Global warming underestimated?

By: Dr. Jeff Masters , 3:00 PM GMT on February 10, 2006

Are the official estimates of a 1.4° to 5.8°C (2.5° to 10.4°F) increase in global mean surface temperatures by the year 2100 significantly in error? That was the conclusion of MIT professor Dr. Peter H. Stone, in a lecture I attended last week at the annual meeting of the American Meteorological Society. Dr. Stone's results were also published January 13, 2006 in Geophysical Research Letters. The "official word" in the science of climate change comes from the United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC), a collaborative effort between over 2,000 scientists from over 100 countries, including many of the top climate researchers in the U.S. The IPCC publishes an extensive assessment of the state of the science every six years. The most recent report, issued in 2001, predicted the 1.4° to 5.8°C increase. If Dr. Stone is right, the next IPCC assessment, due out in 2007, will have to revise that estimate upwards.

Dr. Stone started his talk by posting this quote from the Executive Summary of the 2001 IPCC model evaluation chapter: "Confidence in the ability of models to project future climates is increased by the ability of several models to reproduce the warming trend in 20th century surface air temperature when driven by radiative forcing due to increasing greenhouse gases and sulphate aerosols." (The term "forcing" in climate research refers to any process, natural or human-caused, that "forces" the climate to respond in a significant way.) The IPCC report supported their statement by comparing climate simulations of the observed 20th century climate that used just natural processes ("forcings" such as volcanic eruptions and natural changes in the sun's brightness) with simulations done including human-caused "forcings" (greenhouse-effect gases added since pre-industrial times, plus aerosol particle pollution). Dr. Stone presented Figure 4 (below), a modified version of a figure from the 2001 IPCC report. The figure shows a typical 20th century climate simulation by one of the major climate models used for the IPCC assessment--the UK Hadley Center model. The results look good. The model is able to reproduce the observed climate of the 20th century. In addition, the simulation shows that one cannot explain the observed 20th century global warming of 0.6°C without including human-caused (anthropogenic) climate forcings.

Dr. Stone argued that the IPCC's confidence in the ability of models such as the UK Hadley Center Model to predict future climate was invalid, and that the good agreement between the observed climate and model prediction seen in the figure above could have been coincidence. He outlined several ways that compensating errors in two or more areas of model uncertainty could have produced a climate simulation that matched the observed 20th century record.

Major uncertainties in climate change computer models include:

1) Climate Sensitivity (how much global surface temperature changes when CO2 is doubled)
2) Rate at which the oceans take up heat
3) Strength of forcing by aerosol particles
4) Natural variability

For example, if a model has a Climate Sensitivity that is too great (the model predicts too much warming for a given increase in CO2), and improperly assumes too much cooling will occur due to pollution from aerosol particles, the two errors will cancel each other out and lead to a realistic-looking simulation. The Climate Sensitivities of the 11 key models used to generate the 2001 IPCC results varied by about a factor of 2.5, from 1.5°C to 4.5°C. Similarly, the amount of heat taken up by oceans varied by about a factor of 2.5 in the models. Additional uncertainties exist in the models' treatment of aerosols and natural variability.

Rather than dismiss the climate models as being too filled with uncertainty to be useful for performing climate simulations, Dr. Stone maintained that one can do an intelligent uncertainty analysis by varying two of the major uncertainties in a model simultaneously, and study the resulting model predictions. He described his group's research to evaluate the uncertainties in 11 of the key models used to formulate the 2001 IPCC climate report. The study was done using data from the Coupled Model Intercomparison Project (CMIP), an international research program begun in 1995. The talk then became quite technical, with several plots showing Probability Distribution Functions on parameter-space diagrams. It was at this point I bemusedly watched the audience member next to me who hadn't had enough cappuccino that morning repeat the classic pecking bird "doze-droop-jerk-I'm awake!" pattern. Meteorology talks aren't always filled with captivating displays of 3-D Category 5 hurricanes! There's a lot of hard science needed to understand the concepts.

