – like since the change in climate trend in the late 1970s.

  43. ” John Finn says:
    July 31, 2010 at 7:39 am
    Simply lengthening/shortening the period by a few months changes the sign of the UAH trend. We need at least 5 more years before any conclusions can be drawn.”
    For the UAH linear trend of monthly means from peak (1998) to peak (2010) I get 0.0003°C per month or 0.036°C per decade. The positive sign might be a result of the fact that temperatures drop so sharply after El Niño. We will see in a few month if the trend from trough to trough is negative.
    But waiting a few years will almost certainly result in a negative trend from peak 1998.

  44. A reasonable comparison is to pull-out the variability caused by the ENSO. The 1997-98 El Nino was a little bigger than the last one was. (I also take into account the AMO since it’s impact is similar to the ENSO. Today’s AMO values are very high, about the same as they were at this time in 1998).
    When these are taken into account, we find GISTemp is increasing at about the same rate it has always increased at. This rate though is much lower than predicted and will only get us about half-way to the projected warming of 3.25C by 2100.
    Here is GISS since Feb 1998 (adjusted for the ENSO and AMO) versus the most current prediction of the IPCC in AR4 (under the A1B CO2 scenario which seems to be very close to the trends to date).
    http://a.imageshack.us/img821/8305/gisspeak1998.png
    Here is nice big chart of the IPCC AR4 predictions put up by Lucia. (Even in the year 2000, their back-cast models using temperature data up to that time were too high by 0.2C or so and they would now be too high by about 0.32C).
    http://rankexploits.com/musings/wp-content/uploads/2008/08/compare-to-copenhagen.jpg

  45. I think a random noise signal should not have any component with a wavelength longer than the resolution. It is very easy to say that short term variations are natural variations which will disappear with a 30 years average. And long term variations are in fact climate feedback with a constant trend.
    I thought there was a standard scientific method to analyze a signal you think might be random noise. I thought a settled science built by thousands of scientists should have a clear explanation for all natural variations and the absence of long term natural variations when the record is full of it.

  46. Gavin’s Goalposts
    Gavin Schmidt of NASA has a website called RealClimate. A couple of years ago there was a post on signs of climate change.
    http://www.realclimate.org/index.php/archives/2007/12/a-barrier-to-understanding/
    In the discussion thread Daniel Klein asks at #57:
    OK, simply to clarify what I’ve heard from you.
    (1) If 1998 is not exceeded in all global temperature indices by 2013, you’ll be worried about state of understanding
    (2) In general, any year’s global temperature that is “on trend” should be exceeded within 5 years (when size of trend exceeds “weather noise”)
    (3) Any ten-year period or more with no increasing trend in global average temperature is reason for worry about state of understandings
    I am curious as to whether there are other simple variables that can be looked at unambiguously in terms of their behaviour over coming years that might allow for such explicit quantitative tests of understanding?
    [Response: 1) yes, 2) probably, I’d need to do some checking, 3) No. There is no iron rule of climate that says that any ten year period must have a positive trend. The expectation of any particular time period depends on the forcings that are going on. If there is a big volcanic event, then the expectation is that there will be a cooling, if GHGs are increasing, then we expect a warming etc. The point of any comparison is to compare the modelled expectation with reality – right now, the modelled expectation is for trends in the range of 0.2 to 0.3 deg/decade and so that’s the target. In any other period it depends on what the forcings are. – gavin]

  47. The key words in the criticism you received were “sinusoidal data”. Your graph was sinusoidal, Hansen’s graphs are not!

  48. A little discipline is needed when filtering noisy and/or cyclic data:
    1. A way to to deal with end effects is to “window” the data. This also makes point 2 dramatically apparent – current data has little influence.
    2. A moving average (or other symetrical filter method) is an estimate for the actual value of the data at the centre of the averaging period, not the end. Filtered data should be time-shifted to display correctly.
    Are either of these methods used on climate data?
    MG

  49. Jean Meeus says:
    July 31, 2010 at 7:33 am
    Not the Jean Meeus of ‘Astronomical Algorithms’, I presume? Or, just a pseudonym? On the unlikely chance that it is the same, thanks for a very useful book.
    Icarus says:
    July 31, 2010 at 8:23 am
    “Hansen’s conclusion is based on 30 years of data. Isn’t that enough?”
    Based on what? What if there is a strong 60-ish year cycle in the data? (There is, BTW.)

  50. Steve,
    You must be enjoying this thread immensely.
    You invite readers to observe the GISS data from 1880 to 2010, note Dr. Hansen is quoted drawing significance from the period late 1970s to present, and ask your readers “Is Hansen correct, or does he need some serious graphing lessons?”.
    Well, it is as obvious as the proverbial dogs balls that Dr. Hansen references a “trough to crest” period in the data. Which, as per the background context you provided, makes the critique of your analysis on an earlier thread – you used mean to mean – trivial.
    Not one of the comments – particularly not one of the comments from the warming-fast side – answers your question. Most of the discussion focuses on the last 10 or 12 years. Some explores the necessary minimum period, concluding correctly that 30 years is not enough (which is true, but you were looking for a simpler observation).
    So let me be the first: any information from wandering data (I avoid the term cyclical, since that term implies a regularity not present in climate data) must be crest to crest or trough to trough or mid to mid. Since we are currently at a crest in the GISS data presented above, the only acceptable periods ending in 2010 would be 1940 to 2010 or 1900 to 2010. Anything else is intellectually dishonest.

  51. RW says:
    July 31, 2010 at 8:45 am
    “2. El Niño is not a cyclical phenomenon. It is quasi-periodic. Its amplitude varies enormously. The 1997-8 one was considerably larger than the most recent one.”
    An amplitude modulated signal is not periodic? Allow me to introduce you to a guy named Fourier.

  52. Icarus
    You wrote, “You will have to wait about 20 years before you can say anything at all about how accurate that projection was.”
    If you compare the global warming rate for the last four decades, you see a definite deceleration for the last period from 2000 to 2010 as shown here:
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1970/to:1980/plot/hadcrut3vgl/from:1970/to:1980/trend/plot/hadcrut3vgl/from:1980/to:1990/plot/hadcrut3vgl/from:1980/to:1990/trend/plot/hadcrut3vgl/from:1990/to:2000/plot/hadcrut3vgl/from:1990/to:2000/trend/plot/hadcrut3vgl/from:2000/to:2010/plot/hadcrut3vgl/from:2000/to:2010/trend
    As a resutl, IPCC’s Exageration Factor is 6.7!

