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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

Sign In or Register Sign In or Register

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 77 - 27

Page: 1 | 2 | 3 | 4 | 5Blog Index

77. TPaul
8:15 PM GMT on February 10, 2006
Now see what you have done HurricaneChaser, you have brought out Queen of the Rules.
Member Since: Posts: Comments:
76. ForecasterColby
8:13 PM GMT on February 10, 2006
This is getting ridiculous.
75. Sheraqueenofthebeach
3:09 PM EST on February 10, 2006
Can I remind folks the purpose of the main Blog?
Specifically Jeff Masters' blog?
This was posted bach during the heat of Hurricane season:
Hi all, let's review the rules we posted a while back on what to consider when posting comments here:

"I realize that hurricane time is an exciting time for a lot of people for many different reasons. Some people are worried about their property or their lives, others are interested in the nature of these majestic weather systems, others just really like the drama. All of that is fine, however prohibited language, threats, bickering, off topic chattering, etc. will no longer be tolerated in the featured blogs. Each user has their own blogs, to talk about whatever they desire so long as the content does not contain prohibited language and threats, etc. Please use those spaces, as well as the already existing private message system to communicate about material that does not belong in the featured blogs."
In particular, I would like to see the blog comment area have fewer "chit-chat" posts that belong in a chat area. It makes it very difficult for me to wade through endless long conversations to find legitimate questions I'd like to answer.
If there is a question you'd like me to answer, you're probably better off emailing it to me directly,

I encourage all of you to use the "spam" or "obscene" feature for a comment you'd rather not see. If five of you flag a comment, it will disappear until an admin looks at it and releases it. We have kicked a number of users off, but some of them keep coming back under new screen names, and there's really nothing we can do to permanently stop a determined person from creating havoc in a free open system like this.

Member Since: Posts: Comments:
74. sayhuh
8:11 PM GMT on February 10, 2006
72. ForecasterColby
7:58 PM GMT on February 10, 2006
Here's a good laugh for everyone (I know it's true because it's my story!):

OMG.............LOLOLOLOLOL. Can't believe I forgot to mention this one:

I was in Biology earlier, and the teacher had been fairly arbitrarily handing out candies to the class. Towards the end of the period, the guy next to me bursts out laughing, and tells everyone to read their wrapper. I look at mine and read:

Ingredients: Isomalt, Citric Acid (for tartness), Natural and Artificial Flavor, Sucralose, Artificial color (red 40, yellow 5, blue 1).
Excess consumption may have laxative effect.
71. WeatherWeasel
8:04 PM GMT on February 10, 2006
Wow....thought I was jumping in to read about the weather. This must be the Baptist convention...where do I find the discussions about weather, I must be in the wrong lecture hall...
Member Since: Posts: Comments:
70. TPaul
8:06 PM GMT on February 10, 2006
Ok, maybe its me, but I am beginning to think that there is an underlying intent of individuals here to make this a debate of religion. Can we get back to the debate on the serious topic of global warming and for our amusement "tunnels".
Member Since: Posts: Comments:
68. Cregnebaa
3:03 PM EST on February 10, 2006
Cheers F5 will take a look.
Member Since: Posts: Comments:
66. F5
8:00 PM GMT on February 10, 2006
Forecaster Colby,

Prior to Jesus and the New Testament, the only way to be obedient to God was to follow the prescribed laws of the Hebrews. For Christians, the New Testament shows us a new way to be in harmony with God, without all the religous rules that were in place during the Old Testament. Jesus came to show us the way. I certainly would not want to live under old testament rules.
Member Since: Posts: Comments:
65. jeffB
8:00 PM GMT on February 10, 2006
Good point, ForecasterColby. But since I had ham for lunch, and I'm wearing mixed-fiber clothing, I guess I'm automatically disqualified from commenting on the issue... :-)
Member Since: July 8, 2005 Posts: 0 Comments: 45
64. F5
7:53 PM GMT on February 10, 2006

Here is an interesting summary as well as a link to the actual study which talks about whether our measurements of the global temperatures are even accurate. This is a key element because if our measuring system is not accurate, we may be vastly overestimating the warming that is occurring.

Not CO2. Read the synopsis as well as the actual study.

