Statisticians: "Global Cooling" a Myth

Claims about Last 10 Years Are Deceptive; Temperatures Rise and Fall, But Overall Trend Is Higher

(AP)  Have you heard that the world is now cooling instead of warming? You may have seen some news reports on the Internet or heard about it from a provocative new book.

Only one problem: It's not true, according to an analysis of the numbers done by several independent statisticians for The Associated Press.

The case that the Earth might be cooling partly stems from recent weather. Last year was cooler than previous years. It's been a while since the super-hot years of 1998 and 2005. So is this a longer climate trend or just weather's normal ups and downs?

In a blind test, the AP gave temperature data to four independent statisticians and asked them to look for trends, without telling them what the numbers represented. The experts found no true temperature declines over time.

"If you look at the data and sort of cherry-pick a micro-trend within a bigger trend, that technique is particularly suspect," said John Grego, a professor of statistics at the University of South Carolina.

Yet the idea that things are cooling has been repeated in opinion columns, a BBC news story posted on the Drudge Report and in a new book by the authors of the best-seller "Freakonomics." Last week, a poll by the Pew Research Center found that only 57 percent of Americans now believe there is strong scientific evidence for global warming, down from 77 percent in 2006.

Global warming skeptics base their claims on an unusually hot year in 1998. Since then, they say, temperatures have dropped - thus, a cooling trend. But it's not that simple.

Since 1998, temperatures have dipped, soared, fallen again and are now rising once more. Records kept by the British meteorological office and satellite data used by climate skeptics still show 1998 as the hottest year. However, data from the National Oceanic and Atmospheric Administration and NASA show 2005 has topped 1998. Published peer-reviewed scientific research generally cites temperatures measured by ground sensors, which are from NOAA, NASA and the British, more than the satellite data.

The recent Internet chatter about cooling led NOAA's climate data center to re-examine its temperature data. It found no cooling trend.

"The last 10 years are the warmest 10-year period of the modern record," said NOAA climate monitoring chief Deke Arndt. "Even if you analyze the trend during that 10 years, the trend is actually positive, which means warming."

The AP sent expert statisticians NOAA's year-to-year ground temperature changes over 130 years and the 30 years of satellite-measured temperatures preferred by skeptics and gathered by scientists at the University of Alabama in Huntsville.

Statisticians who analyzed the data found a distinct decades-long upward trend in the numbers, but could not find a significant drop in the past 10 years in either data set. The ups and downs during the last decade repeat random variability in data as far back as 1880.

Saying there's a downward trend since 1998 is not scientifically legitimate, said David Peterson, a retired Duke University statistics professor and one of those analyzing the numbers.

Identifying a downward trend is a case of "people coming at the data with preconceived notions," said Peterson, author of the book "Why Did They Do That? An Introduction to Forensic Decision Analysis."

One prominent skeptic said that to find the cooling trend, the 30 years of satellite temperatures must be used. The satellite data tends to be cooler than the ground data. And key is making sure 1998 is part of the trend, he added.

It's what happens within the past 10 years or so, not the overall average, that counts, contends Don Easterbrook, a Western Washington University geology professor and global warming skeptic.

"I don't argue with you that the 10-year average for the past 10 years is higher than the previous 10 years," said Easterbrook, who has self-published some of his research. "We started the cooling trend after 1998. You're going to get a different line depending on which year you choose.

"Should not the actual temperature be higher now than it was in 1998?" Easterbrook asked. "We can play the numbers games."

That's the problem, some of the statisticians said.

Grego produced three charts to show how choosing a starting date can alter perceptions. Using the skeptics' satellite data beginning in 1998, there is a "mild downward trend," he said. But doing that is "deceptive."

The trend disappears if the analysis starts in 1997. And it trends upward if you begin in 1999, he said.

Apart from the conflicting data analyses is the eyebrow-raising new book title from Steven D. Levitt and Stephen J. Dubner, "Super Freakonomics: Global Cooling, Patriotic Prostitutes and Why Suicide Bombers Should Buy Life Insurance."

A line in the book says: "Then there's this little-discussed fact about global warming: While the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased."

