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
“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.
Your link at the top for “I wrote an article showing the trend in Arctic ice since 2002” http://wattsupwiththat.com/2010/07/29/reviewing-last-months-forecasts-of-doom .
That seems wrong, did you mean to link to the top of the July 2nd article http://wattsupwiththat.com/2010/07/02/arctic-ice-increasing-by-50000-km2-per-year/ ?
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???
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.
So what happened with the “ten years of cooling”?
@ur momisugly 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.
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)!
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:
http://www.eastangliaemails.com/emails.php?eid=462&filename=1105019698.txt
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.
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.
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?
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.
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!
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?
Jean Meeus said (July 31, 2010 at 7:33 am):
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.
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.
Ric,
Yes, looks like I put in the wrong link.
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.
James Sexton
The GISS slope is 4X of the UAH slope, and 16X of the RSS slope. It isn’t credible.
John Finn said (July 31, 2010 at 7:39 am):
Hansen’s conclusion is based on 30 years of data. Isn’t that enough?
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.
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.)
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.
Girma said:
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.
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?
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.