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Teaching Climate Science

Posted on 22 March 2011 by Daniel Bailey


The National Center for Atmospheric Research (NCAR) is a federally funded research and development center devoted to service, research and education in the atmospheric and related sciences. NCAR’s mission is to understand the behavior of the atmosphere and related physical, biological and social systems; to support, enhance and extend the capabilities of the university community and the broader scientific community – nationally and internationally; and to foster transfer of knowledge and technology for the betterment of life on Earth. The National Science Foundation is NCAR's primary sponsor, with significant additional support provided by other U.S. government agencies, other national governments and the private sector.


Dr. Kevin Trenberth, Senior Scientist, CAS Section Head

The Climate Analysis Section (CAS) is a research section within Climate & Global Dynamics Division (CGD) of the NCAR Earth System Laboratory (NESL).

Dr. Kevin Trenberth is Head of the Climate Analysis Section at the National Center for Atmospheric Research (NCAR) in Boulder, CO.

Dr. Trenberth is famous for his research into climate science.  As part of his work, he prepares presentations and videos to help educate the public and policymakers. The feature of this post is Dr. Trenberth's Invited Keynote Address, "The Earth's Climate System: Variability and Change," presented at the Symposium on Climate Change Effects on Fish and Fisheries, Sendai, Japan, 26-29 April 2009.

Over the course of 23 minutes and 40 seconds, Dr. Trenberth covers a comprehensive range of climate topics including the Greenhouse Effect, Earth's energy flows and budget, the roles of each component (air, ocean, land and ice) of the biospher of the Earth, temperature & Co2 variations and sea level rise, followed by discussions of changes in humidity and how that effects weather around the globe.

Some of Dr. Trenberth's most powerful statements made in the video are:

  • "The recent 2003 European heat wave could only have ocurred through a combination of natural variability and global warming."
  • "Global Warming doesn't mean relentless warming year after year after year."

It's a must-watch video, one of the most educational and accessible I've seen. Watch it and then tell everyone you know to see it.

Here are a few screenshots to whet your appetite and draw your interest:


Figure 1. The warming of the globe is unequivocal


Fig 2. Warming Attribution       Fig3. Greenhouse Effect           Fig 4. Water Vapor

Energy Flows

Fig 5. Earth's Energy Flows

One of the things that struck me while researching this article was the observation that Dr. Trenberth had made about his widely misquoted comment (discussed here and here):

"The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't."

Here's Dr. Trenberth's thoughts on the matter:

"It is quite clear from the paper that I was not questioning the link between anthropogenic greenhouse gas emissions and warming, or even suggesting that recent temperatures are unusual in the context of short-term natural variability."

Further Reading

Dr. Trenberth's CV and Publication Record

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Comments 1 to 23:

  1. Fig 5 certainly indicates how just a small change in cloud cover could have a big effect on the heat balance. I guess we only have to stand in the sun as a cloud comes over to appreciate just how significant this is.
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  2. Figure 2 is absolute garbage- numbers coming off totally varying bases with no scientific credibility. Its maths only not science. You can do anything with maths.
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  3. cloa513 - please substantiate your claims if you want to make sense. Maths is the handmaiden to science, modelling known physics. You may wish to comment on Models are unreliable but I wouldnt bother unless you have some substance to your claim.
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  4. Energy flows are real. Energy is energy. Temperature is not temperature under different conditions. They should have error margins because of calculations, measurement error etc. I bet those errors margins are large and what is the natural baseline to compare this numbers with. Its impossible to produce a baseline that doesn't even larger error margins as the data was considerably less and less accurate. Instead they rely on models which can't produce real testable results using direct measurements.
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  5. cloa513 - the pattern of your comments strongly suggests that you are uncritically assuming something you have read on a pseudo-skeptic source is true. How about picking up the claim you think most convincing, find the Argument from the top bar that matches it, and then taking it from there. But for goodness sake, read the rebuttal, read the linked papers and then tell us why think it is still wrong. (Preferably with data and peer-reviewed literature to support your claim).
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  6. The first two commenters have obviously (judging by their timestamps) not even bothered watching the educational video that is the subject and focal point of this post. Pity. If they had bothered to take that valuable time then perhaps they might have dwelt a bit longer on their learnings before posting as they did. "Invest the copper coins of your pocket in your mind and your mind will line your pockets with gold..." The Yooper
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  7. cloa513 - look closer at the figure. The shaded portions are the error bars. Your comments about temperature make no sense. Please explain (but preferably in the right place on this site). The natural baseline is sum of known natural forcing (solar, volcanic aerosols etc). This is explained in considerable detail in IPCC WG1 and in the papers it links to. As to models not being able to produce testable results, well have a look at this In sum, you are believing things about climate science that are not true.
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  8. Without maths you can claim (as a Perth resident did) that sea level rise is due to increasing obesity of Australians! As others have pointed out, you are misunderstanding "global mean temperature" and thus challenging a straw man. Please go to temperatures are unreliable as suggested. The GISSTemp site has a very extensive list of its published methods and papers. Start here for the methodology. More is explained in IPCC WG1. It appears to me you havent read it given the claims you are making. Care to tell us what your source for these claims are?
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  9. Great presentation (except for the Comic Sans font) I like Dr Trenberth's explanation of the 2003 European heat wave.
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  10. yocta - there are worse things than Comic Sans... (some of the PPT slides I've seen at work just make you want to cry!) I can't make up my mind whether cloa513 is a robo-troll, or someone who genuinely doesn't understand the basics of climate science. If the latter, then he/she would *definitely* benefit by watching the video, then coming back here to ask (meaningful) questions.
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  11. Bern, your comment about being unable to distinguish between a robo-troll and a real person is amusing :-)
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  12. Figure 2 is not garbage. It's just illustrative of computer scientist's world. Simulate something. Change a parameter. You build another world. No idea if it is real or not - and no way to check it. Don't mind.
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    Moderator Response: Your comment belongs on the thread "Models are unreliable."
  13. OR that was an illustration of denialism: Claim something without even knowing what your talking about. Don't check reality, even if it's shown to you. Repeat ad nauseam.
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  14. This is an excellent video, Kevin presents and explains the evidence well.
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  15. Gilles @ 12... Can you please explain what the motivation would be for a scientist to produce work that has no relationship or bearing on the world around him/her? No scientist is ever going to advance their career by producing work that has absolutely no relationship to the real world. If you spend any time at all listening to these guys or reading their research you find they all say that models are not perfect. They are continually improving the models. But the models create a strong approximation of the climate system. And they have DO have many ways to test how reliable the models are.
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  16. Gilles - fig 2 is normal science. You create a model for reality, you test it by calculating results and comparing to reality. What method would YOU propose for looking at how much temperature would change based on natural forcing only? Create another identical earth - or use your best computer model for earth? This normal science in every field I am used to.
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  17. scaddenp : I'm not saying that's unusual science. But even in normal science, computer simulations are never taken as evidence that things are real, until they have been carefully validated. I see here no real validation that things would have happened like that without anthropogenic forcing. May be it's impossible - sorry for that.
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  18. So when I am making an aircraft, and my models show undesirable behaviour, then I have make the plane to validate it? Of course not, thats why we have models. What you have to do is validate the model makes a reasonable job of predicting the behaviour of the planes we do make. That is the validation that goes into climate modelling. With confidence from that, then it is perfectly reasonable to evaluate other inputs. Suppose the modelling had showed that natural forcings gave a climate that was in the error bounds of natural+forcing? Then it would have been possible to say that while there might some grounds for concern from nature of GH theory, there was no conclusive evidence that we had anything to worry about. However, that is not what the models show and it is perfectly valid to show that.
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  19. One basic way to test a model is to take the first half of the data (over time) to generate the model, then see if it predicts the second half of the data. Can anyone show me a model that predicts the lack of warming over the past 10 years or so? I know that people want to say it's a short term blip - we need to be talking 30 years minimum. What about a model that would have predicted the steady temperature 1940 - 1980, or the increase from 1910 - 1940. I also know about the theories of volcanoes etc to explain these, but there's too much "the model would have worked except for....." I find the speculation that we're coming into a cooling period just as convincing. I know this is getting off the track for this thread, and I apologise.
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    Moderator Response: [Dikran Marsupial] The "lack of warming" over the last ten years is likely to be due to internal variability - it isn't climate. The models do predict that there will be occasional periods of apparent cooling even during long term warming trend, but the can't predict when they will happen as they are chaotic. See the excellent paper by Easterling and Wehner. It is unreasonable to complain that the models are not able to predict something the modellers would not claim they could model. As for the 1940-1980 levelling and the 1910-1940 warming, the models actually do predict them - see the IPCC reports. If you want to discuss this further, please do so on a more appropriate thread.
  20. @ rhjames (19) "Can anyone show me a model that predicts the lack of warming over the past 10 years or so? I know that people want to say it's a short term blip - we need to be talking 30 years minimum." When one filters out the cyclical noise and the effects of volcanoes on the system, it is possible to see a significant temperature vector in the data in temperature datasets, even in periods shorter than 30 years: But it takes someone skilled in time series analysis to do the job right when dealing with extremely short time series, such as the significant warming of the globe since 2000, as shown above. That's why most climatologists, being very conservative with what they say, prefer to use as much data as they can get (generally 30 years or more) to make their evaluations. Otherwise what you're asking is impossible: to prove or disprove the non-existence of something. Hope this helps, The Yooper
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  21. rhjames, you might want to look at the global cooling bet for a very particular set of model runs that predicted global cooling. What Keenlyside et al 08 were attempting to do was interesting but as the article discusses, the model arent there yet. (And real data isnt backing the prediction). At the article on Realclimate -what the ipcc models really say you will see a graph of many individual model runs. Each is a possible future. It shows many possible short term (10-20 year) possibilities with no way to say one is more likely than another. However, the long term trend for all these possibilities is unequivocal.
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  22. "I see here no real validation that things would have happened like that without anthropogenic forcing." Gilles - I have a great idea for validation. Why dont we stop producing any anthropomorphic forcings and see climate settles to predicted natural forcings?
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  23. #17, Gilles: "computer simulations are never taken as evidence that things are real, ... no real validation that things would have happened like that without anthropogenic forcing." Clearly you do not understand Figure 2. The validation you claim to seek is there (its called matching the models to history). Without anthropogenic forcing, there is no match. But you've said that you're not really here to discuss such scientific goings-on, so you've rendered your own opinions on this question moot.
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