  53. GLOBAL MEAN TEMPERATURE CYCLES
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1880/to:2010/compress:60/detrend:0.775/offset:0.518/plot/hadcrut3vgl/from:1880/to:2010/trend/detrend:0.775/offset:0.518
    The above graph for the data from CRU shows the following periods for relative global cooling and warming phases:
    1) 30-years of global cooling from 1880 to 1910
    2) 30-years of global warming from 1910 to 1940
    3) 30-years of global cooling from 1940 to 1970
    4) 30-years of global warming from 1970 to 2000
    If this pattern that was valid for 120 years is assumed to be valid for the next 20 years, it is reasonable to predict:
    5) 30-years of global cooling from 2000 to 2030
    The above graph also provides the important result that the years 1880, 1910, 1940, 1970, 2000, 2030 etc are (Global Mean Temperature Anomaly) GMTA trend turning points, so meaningful GMTA trends can be calculated only between these successive GMTA turning point years.
    Here are then the global warming rates for the last 100 years:
    Global warming from 1910 to 1940 => +0.15 deg C per decade
    Slight global cooling from 1940 to 1970 = -0.03 deg C per decade
    Global warming from 1970 to 2000 => +0.16 deg C per decade
    Slight global warming from 2000 to 2010 => +0.03 deg C per decade
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1940/compress:12/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1970/to:2000/compress:12/plot/hadcrut3vgl/from:1970/to:2000/trend/plot/hadcrut3vgl/from:1940/to:1970/compress:12/plot/hadcrut3vgl/from:1940/to:1970/trend

  54. @RW
    Showing a 30 year trend as being strongly positive and with agreement between the various sources while the 10 year trend in the main post shows different results simply reinforces the idea that trends should be regarded with considerable suspicion as the data clearly deviates from a linear trend.
    As regards using the peak or trough of the trace, surely we are interested in the way that the mean temperature varies, i.e. a zero-phase, low pass filtered version of the signal. While the smoothing using a rectangular average creates something nearer to an integral of trace, it is not ideal for many reasons. There is substantial theory underpinning near-optimal filters. When these are constructed auto-regressively, much more useful responses can be obtained withough having to employ long impulse responses as in the case of a moving average filter so that there isn’t a “dead zone” at the beginning and end of the record.

  55. The reality is, statistically speaking, the temperature record is totally consistent with a warming of 1°C/century. There is a 60-years cycle, see Girma’s comment. And the 90s are about the most warming you can expect in a 10-years period. The latter led to exaggerated claims about climate sensitivity. I challenge anyone to prove that 1°C of warming per century is impossible considering the well known 60-years cycle.

  56. The now common practice of extrapolating “trends” into the distant future is as unscientific as unscientific can become. My college professors in chemistry and physics all discussed this matter with their students, and each and all said, “Never do it”.
    Of course, that was back in the 1950s. Wise college professors back then.

  57. If all the natural variation is explained by scientific literature in a quantifiable way, simply remove it all from the trend and show us what is left over as unexplained warming. Just because the trend is X/decade (4X for GISS), doesn’t mean you have successfully explained how much warming is coming from CO2. The natural variability should be removed from the trend. Of course, if anyone does this, they will need to list each component of variability, and then quantify how much was subtracted from the trend. It is the only way to say anything one way or the other about AGW.

  58. Re: Icarus, link to temperature graphs with 3 to 22 year rolling trends.
    The 1978 to present 0.18C*/decade trend is certainly clear. What happens when you do that for the 1850 to 1978 period?
    And 0.18C*/decade is certainly not catastrophic, and, I understood, not indicative of pCO2 forcing (with H2O enhancement). If water enhancement exists, does this last 30-year consistency of 0.18C*/decade trend not mean that CO2 forcing is really something like 0.06C*/decade? Do any of this last 30-year trend support the IPCC model of CO2/H2O forcing and catastrophic, i.e. 3-5*C/100 year global warming from fossil fuel usage?
    Each time I refocus on the times of supposed AGW, i.e. after 1965, I bump into a contradiction in temperature increase and the disaster model used to justify the CO2 tax and punish program. Am I missing something here? Where is the data or observation that supports the model?

  59. Girma: 10 years can only ever show you the natural interannual variability, not the trend, because that variability is ~0.2C from year to year, and the trend is ~0.2C per decade. In other words, interannual variability can completely mask the long term trend in any 10 year period. Make sense?

  60. ” Icarus says:
    July 31, 2010 at 11:16 am
    …variability is ~0.2C from year to year, and the trend is ~0.2C per decade. In other words, interannual variability can completely mask the long term trend in any 10 year period. Make sense?”
    What does not make sense is the fact that Hansen observes the trend of 0.2°C per decade (for 1998 to 2009), whereas Jones or Spencer do not.

  61. Bart: El Niño is not periodic. It is quasi-periodic, occurring at intervals typically of 2-7 years.
    RC Saumarez: “trends should be regarded with considerable suspicion as the data clearly deviates from a linear trend” – well, certainly the trend may not be linear, but we could avoid all sorts of misinterpretation problems if no trend was ever plotted without the ±1σ trend lines also marked.

  62. Graphing lessons won’t help Hansen. His choice of 1880 is a cherry-pick, he knows it, and this is all about handing over something to rubber-stamp as “proof of global warming”.
    November has a chill in it already.

  63. When I look at the long term HADCRUT and superimpose a linear trend on that, it shows a 0.7 rise over the 160 years. However that is with 3 peaks and 2 troughs of a lumpy sine wave, which correlates very closely with the PDO cycles, and could be said to be entirely attributable to natural variation.
    There is every indication that we are past the beginning of a cool cycle, and if the past is any guide to the future, it is likely that we will finish this cool cycle about 0.7C below where we are now. That will drag the linear trend down to about a 0.6C rise over 180 years.
    Given we were coming out of a little ice age, I don’t think there’s anything here to be getting alarmed about. In fact, what’s strange about all this, is just how stable the climate has been when you consider all of the factors that contribute to climate change.
    Further, it is only this 0.6C rise that we can attribute anything not natural to, such as greenhouse gasses or other forcings, and that is assuming that this 180yr trend isn’t just part of a longer cycle, possibly headed down again given our weak sun.
    Dr Lindzen was right. Our descendants are going to have a good old laugh at our version of arguing over angels on pins.

  64. Just for reference, here is a table for an unofficial five-segment line-anomaly plot derived from the monthly NSIDC Arctic ice-extent data from 1978 to 2010. I created the master anomaly curve by subtracting a Fourier series representation of the average annual freeze-melt curve computed over the largest complete integer-year period.
    The interior line segment breaks were automatically optimized for best fit to the master curve.

    Segment     Segment-Dates         Values, 1000 sq-km      Slope
    Number    Start        End         Start      End      1000 sq-km/yr
      1      1978.875    1987.463      672.4     381.2         -33.9
      2      1987.463    1990.461      381.2     185.3         -65.4
      3      1990.461    2001.634      185.3    -119.9         -27.3
      4      2001.634    2007.625     -119.9   -1048.6        -155.0
      5      2007.625    2010.458    -1048.6    -529.5         183.2
    
  65. RW says:
    July 31, 2010 at 8:45 am
    “1. For a cyclical and regular time series, even measuring trends peak-to-peak or trough-to-trough is not meaningful. See here”
    It certainly is. The trend is mathematically zero. I don’t know what the woodfortrees plotter thinks it’s doing, but what it isn’t doing is calculating a linear trend over the test dataset. I hope people haven’t been using it on real data, because it’s giving nonsensical answers. The programme seems to have a serious bug in it.

  66. Alexej Buergin said (July 31, 2010 at 11:46 am):

    What does not make sense is the fact that Hansen observes the trend of 0.2°C per decade (for 1998 to 2009), whereas Jones or Spencer do not.

    Spencer’s MSU UAH shows 0.14C per decade over the full data set.
    RSS is 0.16C per decade.
    GISTEMP is 0.17C per decade.
    HADCRUT3 is 0.16C per decade.
    All from the excellent woodfortrees site.
    I do think Spencer tries hard to minimise the warming in his data series.