Finally, Dr. Stone finished his uncertainty analysis, and he presented some rather startling conclusions:

1) Models have been over-estimating the rate of mixing of heat into the deep ocean.

2) This implies that their projections of surface warming for the 21st century are too low.

The guy next to me jerked fully awake now, and the audience got noticeably more attentive. "And this worries me," Dr, Stone continued. "It worries me enough that we've made many extensive tests of our methodology that try to make sure that there are no flaws. I would be delighted if anybody here could come up with a test that we might look at to see if we've done anything wrong." The audience, filled with several hundred people, including many of the world's foremost climate experts, was silent. No one could come up with a reason to dispute Dr. Stone's gloomy conclusion.

So how much in error are the climate models? Dr. Stone didn't give a number in his talk, and when I asked him about this later he said he had only a rough preliminary idea of what this error might be. His research team is currently analyzing their results to see how much additional warming we can expect. When they publish some specific error estimates, I'll be sure to post a follow-up blog on the subject.

Professor Stone's talk can be heard on-line for free. To do so, you must install the free WebEx player for IE or Netscape. Note: this will not work for other browsers, such as Firefox! The talk is about 40 minutes long, and includes figures. Alternatively, you can read the paper on the subject that he co-authored along with C.E. Forest and A.P. Sokolov of MIT's Joint Program on the Science and Policy of Global Change:

Forest, C.E., P.H. Stone, and A.P. Sokolov, "Estimated PDFs of climate system properties including natural and anthropogenic forcings", Geophysical Research Letters, 33, L01705, doi:10.1029/2005GL023977, 2006.

A free abstract of the paper is available from the website. A full version costs $9 for non-subscribers.

A note on my global warming blogs
In an issue as complex, contentious, and important as global warming, it is impossible for anyone to present an unbiased and fair treatment of the subject. My bias will be towards presenting new scientific findings published in peer-reviewed journals, as well as calling attention to the political aspects of the debate when it appears that one side or the other is attempting to twist or hide the truth. While thus far I have only focused on the NASA/Dr. James Hansen affair, I also have criticism of those claim that Hurricane Katrina was significantly enhanced by global warming. Although it is possible that global warming did contribute significantly to Katrina's intensity, the current best hurricane science supports only a 1-2 mph enhancement in Katrina's winds by global warming. I have a blog on this topic I plan to post next week, highlighting recent questionable statements by the editor of Science magazine on the matter.

For those of you following the NASA/Dr. James Hansen affair, see this morning's New York Times article, where George C. Deutsch, the young NASA press aide who resigned on Tuesday amid claims that he had tried to keep Dr. James Hansen from speaking publicly about global warming, defends himself publicly.

A note on media bias on the global warming issue
I'm of the opinion that articles in the New York Times on global warming tend to be biased in favor of dramatizing the problem and calling for action. Articles in the Wall Street Journal, Washington Times, and Newsweek magazine generally have the opposite bias. Time magazine seems pretty neutral, and may have a pro-action bias. I'm not sure about the USA Today, Washington Post, or other sources. One of my favorite sources of global warming info (but a little too technical for many readers) is from, which is maintained by some of the top climate scientists in the field. They have serious disagreements with the Wall Street Journal.

Jeff Masters

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177. hurricanecrab
9:25 PM EST on February 10, 2006

I haven't seen any verifiable test data relational to NOx and SOx and the ozone. It would be interesting to study it on a micro scale. SO2 is usually oxidized to (SO4)-2 before it forms an aerosol....

There seems to be a lack of very much empirical test data for much of these interactions. It's been a hobby of mine for nearly 10 years. Even the CO and CO2 density is hard to pin down globally.

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176. ForecasterColby
2:27 AM GMT on February 11, 2006
Pretty sure volcanic activity makes both sulfates and sulfides...but we make a heck of a lot more than a volcano.