Another interesting site is run by the Roger Pielke Research Group at Colorado State University. Roger Pielke blog. I will find you some additional sites as well. It does make for interesting reading from the other side.
Member Since: Posts: Comments:
63. ForecasterColby
7:57 PM GMT on February 10, 2006
F5...the bible prescribes death by stoning as punishment - a gay joke seems pretty mild by comparison :P
61. ForecasterColby
7:51 PM GMT on February 10, 2006
I'd least global warming is semirelevant to the weather.
60. jeffB
7:27 PM GMT on February 10, 2006
Y'know, I can't speak for anyone else, but in this particular forum I'd much rather read someone's views on global warming than his views on religion and sexuality. But that's just me. :-)
Member Since: July 8, 2005 Posts: 0 Comments: 45
59. ForecasterColby
7:48 PM GMT on February 10, 2006
In HillsboroughBay's post above.
58. Cregnebaa
2:47 PM EST on February 10, 2006
Where did you find that Colby?
Member Since: Posts: Comments:
57. ForecasterColby
7:45 PM GMT on February 10, 2006
There's a smile character? Okay, that's just cool ☺

56. ForecasterColby
7:41 PM GMT on February 10, 2006
Ozone and Global Warming are unrelated, at least if we're talking about fossil fuel use. CO2, though it isn't a very good insulator, is good enough, and we're producing a great deal of it. The primary Ozone destroyers are CFCs (chloroflorocarbons). Basically:

O3 (Ozone) + Cl (chlorine from CFCs) -> O2 + ClO
2 ClO -> Cl2 + O2
Sunlight + Cl2 -> Cl + Cl
55. Caymanite
7:34 PM GMT on February 10, 2006
I too would like to slip off of the observer bench to ask the cyclone buster to explain the mooring/floatation system that he proposes to use for his tunnels. If he is unable to explain this then I think that he should research it before claiming it to be the cure all and end all for every weather phenomena that exists.Thanks Dr. Masters for your blog and to all others for your very informative views."Buster" the average water depth half mile off-shore where I live is about 2000 ft.but I guess your tunnels wouldnt be deployed here anyway. L.O.L.
Member Since: Posts: Comments:
54. HurricaneMyles
7:37 PM GMT on February 10, 2006
Karen, I think everyone agrees on that. Clean air is good for everything. However, the solution(s) that some people have come up with costs lots of money which takes away from other investments and profit. People dont want to spend lots of money to stop spewing C02 and whatnot when they could be making money doing something else. So they fight it and try to defend their profit-making ways. I personally thinks a good thing that we should jump head-first into something whether we think its good or not; there always needs to be heathly debate.
Member Since: Posts: Comments:
53. HillsboroughBay
7:37 PM GMT on February 10, 2006
and will get back to my Weather 101 series the first chance I get..
How is this possible? You alsready left! So much for having priciples

Member Since: Posts: Comments:
52. SBKaren
7:31 PM GMT on February 10, 2006
Wow - what a heated blog we have here. Ok - I have a question. Whether our global warming trend is human induced or not, isn't it still bad for our air quality in general? So wouldn't we want to clean it up just for that reason alone??? Wouldn't having the cleanest air we can breathe be a top priority for anyone - regardless of what it is doing to the ozone? Just a simple thought, as I'm a pretty simple thinker.
Member Since: Posts: Comments:
51. Cregnebaa
2:32 PM EST on February 10, 2006
Tpaul I am with you on that one "influenced" would be the correct term in my opinion
Member Since: Posts: Comments:
50. TPaul
7:25 PM GMT on February 10, 2006
I say lets take little baby steps. Can we agree on weather it is Human Induced or Human Influenced Global warming. My vote goes with Influenced as I don't believe we started it. Of course I am assuming we all can agree that there is Global Warming going on, the issue is to what effect we are contributing to that. I also stay we stick with topics related to the weather and avoid other conservative/liberal topics that are just going to add heat to the arguments. But that is just my 2 cents.
Member Since: Posts: Comments:
49. Cregnebaa
2:29 PM EST on February 10, 2006
True Colby, but we're never going to have proof, the best we can do is use correlations.
Member Since: Posts: Comments:
48. ForecasterColby
7:26 PM GMT on February 10, 2006
Oh, there's plenty of evidence. But again, evidence does not mean proof.
47. hurricanechaser
7:22 PM GMT on February 10, 2006
Thanks so much Sayhuh and Colby.:) I realize that my sensitivity is both one of my greatest strengths and yet can be one of my greatest weaknesses as evidenced by my over sensitivity as of late.