  67. What utter nonsense ! A hadcrut3 “trend” of 0.02 degrees in 10 years ? Where are the error bands ?
    Surfacestations.org found errors of greater that 1 degree for over 90% of stations !! This is a factor of at least 50 greater, making any such trends meaningless. Even the recording accuracy is still listed as 1 degree. ( http://www.srh.noaa.gov/ohx/dad/coop/EQUIPMENT.pdf page 11 )
    What difference does it make if the world is warming or cooling anyway ? The issue is whether man has had anything to do with it … something the IPCC and alarmists have no evidence whatsoever to support.

  68. Icarus says:
    July 31, 2010 at 8:09 am
    Jean Meeus said (July 31, 2010 at 7:33 am):
    May I be rude & ask what is the trend line since 1850??
    Me thinks you will find it comes in very close to Zip, Zero.
    regards

  69. Jean Meeus, we have two generally accepted definitions of climate change circulating. They are not the same. I discuss this in my essay “Climate Change, Just What Is That Anyway?”. To sum: “…. From Wikipedia:
    “For current global climate change, see Global warming.
    For past climate change, see paleoclimatology and geologic temperature record.
    Climate change is a change in the statistical distribution of weather over periods of time that range from decades to millions of years. It can be a change in the average weather or a change in the distribution of weather events around an average (for example, greater or fewer extreme weather events). Climate change may be limited to a specific region, or may occur across the whole Earth.” Now I can live with that as it meets all the needs of my science and I suspect others. I am sure it was written by someone knowledgeable in the scientific method and the Philosophy of Science. However, the Wikipedia authors go on to say:
    “In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate. It may be qualified as anthropogenic climate change, more generally known as “global warming” or “anthropogenic global warming” (AGW).” I guess that explains my wondering. It is clear that two different definitions are in use. This is not good. It is very much not good, because it tends to cause confusion….”

  70. @Paul Birch.
    What are you saying? If sucessive peaks are identical but the shape of a curve deviates from being a pure sinusoid, so that the integral of the sucessive curves wrt time is increased, this has no meaning – “the trend is zero”?
    This whole argument would benefit from a rather more rigorous definition of how temperature is defined as a function of time and the application of a mathematical model that recognises the complexities of the data. Fitting least squares line to a continuous signal that does not have a defined distribution is difficult to interpret and (@RW) since the distribution of the data is non-stationary, calculation of exact confidence limits is problematic.

  71. paulhan said (July 31, 2010 at 1:35 pm):

    When I look at the long term HADCRUT and superimpose a linear trend on that, it shows a 0.7 rise over the 160 years.

    What does that tell us? Not very much, considering that important forcings over that period, such as TSI and well-mixed greenhouse gases, are not changing linearly.

    However that is with 3 peaks and 2 troughs of a lumpy sine wave, which correlates very closely with the PDO cycles, and could be said to be entirely attributable to natural variation.

    The great increase in atmospheric CO2 over that period is not a natural variation.

    There is every indication that we are past the beginning of a cool cycle…

    What indication is there of that?

    Given we were coming out of a little ice age, I don’t think there’s anything here to be getting alarmed about.

    What forcing, precisely, is responsible for us ‘coming out of a little ice age’? Please support this assertion with data.

    Further, it is only this 0.6C rise that we can attribute anything not natural to, such as greenhouse gasses or other forcings, and that is assuming that this 180yr trend isn’t just part of a longer cycle, possibly headed down again given our weak sun.
    Dr Lindzen was right. Our descendants are going to have a good old laugh at our version of arguing over angels on pins.

    The trouble is, there is around another 0.4 to 0.5C of warming in the pipeline due to the lag in ocean warming, just from ~390ppm of CO2, which takes us to 1.2C above pre-industrial. Then we have to consider how much higher atmospheric CO2 is going to rise – no-one seriously thinks that it’s going to stop rising anytime soon, so there will definitely be more warming on top of that 1.2C. Then also, we risk more warming still from any decline in anthropogenic aerosols (e.g. if industry in China cleans up its pollution). Considering the rapid decline of Arctic ice and glaciers and so on even at current warming, I don’t think our descendents are going to be laughing about our actions. Condemning us, perhaps.

  72. Wow, I’m on a roll.
    I must ask for opinions here. Mine is that the [snip] in the AGW cult have had a small victory of sorts by being able to draw everyone on the Skeptics side into short termism. ie. Last 10 years have been hottest since Marilyn Monroe…etc.
    The claim by the cultists has to be seen in the context of the length of the Industrial Revolution. We should, I think walk away from the short termism and start hammering away at the reality of climate. It cycles. And since the 1840-50s the ‘warming’ has been statistically insignificant within those cycles. The claim of unprecedented warming and a tipping point are like ‘Jesus walked on water and heaven is full of virgins’ . The stuff of fanaticism & Emotional Terrorism.
    The 1850 s are a nice central starting point as the American East was full of industry, Europe as well, so that awful CO2 was being produced in an ‘unprecedented’ amount.
    waddayarekon??? Long term or short term ??
    regards from a cold, wet Southern Oz.

  73. RC Saumarez says:
    July 31, 2010 at 2:40 pm
    @Paul Birch.
    “What are you saying? If sucessive peaks are identical but the shape of a curve deviates from being a pure sinusoid, so that the integral of the sucessive curves wrt time is increased, this has no meaning – “the trend is zero”? ”
    RW said:“1. For a cyclical and regular time series, even measuring trends peak-to-peak or trough-to-trough is not meaningful. See here
    For any “cyclical and regular time series”, such as the pure sine curve used in the test case RW linked, the trend over any integer number of periods is mathematically zero. The script gets that wrong, even for very simple cases, so there’s a bug in it.

  74. I think I see part of the problem. It looks as if when the trend is zero it fails to draw the red line at all. You have to add a little bit to the end time. Btw, by “cyclical and regular” I understand symmetrical about the peaks or troughs. The trend is not necessarily zero for an asymmetrical periodic function, nor between points other than extrema on a symmetric function.

  75. I tried to recreate your graph on the top on the page. Initially I thought there was someting wrong with R. No matter how I tried R kept turning up a horizontal line. After 1,5 hours I gave up and imported the data to Excel and surprisingly I got the same result. The “trend” was absolutely horizontal!
    Only then did I realise that my data was more up to date hence a little longer and since the curve is going downwards those last numbers resulted in a flat trend. It only goes to show how trends can be affected by short series and selection of start and stop values for the trendline. Soon it will go slightly downwards and then we will see the newspaper articles again and in the winter it will go up again.
    I guess we can safely say: there’s not much going on here!

  76. Icarus says:
    July 31, 2010 at 2:18 pm
    …….”I do think Spencer tries hard to minimise the warming in his data series.”
    ==
    Any other opinions, you care to share with us?

  77. nevket240, it’s the contrarians who are always claiming “It’s been cooling for the last 3 years! Global warming is dead!”. Short-termism is their province.

