Mathematician Luboš Motl takes on the new UAH data (source here) and some current thinking about slopes in global climate by adding his own perspective and analysis. Be sure to visit his blog and leave some comments for him – Anthony
UAH: June 2009: anomaly near zero
UAH MSU has officially released their June 2009 data. This time, they’re faster than RSS MSU. The anomaly was +0.001 °C, meaning that the global temperature was essentially equal to the average June temperature since 1979. June 2009 actually belonged to the cooler half of the Junes since 1979.
Global warming is supposed to exist and to be bad. Sometimes, we hear that global warming causes cooling. In this case, global warming causes global averageness. In all three cases, it is bad news. The three main enemies of environmentalism are warm weather, cool weather, and average weather.
It is not a coincidence that these enemies are very similar to the four main enemies of communism. The four main enemies that were spoiling the success of communism were Spring, Summer, Fall, and Winter. 🙂 See Anthony Watts’ blog for additional discussion.
Bonus: trends over different intervals
You may have been intrigued by my comment that the cooling trend during the last 8.5 years is -1.45 °C. What is the result if you choose the last “N” months and perform the linear regression?
You may see that the cooling trends are dominating for most intervals shorter than 110 months; the trend in the last 50 months is around -6 °C per century. Only when the period gets longer than 150 months i.e. 12.5 years (but less than 31 years), the trend becomes uniformly positive, around 1.2 °C per century for the intervals whose length is close to 30 years.
Note that those 12.5 years – where you still get a vanishing trend – is from January 1997 to June 2009. If you consider the UAH mid troposphere data instead (relevant for the part of the atmosphere where the greenhouse warming should be most pronounced, according to both proper atmospheric science and the IPCC report, page 675), all the trends are shifted downwards:
You need to consider time periods longer than 180 months i.e. 15 years (at least from Summer 1994) – but shorter than 31 years – to see a uniformly positive warming trend. And the trend that you can calculate from those 30+ years is just 0.4 °C per century and chances are that this 30+-year trend will actually drop below zero again, in a few years. At any rate, the blue graph makes it clear that in the right context, the longer-term warming trend converges to zero at a very good accuracy.
According to the IPCC, the surface warming trend should be around 3 °C per century which should translate to a 4-5 °C warming per century in the mid troposphere where the greenhouse effect has the strongest muscles. You see that according to the last 30 years of the data, the IPCC overestimates the warming trend by one order of magnitude!
Because the mid troposphere is the dominant locus of the greenhouse “fingerprint”, this is the most appropriate method to check the validity of the IPCC predictions. Their order-of-magnitude error is equivalent to the mistake of a biologist who confuses squirrels and elephants.
To be more specific about a detail, half of the Earth’s surface is between 30°S and 30°N – because, as Sheldon Cooper said in TBBT, sine of 30 degrees is exactly 1/2. But the mid-troposphere warming (8 km above the surface) is faster than the surface at least between 40°S and 40°N, i.e. on the majority of the surface, so it is likely that even when you take the global averages of both quantities, the mid-troposphere should see a faster warming than the surface.
Someone may argue that those 30 years represent too short an interval and the trend will be higher in 100 years. But such a reasoning is a wishful thinking. Moreover, periods longer than 30 years don’t really belong to the present generation. In 30 years, most of the population of the Earth won’t remember the year 2009 – and they shouldn’t be affected by stupid fads of those mostly dumb people from 2009.
The scientific data and anecdotal stories (“cooler and wetter than previous years”, etc.) reinforce each other. Same pattern in general between the temperate and tropical countries.
Is there a formal meteorological/geological definition for the number of years encompassed by the term, “climate?” Roughly how many years does it take to shift from one set of climate averages to another, and how is that related to the duration of the “stable” climate periods? Whenever the Earth does undergo a climate shift, what are some statistics that could be used during the shift to measure/project the magnitude of the shift. For example, the number of temperature, precipitation, hurricane, etc. records being broken when compared to the previous stable period. It would be nice to have some formal definitions in the area of climate change using statistics and the mathematical theory of chaos.
Dear Anthony,
Lubos is not a mathematician, but physicist, working on string theory.
noaaprogrammer (09:50:13) : Is there a formal meteorological/geological definition for the number of years encompassed by the term, “climate?”
I’ve often wondered this. Why is 30 years defined as climate? Why not 3 or 300 or 3000 or 30000? I keep wondering as a lot seems to ride on the number chosen. To be fair someone did once post a reply as to why, but I didn’t understand the answer.