NOX and SOX?
174. KatrinaRitaWilmaZeta
6:03 PM PST on February 10, 2006
this to yet ever one no the nhc as done 20 updates so foar and 7 more update to go
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173. hurricanecrab
8:55 PM EST on February 10, 2006
hmmmmmm. Now this is particularly interesting to me. From Dr. Masters' blog above: Dr. Stone started his talk by posting this quote from the Executive Summary of the 2001 IPCC model evaluation chapter: "Confidence in the ability of models to project future climates is increased by the ability of several models to reproduce the warming trend in 20th century surface air temperature when driven by radiative forcing due to increasing greenhouse gases and sulphate aerosols

sulphate aerosols? Maybe I'm way off base here, but it seems that should be sulfide. I would think that sulphate aerosols would be mostly a product of 'natural' Earth systems -- volcanos... sea salt/sea life interaction, etc.

okay, okay, so it's been 25 years since my last chem. class. I tried to keep abreast of everything. *L
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172. Skyepony (Mod)
1:53 AM GMT on February 11, 2006
checkout the NWS watches, warnings & what nots page. Got a lot of area looking for snow ~ New Hampshire to Mississippi & seperately the Dakotas. Red flags & fire weather watch areas have grown in the last few days as well.
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171. hurricanechaser
1:46 AM GMT on February 11, 2006
This will be my last post tonight.

I went back and look through some of my posts and although I never understood why so many were assuming I am arrogant of all things, it soon became obvious to me by some of my inappropriate posts.

I too hate arrogance and the idea someone is better than another for any reason, yet I have only myself to blame for creating that perception.

In short, I want to publically apologize for starting the personal attacks on Weatherguy03 (Bob) when I questioned whether he was a real meteorologist. I belueve we can all agree that he is and a real blesing to the community as a result.:)

I have spent alot of time tonight doing some soul searching and reading posts and I am honestly ashamed of my attitude recently which I was blinded to honestly.

It is amazing how perception can become reality. Although, I have been so offended by attacks I know aren't true, I can see why one could make those asumptions based solely on my own actions at times.

In short, I have learned alot today and I'm sorry I took up much of this blog to do so.

Well, goodnight everyone.:)

Your friend,

170. sayhuh
1:50 AM GMT on February 11, 2006
Trouper415, as TPaul and I were discussing previously, looks like this will be a doozy storm! I think there is enough moisture being picked up, along with the temps...not sure I would want to be anywhere on the east coast without skis!
168. hurricanechaser
1:33 AM GMT on February 11, 2006
Cyclone buster,

I will go on record to say I'm not very knowledgable in that area to say whether your idea will or will not work. That being said, I would encourage you to seek out those who work in that field full time.
166. KatrinaRitaWilmaZeta
5:31 PM PST on February 10, 2006
my new blog is a so come on by the water is hot
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165. Trouper415
1:30 AM GMT on February 11, 2006
Good post Dr Masters.
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164. Trouper415
1:30 AM GMT on February 11, 2006
If that storm down south turns to snow when it reaches the east coast, thats going to be one hell of an event.
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163. hurricanechaser
1:18 AM GMT on February 11, 2006
I will be completely honest and state that a part of me would be disappointed not to ever experience another category three storm. I'm not saying that is right, but I believe I'm not alone in that sentiment. Although, no one wants death or the destruction that comes along with it.
162. hurricanechaser
1:16 AM GMT on February 11, 2006
I have an interesting question and wonder what the answers would be if everyone answered this question honestly.

Would anyone in here be disappointed if cyclonebusters tunnel idea was very feasiable and actually could prevent another category three hurricane or higher?
161. hurricanechaser
1:16 AM GMT on February 11, 2006
I'm with you wholeheartedly cyclone.:)
160. hurricanechaser
1:15 AM GMT on February 11, 2006
Please read my new blog just posted, before making any other statements regarding my actions the past couple of days, please?:)

158. hurricanechaser
1:06 AM GMT on February 11, 2006
what do you call all the anti=Christian attacks? It's ironic how people can engage in bigotry against Christians and call them all kinds of horrible names yet let a Christian respond with the Biblical view on a sin such as homosexuality and we get called bigots.