  78. GISTemp is so obviously tampered with it’s easy to find these things.

  79. stevengoddard says:
    July 31, 2010 at 5:14 pm
    Amazingly bad luck for the human race that the satellites came on line in 1979…
    This has given Hansen cover for his cherry-picked trend.
    ______________________________________________________-
    You have that correct Steve. If the satellites had come on line in 1929 we would have seen the sine wave pattern due to the ocean oscillations instead of a linear approximation of one side of the curve.
    Here is what I mean typical graph of an east coast city

  80. Icarus says:
    July 31, 2010 at 4:29 pm
    Only in response to the Goebellists constant media howls of the the ‘hottest 10 years in the last 5’ dah dah adh. 🙂
    1908-1942 (+/_) mmmmmm
    1942-1976 (+/-) mmmmmmmm
    1976-2005 (+/-) mmmmmmmmmmm
    bloody cycles. I wish they wouldn’t keep going around, and around…
    regards

  81. Icarus says:
    July 31, 2010 at 2:45 pm
    paulhan said (July 31, 2010 at 1:35 pm):
    When I look at the long term HADCRUT and superimpose a linear trend on that, it shows a 0.7 rise over the 160 years.
    What does that tell us? Not very much, considering that important forcings over that period, such as TSI and well-mixed greenhouse gases, are not changing linearly.

    It tells us that in 160 years, when CO2 increased by 35%, when we have most of a cooling phase still to come, when we have data collectors trying to wring every last tenth of a degree warming out of the dataset, when the human population went from 1.2 billion to 6.7 billion, when those same humans enjoyed an unparallelled increase in both life expectancy and quality of life, that the best case scenario from a warmist’s point of view, is that temperatures will have gone up by 0.6C in 180yrs, and that that includes any subsequent forcings caused by the increase in CO2. It tells us that you need to get another bogeyman, because CO2 isn’t it.

    However that is with 3 peaks and 2 troughs of a lumpy sine wave, which correlates very closely with the PDO cycles, and could be said to be entirely attributable to natural variation.
    The great increase in atmospheric CO2 over that period is not a natural variation.

    And surely that tells you that CO2 cannot cause the catastrophic climate change that you and people like you keep telling us is going to pass.

    There is every indication that we are past the beginning of a cool cycle…
    What indication is there of that?

    There is the indication that temperatures haven’t risen in a statistically significant way in 15yrs, and that’s straight from Phil Jones. Will that do?

    Given we were coming out of a little ice age, I don’t think there’s anything here to be getting alarmed about.
    What forcing, precisely, is responsible for us ‘coming out of a little ice age’? Please support this assertion with data.

    You tell me!!

    Further, it is only this 0.6C rise that we can attribute anything not natural to, such as greenhouse gasses or other forcings, and that is assuming that this 180yr trend isn’t just part of a longer cycle, possibly headed down again given our weak sun.
    Dr Lindzen was right. Our descendants are going to have a good old laugh at our version of arguing over angels on pins.
    The trouble is, there is around another 0.4 to 0.5C of warming in the pipeline due to the lag in ocean warming, just from ~390ppm of CO2, which takes us to 1.2C above pre-industrial. Then we have to consider how much higher atmospheric CO2 is going to rise – no-one seriously thinks that it’s going to stop rising anytime soon, so there will definitely be more warming on top of that 1.2C. Then also, we risk more warming still from any decline in anthropogenic aerosols (e.g. if industry in China cleans up its pollution). Considering the rapid decline of Arctic ice and glaciers and so on even at current warming, I don’t think our descendents are going to be laughing about our actions. Condemning us, perhaps.

    Ocean temps haven’t gone any higher than 1998 either, so that’s just speculation on your part. To be fair, my predictions are also speculation. But if the past 160yrs is anything to go by, then I think my predictions have a better chance of coming to pass. And we certainly shouldn’t be taking any drastic actions until at least this cool phase plays out.

  82. Global warming rate in the 30-years period from 1970 to 2000, after 60 years of human emission of CO2, was nearly identical to that for the 30-years period from 1910 to 1940 as shown in the following graph for the CRU data:
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1940/compress:12/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1970/to:2000/compress:12/plot/hadcrut3vgl/from:1970/to:2000/trend
    Global warming rate from 1910 to 1940 => 0.15 deg C per decade
    Global warming rate from 1970 to 2000 => 0.16 deg C per decade
    And what is the current global warming rate?
    A slight warming of 0.03 deg C per decade as shown here:
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1990/to:2000/plot/hadcrut3vgl/from:1990/to:2000/trend/plot/hadcrut3vgl/from:2000/to:2010/plot/hadcrut3vgl/from:2000/to:2010/trend
    Note the deceleration of the global warming rate compared to that for the period from 1990 to 2000. Actually, the deceleration is by a factor of 8.3 (=0.25/0.03)
    CONCLUSIONS
    The effect of human emission of CO2 on global mean temperature is NIL, ZIP.
    The recent global warming rate is NOT unprecedented.

  83. Icarus says:
    …The great increase in atmospheric CO2 over that period is not a natural variation…
    …What forcing, precisely, is responsible for us ‘coming out of a little ice age’? Please support this assertion with data…

    What amount of the current warming trend comes from natural variation, and what are the components of that variation? What amount of the current warming trend comes from CO2?

  84. RE: Dave F: (July 31, 2010 at 7:58 pm) “What amount of the current warming trend comes from natural variation, and what are the components of that variation? What amount of the current warming trend comes from CO2?”
    I believe the basic problem here is the fact that our climate appears to be controlled by a poorly understood random convective thermal control system. Perhaps blaming the CO2 greenhouse effect for our modern temperature increase in like blaming the heat from your TV set for making your house warmer while the kids are playing with the thermostat.

  85. Icarus says:
    …Then also, we risk more warming still from any decline in anthropogenic aerosols (e.g. if industry in China cleans up its pollution). Considering the rapid decline of Arctic ice and glaciers and so on even at current warming, I don’t think our descendents are going to be laughing about our actions. Condemning us, perhaps…
    Chinese kids with cleaner air? Not exactly comical, but hardly condemnable.

  86. I says:
    “Chinese kids with cleaner air? Not exactly comical, but hardly condemnable.”
    I meant – ‘breathing’ cleaner air.

  87. Icarus says:
    July 31, 2010 at 2:45 pm
    ……
    The trouble is, there is around another 0.4 to 0.5C of warming in the pipeline due to the lag in ocean warming, just from ~390ppm of CO2, which takes us to 1.2C above pre-industrial.

    But is there more in the pipeline? It’s looking increasingly likely that most of the heating from CO2 forcing to date has been realised. This is this “missing heat” that Trenberth was looking for. It’s simply not there.

  88. Stu: Point is, anthropogenic aerosols offset some of the anthropogenic warming from long-lived greenhouse gases. Clean up the air (good thing) and you inadvertantly remove that warming mitigation (bad thing).

  89. Spector: Are you arguing that the anthropogenic enhanced greenhouse effect is dwarfed by some other, natural forcing? If so, what, and by how much?

  90. Dave F: According to the IPCC here and here, natural forcing is currently around zero, and most of the current forcing comes from long-lived greenhouse gases, partially offset by aerosols.

  91. John Finn: There is currently a net energy imbalance of ~0.5W/m². That’s where the warming ‘in the pipeline’ comes from. It will take at least a couple of decades for that to equilibrate (and by then atmospheric CO2 is likely to be considerably higher, of course).

  92. Girma: Warming in the early 20th Century was largely due to increase in TSI, which has declined in more recent decades. Current warming is about 0.18C per decade due to anthropogenic greenhouse gases. As I’ve pointed out before, 10 years is just showing you natural variability, not the long-term warming trend. Feel free to dispute this if you can.