That led to a sharp rebuke from the Union of Concerned Scientists, which said the book mischaracterizes climate science with "distorted statistics."

Levitt, a University of Chicago economist, said he does not believe there is a cooling trend. He said the line was just an attempt to note the irony of a cool couple of years at a time of intense discussion of global warming. Levitt said he did not do any statistical analysis of temperatures, but "eyeballed" the numbers and noticed 2005 was hotter than the last couple of years. Levitt said the "cooling" reference in the book title refers more to ideas about trying to cool the Earth artificially.

Statisticians say that in sizing up climate change, it's important to look at moving averages of about 10 years. They compare the average of 1999-2008 to the average of 2000-2009. In all data sets, 10-year moving averages have been higher in the last five years than in any previous years.

"To talk about global cooling at the end of the hottest decade the planet has experienced in many thousands of years is ridiculous," said Ken Caldeira, a climate scientist at the Carnegie Institution at Stanford.

Ben Santer, a climate scientist at the Department of Energy's Lawrence Livermore National Lab, called it "a concerted strategy to obfuscate and generate confusion in the minds of the public and policymakers" ahead of international climate talks in December in Copenhagen.

President Barack Obama weighed in on the topic Friday at MIT. He said some opponents "make cynical claims that contradict the overwhelming scientific evidence when it comes to climate change - claims whose only purpose is to defeat or delay the change that we know is necessary."

Earlier this year, climate scientists in two peer-reviewed publications statistically analyzed recent years' temperatures against claims of cooling and found them not valid.

Not all skeptical scientists make the flat-out cooling argument.

"It pretty much depends on when you start," wrote John Christy, the Alabama atmospheric scientist who collects the satellite data that skeptics use. He said in an e-mail that looking back 31 years, temperatures have gone up nearly three-quarters of a degree Fahrenheit (four-tenths of a degree Celsius). The last dozen years have been flat, and temperatures over the last eight years have declined a bit, he wrote.

Oceans, which take longer to heat up and longer to cool, greatly influence short-term weather, causing temperatures to rise and fall temporarily on top of the overall steady warming trend, scientists say. The biggest example of that is El Nino.

El Nino, a temporary warming of part of the Pacific Ocean, usually spikes global temperatures, scientists say. The two recent warm years, both 1998 and 2005, were El Nino years. The flip side of El Nino is La Nina, which lowers temperatures. A La Nina bloomed last year and temperatures slipped a bit, but 2008 was still the ninth hottest in 130 years of NOAA records.

Of the 10 hottest years recorded by NOAA, eight have occurred since 2000, and after this year it will be nine because this year is on track to be the sixth-warmest on record.

The current El Nino is forecast to get stronger, probably pushing global temperatures even higher next year, scientists say. NASA climate scientist Gavin Schmidt predicts 2010 may break a record, so a cooling trend "will be never talked about again."

[EndlessFormsMstBeautiful]

An open letter to Steve Levitt: http://www.realclimate.org/index.php/archives/2009/10/an-open-letter-to-steve-levitt/

[Bill_Pa]

"If you want a loo-o-o-ng trend then what about a trend beginning in
the Roman Warm Period, a 2000 year trend? That shows a terribley[sic]
cooling trend."

Bunk: See http://www.realclimate.org/images/m08.jpg
You have perhaps a gradual cooling up to about 1850, then several
times that amount of warming afterward.

You're pretty authoritative in your dismissal of the Roman Warm, and the Medieval Warm Periods. Is your recitation of climate history also based on the linked graph?

[j_mcdonald-2009]

If you have a point to make, show me your data. Otherwise I have no idea what you think
you're referring to.

The linked graph is just one of many I could have picked, but includes data from several
different sources and is relatively easy to read. It's drawback is that it's just the northern
hemisphere, but I was a bit rushed to find a global one for that time period.

[CarlosWMoreno]

AP,
It is much more relevant to reference heating/cooling to the long term heating that has been taking place since 10000 and 400 years ago, as this is the only relevant information to guide any political / economic decisions. It is obvious that humankind cannot control what nature does at that scale.
Thus, ignoring this factor makes the analysis suspicious, and continues feeding the skeptics. The real question should have been: is there statistical evidence that the earth has become cooler than the natural temperature rise?
Carlos W. Moreno

[j_mcdonald-2009]

What are you talking about? There was no long term heating trend, neither from 10,000 nor from 400 years ago, unless you count the heating from 1850 to the present.