Once again, I am no better than anyone else whether homosexual, liar, murderer, adulterer, etc. I am not without sin either but I am not making excuses for my sins and saying if you point out it is wrong for me to have an affair on my wife that you are a bigot against adulterers.

148. KatrinaRitaWilmaZeta
4:03 PM PST on February 10, 2006
yes Get A Grip People it is friday
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147. haydn
11:32 PM GMT on February 10, 2006
Look what is coming to Alabama and Georgia. Hope you got your rain gear. I'll get it a few hours later.
146. haydn
11:15 PM GMT on February 10, 2006


Keep posting. I am.

I noticed you are calculating the volume of the atmosphere.

At 62 mile height 1.24x10^10 miles cubed

At 6.8 miles 1.4x10^9 miles cubed
All agree?

In case anyone hasn't noticed, I like math stuff.

145. hpbear
6:20 PM EST on February 10, 2006
thanks.... that's all I needed to know...

especially with all the assumptions that are used to come up with the models, from ideal gas to hydrostatics.
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144. tornadoty
11:18 PM GMT on February 10, 2006
Colby, I love this forecasting thing. I made the first post there. Also, I would like to talk to you about possibly setting up a severe weather forum on your site. I know it's the Amateur Hurricane Center, but maybe it could be made into the Amateur Weather Center. Also, I have a tremendous forecast game I came with, which may be the absolute nightmare scenario for the United States, and I would like to make that the basis for the next game.
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143. Esarhaddon
10:49 PM GMT on February 10, 2006
hpbear ...

the combined gas laws only work for an ideal gas. since, the atmosphere is a mixture of real gases, use of the ideal gas law only gives appoximations. the atmosphere never acts as an ideal gas, so there are lots of more complicated gas law equations for the description of real gases (van der waals equation, and others).

To answer your question about R ... R was not determined using the atmosphere, so a change in CO2 would not change R.

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142. hpbear
5:43 PM EST on February 10, 2006
actually, the levels were at something like 250 ppm when they started measuring on some mountain top in hawaii back in the early 1900's, and are now something like 380ppm, which is the increase I am talking about. it's supposed to rise further to something like 500-700 ppm, depending on the climate model. I know that's still a small amount compared to the atmosphere as a whole. but the increase that has already happened suposedly brought about the warming we are already seeing.

Not saying that maybe unusual sunspot activity or other space matters may be affecting things more or less, but that's all stll being studied.

I know it's just a thought, and maybe even a theory. But even foreasters can think of abstracts like that once in a while. that's why there are those in thermodynamics, micrometeorology, and atmospheric chemistry who could look at this.
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141. ForecasterColby
10:51 PM GMT on February 10, 2006
Stormchaser, I don't think so at all. Wanting to improve the discussion here is not egotistical at all, it's not wanting to lose one of the best communities on the web.

If anyone would like to have a little fun, I'm doing a little fantasy storm contest on my site. Basically, I'm "playing" the storm based on a few past systems, and you guys try and predict. I remember it being a lot more pleasant around here during summer (when we were all excited about hurricanes) so maybe it'll help. I dunno.
139. jeffB
10:37 PM GMT on February 10, 2006
hpbear wrote:

Well, with the changing composition of the atmosphere, mainly in the CO2 department, causing a spike in the heat balance; could the otherwise constant R actually be changing, with that causing changes to some of the other equations that govern meteorology?

It don't think it should, but with all the talk of the atmospheric composition of CO2 being almost 30% above levels when the constants were first established, and the CO2 levels being forecast to be even much higher, I could think that the constants may change with time and maybe toss the models into enough of a problem to make them more unrelaible.

Given that the concentration of CO2 in the atmosphere is something like 0.04% by volume (0.06% by weight), it seems unlikely. The hypothesized 30% increase would raise this to 0.05%, not 30.04%, of course. :-)

Disclaimer: I never even took p-chem, much less advanced thermo.
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138. gippgig
10:32 PM GMT on February 10, 2006
R is a constant that cannot vary. However, PV=nRT is only true for the theoretical "ideal gas". Real gasses vary slightly. Changing the composition of a gas does change its behavior but the effect is fairly small (particularly at lower pressures like the atmosphere). Carbon dioxide is only present in a few hundred parts per million so significant changes in its level are unlikely to significantly change the properties of the atmosphere but it is an interesting idea.
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137. ForecasterColby
9:43 PM GMT on February 10, 2006
I was calculating the volume of the atmosphere.