  93. Icarus,
    Thank you for your numerous comments adding to the traffic total of WUWT. Your support is appreciated.
    However, when you say “According to the IPCC…” you forfeit your credibility. The IPCC has never been accurate, and in fact they are simply tax-sucking charlatans from Rajendra Pachauri on down; the truth is not in them.
    That is what happens when a group of corrupt pseudo-scientists like Michael Mann of the IPCC are paid really large sums of taxpayer loot to reach a pre-determined opinion: there are the financial winners [Mann’s climate peer review clique] and the losers [the taxpaying public]. Honest science and the scientific method are totally ignored in the IPCC’s conspiracy to loot the public treasury.

  94. stevengoddard: So you agree with Hansen that the evidence shows a warming trend of 0.15 – 0.2C per decade since the late 1970s? If so, what are you arguing is the cause of that warming trend?

  95. Paul Birch – actually I’m almost certain the woodfortrees code doesn’t have a bug, at least not in its linear fitting routine. Mathematically, the average of a sine curve over one cycle is zero, but if you sum up the squares of the residuals from the lines you see on the woodfortrees plot, and from the origin, you’ll see that the lines with gradients are “better” fits. This just shows that linear least squares regression isn’t a good way to understand what a sine curve is doing. Using gnuplot I found that for one cycle of a sine curve represented by y=sin(x*pi/32), the “best” fit had the equation y=-0.0283321x + 0.936467. The RMS residual for this fit was 0.444361; the RMS residual from the origin was 0.707107, the square root of 0.5.

  96. Icarus says:
    August 1, 2010 at 2:10 am
    Stu: Point is, anthropogenic aerosols offset some of the anthropogenic warming from long-lived greenhouse gases. Clean up the air (good thing) and you inadvertantly remove that warming mitigation (bad thing).
    This seems to be the case. But maybe a larger case is that there will always be good things and bad things happening simultaneously and that the definitions of these things will alter depending on your focus, culture, or the times.
    Eg. When industrial aerosols were deemed the number one environmental ‘bad thing’ (OMG, Kimberly from Different Strokes has green hair!!!), I wonder how many people were arguing their cooling benefits? A similar case today perhaps in regards to the proposed future warming, where none of the potential benefits of that warming are ever contemplated or discussed. Instead we have semi-serious proposals to inject even more aerosols into the atmosphere to counteract the bad warming. But… didn’t that kind of behaviour itself used to be a ‘bad’ thing?
    Perhaps that Different Strokes episode really got to me and therefore I still feel it’s wrong to spray the atmosphere with aerosols. But perhaps what I really wonder about is the future and how CO2 will come to be regarded outside of the current cultural definition.
    http://www.crackle.com/c/Diffrent_Strokes_Minisode/Green_Hair_Minisode_/2479139
    (just thinking aloud)

  97. Icarus says:
    August 1, 2010 at 2:20 am
    John Finn: There is currently a net energy imbalance of ~0.5W/m². That’s where the warming ‘in the pipeline’ comes from. It will take at least a couple of decades for that to equilibrate (and by then atmospheric CO2 is likely to be considerably higher, of course).

    I’m not sure there is any evidence of this imbalance. This is the problem Kevin Trenberth was confronted with. They either can’t find the missing energy or can’t find “the pipeline”. Can you shed any light on its whereabouts?

  98. Icarus says:
    August 1, 2010 at 3:01 am
    Girma: Warming in the early 20th Century was largely due to increase in TSI,…

    That was the original claim but, according to Leif Svalgaard (and a growing body of opinion), solar variability was much less than previously thought. You may have to look elsewhere for the “unprecedented” rise since ~1902. Of course you could admit -you don’t know but that would imply you didn’t know what caused the post-1970 warming either. Hmmm – tricky one!
    Where would that leave the IPCC’s “Detection and Attribution” studies?

  99. When I look at the 600,000 year graph of temperatures, two things stand out:
    1. We are presently near the top of a warming trend, and the next major move is likely to be sharply downward;
    2. We have had a relatively constant climate for the past 10,000, something that seems to be unprecedented in the last 600,000. What has caused this relative stability?
    I wish that something as simple as adding CO2 to the atmosphere could stave off the next ice age, but I just don’t think that is the case.

  100. What one believes in and where one ‘stands’ on the issues has so much to do with where one has been and what one has come to think about all the ‘stuff’ one has experienced. What is wrong with the Scientific Ethic? Is there such a thing? Is it really more appropriate to ask: what is wrong with the Social Ethic of the West? Is there such a thing? Where have we in the West been and what have we come to ‘think’ about all the ‘stuff’ we have experienced? What do we believe? Where do we ‘stand’? It is facinating to study and analyize other people –it gives so many of us something to thinks about and take our minds off ourselves.
    Did Herr Mann have a lifetime of rather odd, air conditioned experiences and come to think and believe that the World was getting warmer? Did his high school math teachers let him slide on graphing? Did he ever learn the Social Ethic of the West, if there is one? Did he ever learn the Science Ethic, if there is one? Does it really matter what primary school teachers and college professors believe in? Why?

  101. ” Icarus says:
    July 31, 2010 at 2:18 pm
    ‘Alexej Buergin said (July 31, 2010 at 11:46 am):
    What does not make sense is the fact that Hansen observes the trend of 0.2°C per decade (for 1998 to 2009), whereas Jones or Spencer do not.’
    Spencer’s MSU UAH shows 0.14C per decade over the full data set.
    RSS is 0.16C per decade.
    GISTEMP is 0.17C per decade.
    HADCRUT3 is 0.16C per decade.”
    O! say can you see that I have written something in brackets? It says there 1998 to 2010. Your “rebuttal” is about the full data set. So you are trying to fly too high.
    As Phil Jones said: There was no significant warming during the last 15 years.

  102. RW says:
    August 1, 2010 at 3:15 am
    Paul Birch – actually I’m almost certain the woodfortrees code doesn’t have a bug, at least not in its linear fitting routine. Mathematically, the average of a sine curve over one cycle is zero, but if you sum up the squares of the residuals from the lines you see on the woodfortrees plot, and from the origin, you’ll see that the lines with gradients are “better” fits. This just shows that linear least squares regression isn’t a good way to understand what a sine curve is doing.
    _________________________________________________________________
    On re-examination, I think you’re probably right. There do seem to be bugs in the plotting routine, and bugs (or, possibly, confusing “features”) in the way the form deals with the from and to parameters.
    On the substance of what you say, I agree with you. I would go further and say that, for weather data, which is notoriously long-tailed, the least squares method (designed for gaussian errors) is inappropriate. It would be better to use a least error method (minimising the sum of the magnitude of the errors – remember to take the modulus before summing) . This ameliorates the danger of outliers erroneously dominating the results. Also, if you have reason to believe that the curve you are fitting is roughly periodic, it’s better to fit to a sine wave modulating a linear trend, so distinguishing the two effects. Although one can fit linear trend lines to cyclical phenomenon, the results aren’t a whole lot of use – except as propaganda!

  103. Icarus @ August 1, 2010 at 2:17 am says:
    Dave F: According to the IPCC here and here, natural forcing is currently around zero, and most of the current forcing comes from long-lived greenhouse gases, partially offset by aerosols.
    There is one natural forcing, solar, in that graph. Is the only known climate forcing made by nature the Sun? I would like to see someone use that graph to explain the sudden drop into ice ages, or the temperatures during the carboniferous.