Add me to those experiencing an unusually cold and wet May-early July here in New England. What I gather from the informative post is that to project a warming trend, one must carefully select the particular time period to compute the moving average. I doubt that such cherry picking data selection methodology exhibits statistical significance. Another great guest science post in a fine science blog.
Given that CO2 levels are higher this decade than the decades of the last half of the 20th Century, should we not be seeing readily measurably higher temperatures according to IPCC dogma?
IceAgeNow has a story on where they’re predicting possible frosts for Canada’s Avalon peninsula around Newfoundland
http://www.weatheroffice.gc.ca/warnings/report_e.html?nl11
If we lived up there we’d have to take our ferns inside and cover the flowers during a time which is supposed to be the hottest part of the year. Speaking of flowers I noticed a few foolish Sunflowers here blooming more than a month early when it’s supposed to get to 100 degrees in a few days O.o.
I’m almost surprised temperatures aren’t shooting upward in response to SST’s by now, perhaps the PDO, AMO, Serychev, and the sun are all acting as a drag
The 0.4C rise is the same as that suggested by Dr Roy Spencer & “The Diatribe Guy” in their blogs.
Three identical results from 3 different methods, better than the IPCC models can do.
philw1776 (10:09:51) :
“Given that CO2 levels are higher this decade than the decades of the last half of the 20th Century, should we not be seeing readily measurably higher temperatures according to IPCC dogma?”
I’ll bet they are measurably higher. Average global temps for a decade around 1995 and 2005 and see what you get. Then try it for a few more decades back.
I am surprised temperatures are not much cooler than they are, given that the sun has been remarkably quiet of late. Surely one would have thought that temperatures should be much lower than the 1979 average by now?
Who cares what your facts say, the Gorical has spoken and the debate is over. Who can deny the Gorical!!!
Not to belabor the point, but a squirrel to an elephant is about three orders of magnitude. A horse to an elephant would be about right.
A meteorologist on Accuweather is saying the quiet sun could be contributing to the relative coolness of the Northeast, when taken in the light there have been no Tambora-sized eruptions as of recent
http://www.accuweather.com/regional-news-story.asp?region=eastusnews
I wonder if it’s true for the Northwest as well, they’ve gotton some relatively cool days, also it seems Summer has been awol for a number of days in the Canadian city of Edmonton which Intellicast is forecasting low 60 and below for several days for them.
# Stefan.
Cited from H.H. Lamb, ‘Climate, history and the modern world’, 1995, page 11:
” … A step in the direction of standardization was taken at the 1935 conference of the International Meteorological Organization (forerunner of the present World Meteorological Organization) when use of the observations of the years 1901-1930 for all climatic purposes was recommended as the so-called ‘climatic normal period’. Choice of the world ‘normal’ turned out to be unfortunate, but it has persisten in climatological practice. It spreads the impression that nature recognizes such a norm and the conditions should continually return to the regime of the chosen period. Wenow know that 1901-1931 was a highly abnormal period, though it was surpassed by the following thirty years 1931-1960, which were in due course substituted as the ‘new normal period’. Globally these were probably the warmest, and in many regions the moistest, regions periods of such length for centuries past. …”
See more here.
http://books.google.nl/books?id=0Nucx3udvnoC&dq=climate+definition+thirty+years&source=gbs_navlinks_s
With a special thanks to William Kininmonth – former head of Australia’s National Climate Centre, who explained this to me earlier this year.
“Global warming is supposed to exist and to be bad. Sometimes, we hear that global warming causes cooling. In this case, global warming causes global averageness. In all three cases, it is bad news. The three main enemies of environmentalism are warm weather, cool weather, and average weather.”
Weather is bad for you. Weather is part of the environment. The environment is bad for you. Weather is part of the Climate. The Climate is bad for you.
I could think of two reasons to say that “climate” is a 30 year period. One would be that with a sample of 30 years of data you could say the sample was “large” in statistical terms, but really this isn’t a physically motivated rationale. The other reason could be the existence of underlying physical cycles that had length of 15 years.
# Stefan, Noaaprogrammer
There are several scientists active in climate research that argue that there is no unique period that can be used to define “climate”. Reason is that the notion that climate appears to be non-stationary, i.e. that after subtracting a mean the remaining variability still contain non-random variations (for example long term persistence), and these remaining variations THUS are not random.
It appears that such variations occur on all sorts of timescales, although there are some preferences within the climate system for certain periods, like ENSO, typically about 3-5 years, or PDO, 30-60 years or Oeschger-Dansgaard variations (1470 years) or the ice ages.