Thanks for reminding me of what is truly most important in life.:)

Your friend,

46. TPaul
7:20 PM GMT on February 10, 2006
Cyclonebuster, I really am going to just assume that your tunnel idea is a big joke and that is the way you mean it because you are definitly not serious about what you say.
Member Since: Posts: Comments:
45. Cregnebaa
2:23 PM EST on February 10, 2006
Heated up quickly there.

Dont know how homosexuality got brought up, but isnt it mostly the old testament barraging it. Thought the New Testament was all about Love they Neighbour and he without sin cast the first stone, perhaps its unchristian to think like this, but that is my opinion.

Please if we start drifting on these topics well end up on Stem cell research and GM foods.

Again I reiterate on human induced global warming, why is it most other major industrial countries agree it is happening, when the is no evidence. Perhaps they believe the correlation is enough; perhaps they have better information than us, or perhaps they are run by stupid people who want to destroy their economies.
Member Since: Posts: Comments:
44. hurricanechaser
7:11 PM GMT on February 10, 2006
Whose rules? your opposition to an opposing view. I'm sorry that will never be the case. I stand up for what I believe is right no matter how many attack me or my OWN PERSONAL's called having principles.

I once again humbly ask that you try to be civilized and please accept a sincere apology on my part and a fresh start, is this possible?

please reread a couple posts down where I apologized for critisizing your forecasting abilities and I simply prefer peace and regret my part in all of this bickering.

As a result I will not post my opinions of global warming in here, but will do so in my friends, Fssheads blog instead.:)

I am more concerned with helping others learn about the weather than doing anything else on this blog in all honesty. I realized last night that I have gotten away from the real reason I first joined this site. I must say I've learned alot from many who aren't or haven't had professional experience like those such as Colby just for the record.

We all can learn from each other because we had to learn what we know from someone else to begin with. Therefore, how can we presume to be so superior when our own knowledge is mainly a product of oppotunity, personal experiences, and circumstances whether they are positiver or negative.

I for one will call it a day for awhile by sincerely apologizing for forgetting WHY I first joined and will get back to my Weather 101 series the first chance I get.


43. ForecasterColby
7:15 PM GMT on February 10, 2006
Okay, I have a new approach to argument stopping - take a look at this article we can all agree is ridiculous Link
42. sayhuh
7:10 PM GMT on February 10, 2006
Again, as an observer, but confident with what I have read over the last year, I have no problem expressing my support of Chaser and the passion he presents in his thoughts. Again, without that passion, taking a stand is rather futile. I don't agree with everything that is stated by either Chaser or others, but respect the vein in which is created. So, let me be the first say I am in support, and again, being an observer primarly, have no allegiance to anyone I have seen in this blog.
41. ForecasterColby
7:11 PM GMT on February 10, 2006
Personally, I would like chaser to stay if he can keep his temper in check. I think I speak for most of us.
39. weatherguy03
7:09 PM GMT on February 10, 2006
Yes I will be here to keep you in line. As long as you play by the rules, I will be nice. But get out of line and I will be here to remind you. And yes if anybody wants chaser to stay please e-mail me. Thank you.
Member Since: Posts: Comments:
38. ForecasterColby
7:07 PM GMT on February 10, 2006
Chaser, weatherguy, keep this up and I think a banning is likely.
37. ForecasterColby
7:05 PM GMT on February 10, 2006
If I knew the formula for volume of a sphere, I would find the volume of a sphere with earth's radius (call it a) and then the volume of a sphere with the admosphere's radius (call it b). b-a=atmosphere volume

2 degrees throughout the atlantic? A degree a month? Do you have ANY idea how completely impossible that is?

It takes the *sun* months to warm the atlantic to summer temps, you think you can cool the waters faster than the sun can warm them? Righty-o.
36. hurricanechaser
7:02 PM GMT on February 10, 2006
Can anyone except me see how Bob keeps the attacks going...