If you have data, please cite it.

[Achuara]

McDonald, stick to your hamburgers. Trends can be whatever you want. If you want a loo-o-o-ng trend then what about a trend beginning in the Roman Warm Period, a 2000 year trend? That shows a terribley cooling trend. But during the 20th Century we had four cooling and four warming trends of about 30 years each. It is all about solar cycles. The irrefutable data analysis of the past 150 years clearly indicates the existence of a 230-year-cycle and a 65-year-cycle, in addition to the larger 1000-year-cycle. Since all three cycles had their maxima around the year 2000 the number of relatively warm years was quite natural.
If these trends continue we will see decades of cooling in the future. Try to get into astrophysics and astronomy and read about Jovian cycles, barycenters, strong correlations between deep solar minima as the Maunder, Wolff, Spöerer, Dalton, etc, and deep coolings. The present solar minimum compares with the Dalton (1795-1823) and astronomers --a bad word in the AWG debate, I know :-), are predicting a 50-90-year deep cooling. And that really are bad news.

[j_mcdonald-2009]

"Trends can be whatever you want."

Only for those seeking "creative interpretations" (I'm being polite.)

There are standard statistical methods used to separate signal from
noise, the simplest being low-degree polynomial curve fitting using
something like a least squares fitting. Using Occam's razor, that's
where one should begin unless there are convincing reasons to do
otherwise. One should also look at periods that are significantly
longer than the typical periods of known noise factors. Since El Nino
and similar oscillation events last for about 1 to perhaps 5 years,
"trends" of less than about 10 years start to become meaningless.

"If you want a loo-o-o-ng trend then what about a trend beginning in
the Roman Warm Period, a 2000 year trend? That shows a terribley[sic]
cooling trend."

Bunk: See http://www.realclimate.org/images/m08.jpg
You have perhaps a gradual cooling up to about 1850, then several
times that amount of warming afterward.


When you attempt to fit simple curves to the global temperatures for
time periods that span 1850 you get a lot of variance (i.e. a poor
fit). But if you split the data into two curves, one from the distant
past (anywhere from 400 to 600,000 years ago) up to 1850, and another
from 1850 to the present, you get two distinct curves each with much
lower variance. And further splitting doesn't reduce the variance by
much. That indicates something very significant and unique happened
abound 1850 that initiated a new regime. The dramatic rise in
atmospheric CO2 that began then is both highly correlated (about
0.96!) and makes physical sense as an explanation, so it is the
obvious candidate explanation. Nothing else comes close.

"But during the 20th Century we had four cooling and four warming
trends of about 30 years each. It is all about solar cycles. The
irrefutable data analysis of the past 150 years clearly indicates the
existence of a 230-year-cycle and a 65-year-cycle, in addition to the
larger 1000-year-cycle. Since all three cycles had their maxima around
the year 2000 the number of relatively warm years was quite natural."

You provide no evidence, but I assume you're referring to
"Phenomenological solar signature in 400 years of reconstructed
Northern Hemisphere temperature record", by Scafetta & West, since it
seems to be a current favorite among the denialists.

This has been thoroughly debunked. The authors made the gross error
of basing their conclusions on an ill-conditioned formula. (See any
text on numerical analysis for the definition of ill-conditioned, but
the basic idea is that an algorithm is ill-conditioned when small
variances in the arguments lead to large variances in the answers.)
When their methodology is applied to data from other centuries it
predicts the 20th century would warm by one thousand degrees!

There was something of a cooling trend from 1940 to 1970, coincident
with vastly increased aerosol releases post WW2. But even that is
best described as more of a lull in the heating as opposed to actual
cooling if you look at global temperatures and not just the northern
hemisphere.

More signficantly, note that many glaciers disappearing now have
persisted for several hundred thousand years. This pretty much
completely discredits the notion that the cycles you allude to are
terribly significant, or such glaciers would not have survived through
several earlier coincident maxima. Something is happening now that
has not occurred in over a million years, and searching for magic
cycles to explain it smacks of desperation.