  104. Kim, I am not a scientist. I am hardly a maven, but thanks for the complement.
    Steve Goddard, when I tried peak to peak, I was warned to not use extreme events (peaks or troughs), but instead use averages. The peaks and troughs are associated with short term anomalies like El Nino, La Nina, and volcanoes. It is best to not use them.
    John M Reynolds

  105. Larry said (August 1, 2010 at 6:16 am):

    I wish that something as simple as adding CO2 to the atmosphere could stave off the next ice age, but I just don’t think that is the case.

    Why not? The palaeoclimate data suggests that millions of years ago the Earth was permanently ice-free with the sun being cooler than it is now, the difference being due to the higher atmospheric CO2 that prevailed then. If we achieve the same situation in the future that nature did in the past, wouldn’t it be reasonable to expect the same consequences? If not, why not?

  106. RE:Alexej Buergin: (August 1, 2010 at 7:56 am) “O! say can you see that I have written something in brackets?”
    I believe this system treats anything inside angle-brackets to be HTML tag coding, such as I used above to italicize the quoted text. Invalid or disallowed tags are ignored.

  107. RE: Icarus: (August 1, 2010 at 2:13 am) “Spector: Are you arguing that the anthropogenic enhanced greenhouse effect is dwarfed by some other, natural forcing? If so, what, and by how much?
    It is well known that there is a maximum stable adiabatic lapse rate linking surface temperatures to the temperature of the tropopause. Every time we have a convection event, nature’s natural air-conditioner has just kicked in. Depending on the situation, this can be violent or gentle.
    So far, I have not seen anyone attempt to explain what happened to this natural temperature regulation system in the transition from the Medieval Warm Period to the Little Ice Age. Perhaps something forced the tropopause to a lower altitude and this drove colder temperatures to the surface or perhaps something caused a general cooling of the tropopause level and this was reflected to the surface via the required stable lapse rate.
    It appears to me that much of the discussion so far has been focused on surface heating effects with little regard for the fact that surface cannot warm unless the tropopause warms likewise or the rises to a higher level. As the concentration of gaseous water (water ‘vapor’) in the atmosphere is about 100 times that of CO2, I would think that the behavior this gas would be the most important in determining the tropopause level. I have not found any historical year-by-year tropopause temperature and altitude data provided anywhere online.
    Another important point is the fact, pointed out by Dr. Spencer, that the tropopause is the level where Earthshine absorbing and emitting (greenhouse) gases primarily serve to cool rather than heat the atmosphere.

  108. @Icarus – you said
    “palaeoclimate data suggests”
    ….. suggests ?
    My bank manager “suggests” that I reduce my overdraft,
    but in this economic climate, it ain’t gonna happen !!!!
    what namby-pamby wishy-washy mindless moronicism is this ?
    now a suggestion is all you need as “proof” and then spend
    how many billions on the stength of such suggestions ????
    Total Humbug !

  109. It doesn’t really matter whether the trend is “anthropogenic” or not–it matters what will happen to the Environment, right?
    So why are all the posts about physics and clouds and not about polar bears “declining” in numbers from 5000 a few decades ago to 15 000 now, and other biological science.
    Where are all the reports on what carbon dioxide does to grasses (growth up 65% with 10x CO(2) under ideal conditions) or trees (double under similar conditions).
    How come we go to the “Tropical Rainforest” section of the Botanical Gardens for the most species Diversity, not to the Arctic Tundra section (which did not even exist)?
    If any of this were really about science, we would see thousands of articles on plants, not hundreds, and tens of thousand of articles on terrestrial vertebrates. I found two articles so far in my search for “carbon dioxide levels growth” in the near-ambient range–both of which showed faster growth and earlier hatching in chicken eggs with elevated CO(2).
    I found lots of articles with pure speculations about how “global warming” might harm some species, not actual studies of distributions.
    Solving this suppression of science is not going to happen by begging the mainstream media by a handful of real scientists (they can’t tell the difference, anyway), nor by getting one good science minister somewhere, and certainly not funding by the oil companies–they pay the greens millions of dollars, giving the greenies strength to dog all their supplies efforts–which RAISES their profits by the Law of Supply and Demand.
    But the mid-level coal and oil guys–the gas station owners, the geologists, the miners–those guys know the facts. We need to hook up with them to get the truth out to the general public and the politicians.

  110. Richard M said (August 1, 2010 at 8:55 am):

    Icarus, please show exactly where that pipeline enrgy is hiding. Be specific.

    It’s in the current global energy imbalance (i.e. radiative energy received from the sun exceeds that radiated back to space from the Earth). That will take some decades to equilibrate, even if CO2 doesn’t rise any more (which is extremely unlikely).

  111. Icarus says:
    August 1, 2010 at 2:57 pm

    Richard M said (August 1, 2010 at 8:55 am):
    Icarus, please show exactly where that pipeline enrgy is hiding. Be specific.


    It’s in the current global energy imbalance (i.e. radiative energy received from the sun exceeds that radiated back to space from the Earth). That will take some decades to equilibrate, even if CO2 doesn’t rise any more (which is extremely unlikely).
    Ok – thanks for that, Icarus , but I think most of us are aware that the claimed imbalance is due to an imbalance between incoming solar radiation and outgoing LW radiation from the “top of the atmosphere”. The point is that this extra energy must be accumulating somewhere. The problem is that no-one seems to know where. This is a comment by Kevin Trenberth:

    > The fact is that we can’t account for the lack of warming at the moment
    > and it is a travesty that we can’t. The CERES data published in the
    > August BAMS 09 supplement on 2008 shows there should be even more
    > warming: but the data are surely wrong. Our observing system is inadequate.
    I think Richard M might have been asking you to be more specific about where the “hidden heat” might be hiding.
    PS If you do happen to come across it please let Kevin Trenberth know.

  112. Talk about cherry-picking! Look at his start point. He chose the worst case trough to crest to measure his trend.

    There is no oscillation in the temperature record in 30-year periods. There is no even remotely recognizable ‘peak and trough’ in the instrumental record on decadal scales. One could argue there is an oscillation in the data (PDO), but it does not account for the long-term trend. There is year by year oscillation in the temp record – global temps tend to be warmer during Northern Hemispheric summer – but Hansen took annual averages, and did not, nor could not, make the same mistake Goddard did on sea ice data.
    Hansen’s 30-year trend (of temperature) is far more statistically significant than a 9 year trend (of Arctic sea ice). How soon we forget that statistical significance tests fail for global temperature starting if we start from 1995 to 2009 – 15 years (if you’re reading this post in 2011, that may no longer be the case). That factoid was made much of at Watts Up With That, but it seems to stop no one here from prognosticating on climate trends with much shorter time periods. This lack of consistency hardly inspires confidence.
    (Aside: sea ice trends probably don’t need as many years as climate trends to achieve statistical significance, but 9 years is statistically insignificant for either metric)
    While we’re on the subject of cherry-picking, I ran the regression function on sea ice data at wood for trees, matching the (erroneous) method used by Steve Goddard, who runs the plot from mid-2002 to present. From mid-2001 to present, there was a shallower upwards trend. From mid-2000 to present, a flat trend. Every year back thereafter (starting at 2000, then 1999, 1998 etc), the trend to present was of reduced sea ice. Selecting 2002 as a start point is cherry-picking – or in the words much expressed at WUWT re Jones and temp trends since 1995, it’s not ‘significant’.
    There are sound reasons to compute global temps for the last 30 years – can cross-check with satellite record and with sea ice record, solar output has been flat or slightly waning in that period, the flat or cooling mid-century temps may have been a product of aerosols from industry (cleaned up since then by regulations on emissions), and the time period is statistically robust. Readers could be led to believe, however, that Jim Hansen doesn’t talk about pre-70s global temperature. That’s just wrong.
    (I could be wrong, but I think the first link in the article goes to the wrong WUWT page. Shouldn’t it be: http://wattsupwiththat.com/2010/07/02/arctic-ice-increasing-by-50000-km2-per-year)