I ask those of you who did email me with your support...all 40 of you to please show Bob the truth if you feel comfortable doing so.

Ity sems I get emails supportig my views but they are afraid (rightfully so) to support me in public because of those like BOB.

Who are you to talk about keeping me in line... think you could do that in person?

My last post was very concilitory and apologetic, but I get this in response...

Posted By: weatherguy03 at 7:02 PM GMT on February 10, 2006.

"Ok I will stop for now. But if you get out of line again, I will right here to remind you. Oh and if you can e-mail me the list of 40 people I would appreciate it. Have a good day."
34. hurricanechaser
6:58 PM GMT on February 10, 2006
Dr. Masters,

I still believe it was wrong for you to post in your blogs information that characterizes someone in a negative manner when He himself adamantly denies it and you personally have no knowledge of the veracity of those claims about Mr. Deutsch.

That being said, I want to sincerely apologize for allowing the stress of my current living circumstances to cause me to make a likwise personal attack on you in response. Plain and simple, I was wrong in doing so and could've address that central premise without being so aggressive.


33. weatherguy03
7:00 PM GMT on February 10, 2006
Ok I will stop for now. But if you get out of line again, I will right here to remind you. Oh and if you can e-mail me the list of 40 people I would appreciate it. Have a good day.
Member Since: Posts: Comments:
32. sayhuh
6:57 PM GMT on February 10, 2006
For what its worth, based on this spirited conversation, I have decided its worthwhile to leave the ranks of quiet observation to become more active in this forum. When discussing items such as global warming, I believe there are enough facts that can equally be used to support either argument, but not enough in totality that can clearly prove either side. That being said, I truly appreciate the passion that this community shares, and myself - have been able to take into account personal views as part of an overall assessments. I do understand how political views become intertwined with this specific discussion as the expressed causes of global warming are directly related at its root to corporate/financial gains/losses. I feel environmental impact is secondary in the view of politics.

I felt compelled to atleast validate that opinions without passion seems rather void, and for a topic such as this, I am not sure any true answer or conclusion can be met.

I will continue to read this discussion, as well as that of more specific weather event analysis [which is what really drew me to this blog initally], and slip back into the observation deck - letting the players play on.
31. hurricanechaser
6:54 PM GMT on February 10, 2006
Hey Bob,

That is your opinion! I mostly get negative attention...hmmm..thatis why I got about 40 people writing me last night to PLEASE keep posting my Weather 101 series.

I apologize for critisizing your forecasting ability but you know you started on me a couple of months about global warming and calling me a fake.

Can you have the same humility and drop the personal back and forth comments that benefits neither of us?

I agree with you Colby and wil do my part from this point forward.:)

30. weatherguy03
6:55 PM GMT on February 10, 2006
Hey Colby, who asked you anyway. I am not talking to you. I dont talk to children anyway..LOL..
Member Since: Posts: Comments:
29. ForecasterColby
6:53 PM GMT on February 10, 2006
Bah, sorry about the scrolling. If admins can edit the posts, perhaps you could throw in a newline there?
28. ForecasterColby
6:51 PM GMT on February 10, 2006
hurricanechaser, weatherguy03, drop it! If one of you stops posting, the other will get bored after a while. Sheesh...can we please graduate 1st grade here?
27. ForecasterColby
6:48 PM GMT on February 10, 2006
Cyclone, someone with your firm grasp of physics (*giggle*) should know that all you're doing is moving heat down. Consider - you have, what, 100 miles of air above your head? Anyone know the formula for volume of a sphere? Because the deepest spot in any ocean is 6 miles deep. If you cool a tiny, tiny area (comparatively) like the Gulf Stream, you might lower air temps by .00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001F.

Viewing: 77 - 27

Page: 1 | 2 | 3 | 4 | 5Blog Index

Top of Page

Dr. Jeff Masters' WunderBlog


Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

JeffMasters's Recent Photos

Cedars Plastered by Snow
Snowstorm over Dunham Lake
Beech tree fall color in the U.P.
Altocumulus clouds over Pictured Rocks National Lakeshore beaver pond