"astronomers --a bad word in the AWG debate, I know :-), are
predicting a 50-90-year deep cooling. "

And which astronomers would that be?

[I might not have a chance to post again for the next several days, so
my apologies in advance if I can't reply quickly to any reply you
might have.]

[Achuara]

If you had a statistician a set of data and have them look for trends, they will look for a trend in the whole set. I would bet that they didn?t ask if there were any recent short term trends. Were the statisticians asked whether there is a trend over the last five years for example. If there is, is it a warming or cooling trend? It appears to me that the current warming trend started around 1910. Using their method of trend finding, we would have to have cooling comparable to the last 5 years for many decades before there would be a long term cooling trend. Even if they want to look at the most recent warming period in isolation, it would probably take decades for a linear regression starting around 1980 to show a cooling trend. The ?blind test? might have been blind to the statisticians but if the question was not about the last five years or so, the results were preordained.

If 2008 was COOLER than 2007, and 2007 was COOLER than 2006, and 2006 was COOLER than 2005, then THERES Is A COOLING TREND.

[j_mcdonald-2009]

Achuara, you're right. It was 75 degrees yesterday and only 72 degrees today, so we are definitely in a cooling trend.

"Trend" implies something more than 4 or 5 years.

[doc_holliday76]

by mica1884:
"...it is dead set against modern/industry, technology, and capitalism. As the saying goes "Green is the new red."
--------------------------------------------





Heavens NO.....you have it backwards, since the DENIALISTS have been pushing antiquated technology of burning fossil fuels without any regard to the massive greenhouse gas emissions.

On the other hand, those that can see the harm being done to our environment, are pushing RENEWABLE ENERGY that produces no harmful greenhouse gases and is free from the sun and wind, and newer technology that captures CO2 from fossil fuel emissions such as coal-burning electricity plants, and grows OIL-producing algae that thrive on the CO2 and can be harvested for biofuels -- a win/win situation.

Modern industry must evolve with the times, and not be resigned to living in the past as the constipated conservitards would wish!

[doc_holliday76]

"Of the 10 hottest years recorded by NOAA, eight have occurred since 2000, and after this year it will be nine because this year is on track to be the sixth-warmest on record."
---------------------------------------




by redrightreturn:
"The trick here is to say the last decade is the warmest ever in recorded history. Of course it is. The warming trend line has been going up in previous decades, then in the last decade, the globe stopped warming..."
----------------------------------------





Hmmmmmmm.....appears as if reading comprehension is not your strongest suit, especially since NOAA is saying that 2009 is on track to be the 6th warmest year, with 9 of the warmest years occurring since 2000. All graphs are still showing an overall warming TREND!

[sjc_1]

My comment about global cooling from the pollution caused by jet liners got removed from this site. It was discovered after the planes were grounded post 9/11. I guess the truth proven by fact is less important than rants.

[troutfishyman]

by louiville2_5 October 27, 2009 1:30 PM EDT


I would have more faith in the science if the energy bill actually had money for alternative energy development, but $1 billion is photo op money for politicians who just are greedy or are working for greedy people.




Now you have shifted to a political discussion, versus the factual basis for AGW. These are distinctly different animals, you know. I have no faith that politicians will get any of it right.

[troutfishyman]

by louiville2_5 October 27, 2009 12:56 PM EDT

Speaking of corruption what would $199 billion dollars a year up for grabs do for corruption? I mean people have been killed for forty dollars just think what they would do for $199,000,000,000,000 each year? They would lie, cheat, steal, kill...... for that. If you don't see that then you are a fool.

Don't mind me I'm just a little cynical about politicians of every flavor.



If you want to talk money, then you well know that the fossil fuel industry has spent many millions over the past 20 years to create doubt about AGW. They have funded the handful of professional skeptics out there, as well as donating millions to select politicians.

[rocketjl]

Please stop all the guessing. I have heard a lot about global warming being cause by man. These same people are refusing to say anything about global warming as a component of a natural earth cycle. They say man is putting too much junk in the air, but refuse to quantify the same global junk that is being spewed out of volcanoes everyday. These people seem more like they just want to draw attention to themselves. Hey, please be careful and truthful with what you say, every time you open your mouth, my bills go up and I see you on TV thumping you chest. Mom give them a kiss, god be quick.