  113. ” Spector says:
    August 1, 2010 at 9:51 am
    RE:Alexej Buergin: (August 1, 2010 at 7:56 am) “O! say can you see that I have written something in brackets?”
    I believe this system treats anything inside angle-brackets to be HTML tag coding, such as I used above to italicize the quoted text. Invalid or disallowed tags are ignored.”
    It seems that in England ( ) and [ ] are called brackets, in the US only [ ]. It used ( ) and they stayed there.

  114. The title of Goddard’s contribution is “crest to crest”. Most people agree that this is the best (or least bad) way to calculate a trend. February (maybe April) of the El Niño-year 1998 is the first peak, and March (maybe July) of the El Niño-2010 is the second one (UAH). So copy the monthly UAH-data into an Excel file, let it calculate the trend, then you get an indication of the warming during the last decade (or 12 years), and nobody can accuse you of cherry-picking.
    Phil Jones must have used CRUtemp, of course, when he says there was no significant warning during the last 15 years.

  115. Alexej Buergin says:
    August 2, 2010 at 1:59 am
    “It seems that in England ( ) and [ ] are called brackets, in the US only [ ]. It used ( ) and they stayed there.”
    In English English ( ) are properly called parentheses, [ ] are properly brackets, { } are properly braces, and are improper!
    However, in common or lazy English English ( ) are often called brackets or round brackets, [ ] are often called square brackets, <> are called angle brackets, and { } are called … er … those wiggly thingies!

  116. Just to correct/clarify the use of “last” on WFT here. “last:N” takes the last N samples from the current date – so for example, last:120 gives the last ten years data measured from the time the viewer fetches the graph (not the time you first made it!). The combination of “from” and “last” doesn’t make sense, and actually only works because 2010 is a huge number of samples so doesn’t limit the interval already set.
    I think Steven meant to use “to:2010” in the initial graphs, which would fix the end-point even if the graph was re-viewed in 2011, 2020 or whatever. Remember that WFT uses decimal years and does not include the ‘to’ end-point: technically left-closed, right-open = [from,to). So “to:2010” gives December 2009 as the last sample. That means if you do from:2000/to:2010 you get the expected 120 samples.
    Icarus/Paul Birch: The OLS C++ code is available on the site – if you think there is a real problem there please contact me privately.
    Cheers
    Paul

  117. Apologies, it was “RW”, not “Icarus” who was discussing the OLS accuracy. I find it hard to remember names even usually, initials and pseudonyms doubly so!
    After re-reading the comments above, I’m a bit confused what (if any) issues in WFT are being reported – can you clarify?

  118. ” Icarus says:
    August 1, 2010 at 9:25 am
    Alexej Buergin: Why do you prefer the 1998 – 2010 data rather than the whole data set?”
    This is what I tried to answer at 2:15 a.m.

  119. Alexej Buergin:
    Is 12 years sufficient to determine a trend? Wouldn’t 30 years be better? Why or why not? What particular reason might you have for choosing 1998 – 2010 to determine a trend rather than 1980 – 2010?

  120. Icarus says: [ … ]
    Your questions have been answered in detail numerous times here. I suggest you read the WUWT archives for a few weeks to get up to speed on the subject.

  121. woodfortrees (Paul Clark) says:
    August 2, 2010 at 5:22 am
    “After re-reading the comments above, I’m a bit confused what (if any) issues in WFT are being reported – can you clarify?”
    OK. Look at http://www.woodfortrees.org/plot/sine:10/from:1902.5/to:1912.501/trend/plot/sine:10/from:1902.5/to:1912.5/trend/plot/sine:10/to:1950
    1902.5-1912.5 the trend should be zero, but comes out significantly negative (green line). Adding a teeny bit to the end time shouldn’t make much difference but obviously does (red line). It would appear that entering 12.5 causes the last sample at 12.5 to be lost. At best, this is confusing.
    It also appears that the (series 1) red line vanishes if one of the later series overlays it. This is also confusing when one is playing around with the first series (well, it confused me!). It might be better to have the plotting priority the other way round (earlier series have preference).
    There was also another case where the trend line did not appear, but the scale of the graph suddenly changed (presumably because the trend line would have stuck over the top), but unfortunately I’ve forgotten what parameters I used and can’t replicate it (mea culpa).

  122. Phil Jones must have used CRUtemp, of course, when he says there was no significant warning during the last 15 years.

    That’s not what he said, that is what the press and skeptical blogsites erroneously reported he said.
    He said that the warming between 1995 and 2009 was not statistically significant. A lot of people didn’t understand what that qualifier meant – basically that the confidence level of the trend was slightly less than 95%. It’s a warming trend, but there is a non-negligible chance that the trend could be zero.
    By the end of the year, the temperatures since 1995 will have statistical significance. Then some eejit will say, “there has been no significant warming since 1996,” again confusing a statistical term with its common usage.

  123. Hi Paul,
    Thanks for this. I think the problem comes – as you’ve realised – from the half-open interval, and whether the final sample is included or not. Entering exactly 1912.5 means that 1912.42=0.499 (June 1912) is the last sample, which is lower than 1902.5=0.5 – hence the slight negative trend. 1912.501 includes 1912.5 (July 1912) and the trend is then zero, as you’d expect.
    I think you may be trying to make what is a system designed for discrete monthly data fit a pure mathematical ideal with infinite precision. OK, you could argue for a closed interval (so 1912.5 would be included) but for every benefit that brings, another gotcha springs up – for example, that from:2000/to:2010 would have 121 samples.
    It’s also inevitable that lines plotted on top of each other will cover each other up. Last on top seems like the most logical given I had to choose…
    I’m happy that you don’t think the OLS algorithm itself isn’t bad, as originally claimed!
    Cheers
    Paul

  124. woodfortrees (Paul Clark) :
    I hadn’t realised that the datapoints were monthly (though now you mention it, that makes sense). This makes the decimal data entry rather messy. I wonder if it might be better to use months there, ie., 1900.0 (December 1899) to 1900.11 (November 1900). Then I would suggest using the end dates inclusively, but weighting the end samples so that there are still 12 samples a year. Thus 1900.0 – 1910.0 would give only half weight to the 1900.0 and 1910.0 samples, full weight to the rest. Whereas 1900.05 – 1910.05 (in base 12 method) would give zero weight to 1900.0 and 1910.1, but full weight to 1900.1 and 1910.0 (and everything between).
    Whatever you decide, I think you need to show clearly, somewhere on the working page, what conventions you’re using – and warn users about any traps they’re likely to fall into. You may already do that somewhere on site, but I couldn’t find it.