Nevertheless, the question is valid, and you can defend that there is no unique climate-timescale. I guess it all depends on the timescales and response times of various sub-processes that play a role in climate.
Still, for practical purposes – like a weather forecast – it is nice to be able to say that ‘for the time of the year it is warmer or colder than usual’ as we are so used to for example the ever changing seasons.
Summer isn’t AWOL in the Phoenix, AZ area. We’ve been a bit below normal lately in the mid 100’s, but the forecast for Saturday is 116. That’s somewhere between the normal and the record for that day. This is the time of year where we expect more 115-118F days. Where are these frost warnings again? Is there gainful employment available? 🙂
dennis ward (11:00:12) :
Time spent in minimum conditions plus latency plus prevailing patterns (noise) determines who get what when and how much. Ask not for whom the cold comes, it comes for you. Your only advantage in this is that, unlike previous civilizations, you have records of what has been. And that’s about all the warning you are ever likely to get, seeing that the present crystal ball of AGW is no better at predicting the future than those who read tea leaves or entrails, or those who forecast endless prosperity in the CDO swap market.
It all seems so simple until the bottom falls out.
Choose your poison. Long or short, boiling or freezing. If you guess at it, your chances are 50-50. If you happen to be observant and pick out the right indicators, you may do better. If you take somebody else’s word for it, you are still guessing.
noaaprogrammer (09:50:13) : Is there a formal meteorological/geological definition for the number of years encompassed by the term, “climate?
I think 30 years is the minimum used by researchers in the field. I also thought the years 1951-1980 were the baseline used in the RSS and UAH temperature graphs provided by this site? Can someone confirm or correct this assumption?
For example the 1st point plotted, Jan 1979 is ~ -.15 C (on the UAH chart). I thought that indicated it was .15 C below the 1951 – 1980 average global temperature? If not what is it indicating?
#Gary Crough
According to the UAH website:
http://vortex.nsstc.uah.edu/data/msu/t2lt/readme.06Jul2009
“Note that the base period for the mean annual cycle for
t2lt is now 1979-1998, or 20 years instead of the previous
1982-1991 ten years.”
So it is the anomaly compared to the 20-year mean for 1979-1998.
I am pretty sure those graphs representing the trend over various periods looks a lot like the graph of trends in a random data set;
It flails about wildly on a small sample set, switching signs less and less frequently as sample size increases, then somewhere between 50 and 200 events, it picks a sign and diminishes to zero over about a thousand events such that x=n and y = RND(+1 or -1).
Try it out in excel if you want, it’s a simple statistical experiment. I am reasonably confident there’s some interpretation to be made, depending on the number of y intercepts and the sample size, but I haven’t looked much deeper than that.
Sorry if that is too pedestrian for the fully engaged scientific mind, but I found it useful.
Hmmm. . . . Statistics 201 to the rescue!
Maybe the 30 year period chosen for climate is based on the underlying political-cultural cycle. Which would be based on the average term of ambitious young charlatans who could rise by peddling nonsense because their elders and betters were retiring. Roughly 30 years?
What’s truely remarkable about that is when you introduce a trend of 1 per 100 (i.e. 1 ‘degree’ per century or .01 per ‘n’) there’s two intercepts at less than 10 events, and after about 35 events, there is no doubt that it’s not trending toward zero, or even remaining constantly in the vicinity. If there’s a trend, it shows up for real over any large data set. I imagine there’s a probability distribution somewhere here as well.
There’s something in this line of thinking that could prove disasterous for the AGW crowd if they want to claim 1 or 2 or even 5 degrees of warming per century. (Although the proprietor of this website and the regulars here have provided more than a few disasters for the warmists already).
One day, when we fully understand what drives climate, we will have a good number to define a period associated with climate. Until then, we may as well be arguing about angels and pinhead. Eleven years is good for now, because it encompasses one complete sunspot cycle, on average. At least it has some basis in physical reality and balances the effects of a sunspot cylcle. Maybe 33 yrs will turn out to be right.
“Is there a formal meteorological/geological definition for the number of years encompassed by the term, “climate?” Roughly how many years does it take to shift from one set of climate averages to another, and how is that related to the duration of the “stable” climate periods? ”
Benoit Mandelbrot, who is a mathematician, and who knows something about chaotic systems, considered that question and there is a summary of his conclusions at Climate Audit. To over-simplify: its Weather, all the way down.
http://www.climateaudit.org/?p=396