[j_mcdonald-2009]

Over the last 100+ years, all the volcanos in the world together have put out about 1/150 of what man has released through burning fossil fuel. This is well documented in independent ways that all agree with each other, for example:

* direct measurements of volcanos vs. amount of CO2 released by man
* C14/C12 and C13/C12 ratios in atmospheric CO2 have both been dropping at rates that show fossil fuels are the most significant source of the CO2, followed by burning of recently created biomass, followed by CO2 from the oceans and volcanos
* etc.

Just because you haven't taken the few seconds it requires to Google "volcanos CO2" or "C14 global warming" and then read some of the articles, doesn't mean that thousands of scientists haven't studied this to death.

Stop confusing your laziness and ignorance with a lack of evidence.

[doc_holliday76]

by rocketjl:
"They say man is putting too much junk in the air, but refuse to quantify the same global junk that is being spewed out of volcanoes everyday."
---------------------------------------




by j_mcdonald-2009:
"Just because you haven't taken the few seconds it requires to Google "volcanos CO2" or "C14 global warming" and then read some of the articles, doesn't mean that thousands of scientists haven't studied this to death.

Stop confusing your laziness and ignorance with a lack of evidence."
-----------------------------------






Aaaaaah....but ignorance and laziness seem to be traits of the FAUX NoNooz crowd, where swallowing all of the glenn beck propaganda in order to parrot it later, is easier than using a search engine.

Besides, we don't have volcano eruptions daily, but we certainly have almost 7 Billion people on this planet with more cars each day and more needing electricity to power their HDTV.

[parisdakar]

"Statisticians say that in sizing up climate change, it's important to look at moving averages of about 10 years." 10 years?? Where do they get that from? Because a period of 10 years shows a global warning trend? Cherry picking goes both ways.

[j_mcdonald-2009]

If you don't like 10 years, use 5 years or 30 years, or 8 years. Just about anything that smoothes out the random yearly fluctuations will show the same long-term trend. There are hundreds of ways to smooth the data that show warming, including all of the most obvious choices, and only one or two highly contrived ways to get a cooling trend. Or didn't you read the article?

[Wolf1944]

A period of over 130 years shows a warming period. See the graphs on NASA's website or the ones on NOAA's website.

[troutfishyman]

by louiville2_5 October 27, 2009 12:36 PM EDT
louiville2_5

PS
I went all the way through Diff E in math on academic scholarship, finished with an MS. Doubt I need your remedial books. But thanks for thinking of me, old buddy.
==================================================================================

Ah but did you take linear algebra, numerical methods, Fourier transforms......




I do not claim to be a mathematician, merely pointing out I am not totally ignorant on the subject. I believe the point of this article is that they actually hired mathematicians to do an analysis of the data. Did you even READ the article?

[mica1884]

As far as I'm concerned, the whole reason behind limiting the range of data to the past 130 years should tell us all we need to know about the man-made global warming cult -- it is dead set against modern/industry, technology, and capitalism. As the saying goes "Green is the new red."

I seem to recall someone asking for links to petitions by the scientific community on this matter, well, here's one:

http://www.oism.org/pproject/

There is a more recent one somewhere out there rightly blasting the IPCC as the dog-and-pony show that it is, but I can't seem to find it at the moment.

Commence flaming and death threats, o ye true believers!

[j_mcdonald-2009]

http://www.oism.org/pproject/"

That petition is a complete joke. They claim 31K names of scientists but I doubt they have 10 (as in the number of my fingers). Everyone who has examined the list has declared it to be bogus.

I examined a random sample of 100 and found ZERO active scientists. I did find a lot of names that appear no where else on the internet (pretty bad track record for a "scientist"), a lot of retirees, a lot of people that died decades ago, etc.

Again, people, a little fact-checking goes a long way.