  125. ” Icarus says:
    August 2, 2010 at 5:31 am
    Is 12 years sufficient to determine a trend? Wouldn’t 30 years be better? Why or why not? What particular reason might you have for choosing 1998 – 2010 to determine a trend rather than 1980 – 2010?”
    12 years is long enough to calculate the trend for these 12 years if beginning and end are comparable. 30 years is not long enough to say something significant about climate.
    If you have a sine with a period of 12 years, 12 years from crest to crest would be OK.
    30 years could go from trough to crest or from crest to trough, and that is not OK.

  126. ” barry says:
    August 2, 2010 at 8:25 am
    He said that the warming between 1995 and 2009 was not statistically significant. A lot of people didn’t understand what that qualifier meant – basically that the confidence level of the trend was slightly less than 95%. It’s a warming trend, but there is a non-negligible chance that the trend could be zero.”
    A sociologist, a physicist and a mathematician went to France and saw a black sheep.
    Sociologist: “The sheep in France are black”.
    Physicist: “There is a black sheep in France”.
    Barry the mathematician: “There is at least one sheep in France, which is black on at least one side”.

  127. RE: Paul Birch: (August 2, 2010 at 9:09 am) “I hadn’t realised that the datapoints were monthly (though now you mention it, that makes sense). This makes the decimal data entry rather messy.”
    Just for reference, the simple formula I use in Microsoft Excel to create decimal dates from year and month numbered data is:
    Yeardate = [year] + ([month] – 0.5)/12
    I usually do not try to calculate the exact mid-month date on the assumption that this precision is lost in the noise.

  128. Alexej, I have no ideas what your analogy is supposed to mean, but here is the trend 1995 – 2009 based on HadCRUt.
    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1995/plot/hadcrut3vgl/from:1995/to:2010/trend
    About 0.1C per decade, a stronger warming trend than the 20th century. In common terms, that is ‘significant’.
    In mathematical terms, the time period just fails statistical significance – the confidence level for this plot is slightly less than 95%. That is what Jones was saying. By 2011, the trend from 1995 will achieve statistical significance, and unless there is a huge plummet in temps for the rest of this year, the trend will have increased a bit.
    12 years is way too short to achieve statistical significance with respect to global temperature trends.

  129. ” barry says:
    August 2, 2010 at 12:18 pm
    Alexej, I have no ideas what your analogy is supposed to mean”
    It means that most people here know what “statistically significant” means, so you do not have to recite the whole definition every time. And that mathematicians are complicated people by nature.
    And Goddard’s point is that one should start in 1998 (crest), not in 1995, anyway.

  130. Alexej Buergin:
    We all know that 12 years is not long enough for a trend, for obvious reasons. If you want to do a ‘crest to crest’ trend then it makes much more sense to pick 1983 to 2010 which will give you a trend of 0.18C per decade.
    Agreed?

  131. Icarus says:
    July 31, 2010 at 2:45 pm
    ……
    The trouble is, there is around another 0.4 to 0.5C of warming in the pipeline due to the lag in ocean warming, just from ~390ppm of CO2, which takes us to 1.2C above pre-industrial.
    ……
    The amount of unrealized temperature gain can be modeled as a bank account. We are depositing carbon forcings (delta ln(co2)) and nature is withdrawing from this unrealized account and transferring it to the realized account.
    This model is known in financial terms as the accumulated value of a continuously compounding annuity with continuous payments. The accumulated value factor is: (exp(RT)-1)/R, where R is a rate (negative in this case) and T is time.
    Now because R is negative, as T goes to infinity, the exp(RT) term goes to 0 and the accumulated value converges to -1/R.
    To estimate R, I calculated that there is about an 80 day lag in SST’s from seasonal solar forcings. I’ll skip the math, but this gives R=-1.23 on a yearly basis. This means that there can be no more than .83 years worth of carbon deposits left in the unrealized temperature gain account. In effect, all co2 deposits up to last year have been fully realized and this would leave only one or two hundredths of a degree in the pipeline.
    BTW, I’m not just making this up. The exp(RT) term was used by none other than Sir Issac Newton himself in his “Law of Cooling” and has been confirmed by countless small scale experiments. Does this scale up to the global level? Not sure, but I haven’t seen anything that refutes it. The .4 to .5C that you quote probably comes from the complicated computations hidden in the climate models.
    Also, I have done the same exercise assuming a more realistic linearly increasing deposit rate, and the conclusion is the same. The amount in the pipeline converges to a very small amount. That is probably why Trenberth can’t find it.
    HTH,
    AJ

  132. The trend given by linear regression is strictly valid only if all the residuals are independently distributed random variates. Cyclical components in the time series (e.g., annual cycle) introduce strongly autocorrelated residuals and produce similar oscillatory behavior in the trend of any fixed length computed on a running basis. This plays havoc with intuitive notions of trend. The most effective way of eliminating such cyclical components is NOT to “anomalize” the series by subtracting an annual “norm” estimated from a pitifully short stretch of record (as is the case with JAXA data) but to do a running yearly average. This simply filters out the annual cycle and all of its harmonics without having to estimate them.
    But even then, the indications obtained from short records remain highly tenuous, because of irregular multidecadal and longer oscillations. No record shorter than twice the longest such oscillation can provide a semblance of determining whatever SECULAR trend there may be in the underlying process. In most cases, records of such length are simply unavailable and all references to trend are limited to just that particular stretch of record.

  133. AJ says:
    August 3, 2010 at 10:53 am
    “I’m not just making this up. The exp(RT) term was used by none other than Sir Issac Newton himself in his “Law of Cooling” and has been confirmed by countless small scale experiments. ”
    Nicely done! The whole idea of “heat in the pipline” comes from unrealistically long time constants attributed to the climate system and to the model calculations of TOA “energy imbalance.” Meanwhile, as ERBES revealed, with all sorts of data massaging being necessary to bring measured discrepancies between different satellites within 10W/m^2 of each other, the premise that the present balance is accurately known empirically is a myth.

  134. Alexej,

    It means that most people here know what “statistically significant” means, so you do not have to recite the whole definition every time. And that mathematicians are complicated people by nature.
    And Goddard’s point is that one should start in 1998 (crest), not in 1995, anyway.

    The time period from 1998 to present fails statistical significance. This is not calculated by selecting start/end points on a perceived cycle – that is a complete misunderstanding of the notion, which sky describes fairly well (although the bit on anomalies is irrelevant).
    We also had an el Nino in 2007. According to you, we could measure from that peak to the present peak and get a statistically valid trend. Even a layperson should be able to tell this is nonsense.

  135. It’s worth noting that el Nino periods are not symmetrically cyclical as is the case with annual fluctuations of sea ice cover. El Nino cycles are 5 years on average, but peak to peak can be as short as 2 years and as long as 7 years. Sea ice cover increases and decreases on a monotonous 1-year cycle, winter and summer.
    El Nino periods themselves are not symmetrical in their duration. They also can peak at any month in the year, although they tend to be centred on the beginning/end of the years.
    In order to discern an underlying trend from noisy, near-chaotic data, you need to work with a long enough time period where the noise is canceled out. 12 years is not enough.
    One of these days, a competent statistician may work the sums for us, and deliver the statistical confidence value for the period 1998 – to present (August 2010). There are skeptical contributors to this website with the skill to do that, but for reasons unexplained, they never do (AFAIK).

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