Again, I won't be posting for the next few days until either this calms down or I give up on the community here.
136. hurricanechaser
10:16 PM GMT on February 10, 2006
To Everyone else,

I have to objectively think that my current stressful living situation might just have me very emotional. I read all of my posts from last night through today and see a tone in my comments that I don't personally like regardless of the fact I stand by my convictions made in them.

Therefore, I sincerely apologize for the tone of those cpmments and regardless of the reason(whether it be my living arrangements or not)was inappropriate and confrontational. On the other hand, that tone changed with the discussion of religion and my believes and I have no apologies for those coments and only shared my PERSONAL beliefs when asked about them which I believe was and is the right thing to do.

In short, I hope each of you has a great night and a good weekend.:)


135. hurricanechaser
10:04 PM GMT on February 10, 2006
Dr. Masters,

It seems pretty apparent that we are on different sides of what is the DIRECT cause of global warming and possibly the political views as well. That being said, I want to once again PUBLICLY apologize to you for making it personal as evident in my emotion investd first post last night.

I hope you understand why concern was the undeserved characterizations of Mr. Deutsch that are in doubt which if we were accused of something we MIGHT not have done would not appreciate.

I went WAY OVERBOARD in my response to your blogs and for that I sincerely apologize. I believe it is quite obvious I will only apologize when I believe I have done something I personally believe was wrong. Otherwise, I stand by my convictions regardless of anyones opinions.

I have to applaud todays post in that you did mention that Mr. Deutsch says he is innocent and I take that as being more objective than your post last night.`


132. hpbear
4:55 PM EST on February 10, 2006
just a scientific curiosity here, so please bear with me, this may be highly theoretical...

with all the discussion about increased CO2 levels and the like, i just have a scientific thought here that may be something for everyone to think about....

In the combined gas laws, PV=nRT. And when doing things like uniform gas expansion or compression (p1v1/n1R1T1) = (p2V2/n2R2V2), usually n1=n2 and R1=R2, so they cancel each other out.

Well, with the changing composition of the atmosphere, mainly in the CO2 department, causing a spike in the heat balance; could the otherwise constant R actually be changing, with that causing changes to some of the other equations that govern meteorology?

It don't think it should, but with all the talk of the atmospheric composition of CO2 being almost 30% above levels when the constants were first established, and the CO2 levels being forecast to be even much higher, I could think that the constants may change with time and maybe toss the models into enough of a problem to make them more unrelaible.

Am I thinking way too theoretically, or is this actually possible?
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131. hurricanechaser
10:01 PM GMT on February 10, 2006
Hey cyconebuster,

point well taken.:)

Honestly, I owe you a sincere apology for mocking your tunnel idea. I caught up in the global warming debate and lost sight of the fact you truly mean well by your tunnel concept. As a result, it is wrong for me or anyone else to make fun of your well intentioned idea.

We can disagree about the DIRECT cause of global warming or even whether your tunnels will work, but none of us should ever make a joke about your wel intentioned idea which I have done in the past.


130. hurricanechaser
9:59 PM GMT on February 10, 2006
Thanks Fsshead,

You know I like you personally even if we don't always agree (lol)for the person you are.:)

Your friend,
128. phelp
9:57 PM GMT on February 10, 2006
Hey guys,
In the spirit of the recent conversation, I've got a joke I think everyone can enjoy.

Q. What's the difference between Jesus and a picture of Jesus?
A. It only takes one nail to hang a picture of Jesus.

Hope that brightened everyone's day!
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127. Fshhead
9:56 PM GMT on February 10, 2006
Gotta go to work BUT, I will definitly come back after to see how the war is going LMAO!!!!!!!!!
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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