[dragon8me]

I've been reading excerpts from "The Republican War On Science" and it is so true. It seems they prefer to embrace ideology and reject sound science for political gain. Sure science is an ongoing process and not perfect, even Einstein and Hawkens had to admit they were wrong about some of their theories, but it's because of their theories that science advanced and found the answer that disproved their theories. When it comes to science that would cost corporations money and cut their profits, the right invents it's own "science", or when it goes against their religious ideas they come up with something like "intelligent design". I'm sure Adam had a pet saurapod or two. It's not their fault Noah wouldn't let them on the Ark. Or maybe God put their bones here and there to test their faith. He's susch a joker, the native Americans would have called Him Trister Coyote. The sad thing is no matter how much proof you have they will not listen unless it comes from the right, and even then if it's not in the bible they still wont believe it.

[doc_holliday76]

by dragon8me:
"I've been reading excerpts from 'The Republican War On Science' and it is so true. It seems they prefer to embrace ideology and reject sound science for political gain."
-------------------------------------------




Yep....and Chris Mooney clearly researched deeply for that book, especially the chapters on global warming and the religious right's need to go from "creationism" to "intelligent design" after the SCOTUS shot down their attacks on evolution as not having a separation between church and state.

It's all about having a need to carry more water for corporate America, thus the politics of science as anti-science by the republican'ts!



The Republican War on Science by Chris Mooney
A stinging indictment of how the Republican Party has not only ignored science, but has used bad science to justify its political agenda.
www.waronscience.com/

[troutfishyman]

louiville2_5

PS
I went all the way through Diff E in math on academic scholarship, finished with an MS. Doubt I need your remedial books. But thanks for thinking of me, old buddy.

[troutfishyman]

louiville2_5


I looked at all the papers you listed. None of them refute the basic premise of AWG, they just haggle around with methodologies. What is your point here?

[j_mcdonald-2009]

I think louivill's goal is monetary.

If I had to guess, I say he's getting paid by the post, but perhaps it's by the word.

It's hard to explain his posts otherwise.

[troutfishyman]

by louiville2_5 October 27, 2009 11:35 AM EDT
Hey troutfishyman I came across this book that might help you with the science:

http://www.amazon.com/Mathematics-Simple-Geologists-David-Waltham/dp/0632053453





Back at ya! Here are two for you to read:

Global Warming for Dummies
The Complete Idiot's Guide to Global Warming

http://www.amazon.com/Global-Warming-Dummies-Math-Science/dp/0470840986

[troutfishyman]

by louiville2_5 October 27, 2009 10:46 AM EDT

Just full of Ad hominem attacks but once again nothing of science to back them up. Just a phony facade................


LOL!!!!!!!!!! You are the one that uses blogs to try and make your point. Sad.

[dragon8me]

You know, in a way it dosn't matter who's right. What matters is right now we depend on a limited supply of fossal fuels. We should be developing renewable energy, like solar and wind, which we are to some extent. But what about the most abundant element in the universe? Hydrogen? It's easy to make and dosn't pollute. I remember when I lived in Tuscon a guy was making it in a swiming pool at a small community outside of Tuscon. The county shut him down saying it was dangerous. I have been pushing for Hydrogen power for over 30 years. It may not be the best for moving vehicles, unless it can be made on demand in a fuel cell but for stationary plants it would be perfect and you wouldn't have to change much. I worked in wastewater treatment and we produced all of our electricity on site. 30% of which came from the methane from our digesters. It's a dirty fuel but it's better to use it like this than vent it to the atmosphere. Dairy farms and any farm for that matter could be producing their own electricity and the sludge can be dried and used as furtilizer. The point is we need to be more effecient with what we have and quit wasting resorces.

[doc_holliday76]

by dragon8me:
"You know, in a way it dosn't matter who's right. What matters is right now we depend on a limited supply of fossal fuels. We should be developing renewable energy, like solar and wind, which we are to some extent."
-----------------------------------------------




Exactly!

And today's announcement by President Obama at Florida's grand opening of their largest solar facility, that also signals the use of stimulus funds to help build more grid infrastructure and matching dollars from private industry!

Unfortunately, all the republican't DENIALISTS have done for years is watch our infrastructure crumble, as they funneled more and more taxpayer dollars to endless WARmongering and the WAR PROFITEERS!