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about Gavin Schmidt

Gavin Schmidt is a climate modeler, working for NASA and with Columbia University.

AGU Hangover

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It turns out that there were almost 14,000 attendees at AGU last week, which apparently makes it the largest Earth Science meeting ever held. To be sure, not all of that is climate related – there was lots of seismology, planetary and more theoretical/small-scale stuff, but a lot of it was. At most times there were at least half a dozen sessions that I would have been interested to attend – and they were often discussing overlapping themes.

It used to be that one could go to a meeting like this and get a wide overview of the work being done much more efficiently (and speedily) than reading the journals. However, that is clearly no longer true. And of course, we can’t keep up with all the relevant journal articies in the wider field either, and so how do scientists manage?
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Fall AGU

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The Fall AGU meeting in San Francisco is always an exhilarating/exhausting (take your pick) fixture of the Earth Science calendar. This year will be no different, and since about half of us will be there, RealClimate will probably be a little quiet next week. Hopefully, we should be able to report on any highlights when we get back.

N.B. If any readers will be attending and want to say hi, I will be giving a talk on ‘Science blogging: RealClimate.org and the Global Warming debate‘ on Friday (PA53A, 13:40, MCS 309).

Update: AGU went well – lot’s of good stuff. The actual RealClimate presentation is available here – it’s pretty basic though (only 15 minutes worth)).

Inhofe’s last stand

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Part of me felt a little nostalgic yesterday watching the last Senate hearing on climate change that will be chaired by Sen. James Inhofe. It all felt very familiar and comforting in some strange way. There was the well-spoken ‘expert’ flown in from Australia (no-one available a little closer to home?), the media ‘expert’ from the think tank (plenty of those about) and a rather out-of-place geologist. There were the same talking points (CO2 leads the warming during the ice ages! the Medieval Warm Period was warm! it’s all a hoax!*) that are always brought up. These easy certainties and predictable responses are so well worn that they feel like a pair of old slippers.
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Historical climatology in Greenland

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Gavin Schmidt & Michael Mann

Extending the instrumental record of climate beyond the late 19th Century when many of the national weather centers were first started is an important, difficult and undervalued task. It often is more akin to historical detective work than to climatology and can involve long searches in dusty archives, the ability to read archaic scripts and handwriting, and even Latin translations (for instance, when going through the archives of the Paris Observatory) (sounds like a recent bestseller, only less lucrative, no?).
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The sky IS falling

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Translations: (Français)


A timely perspective article in Science this week addresses the issues of upper atmosphere change. ‘Upper’ atmosphere here is the stratosphere up to the ionosphere (~20 to 300 km). Laštovička et al point out that cooling trends are exactly as predicted by increasing greenhouse gas trends, and that the increase in density that this implies is causing various ionspheric layers to ‘fall’. This was highlighted a few years back by Jarvis et al (1998) and in New Scientist in 1999 (and I apologise for stealing their headline!).

The changes in the figure are related to the cooling seen in the lower stratospheric MSU-4 records (UAH or RSS), but the changes there (~ 15-20 km) are predominantly due to ozone depletion. The higher up one goes, the more important the CO2 related cooling is. It’s interesting to note that significant solar forcing would have exactly the opposite effect (it would cause a warming) – yet another reason to doubt that solar forcing is a significant factor in recent decades.

Update: The best explanation for the cooling trends can be found on ESPERE (alternative site), in particular, figure 3 (alt. version).

English vineyards again….

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Readers may recall a thorough examination of the history of English wine here a few months ago – chiefly because the subject tends to come up as a contrarian climate talking point every now and again. The bottom line from that post was that the English wine industry is currently thriving and has a geographical extent and quality levels that are unprecedented in recorded history. So whether vineyards are a good proxy for climate or not, you certainly can’t use the supposed lack of present day English vineyards in any serious discussion about climate….

So along comes this quote today (promoting Fred Singer’s latest turnaround) (my emphasis):

“The Romans wrote about growing wine grapes in Britain in the first century,” says Avery, “and then it got too cold during the Dark Ages. Ancient tax records show the Britons grew their own wine grapes in the 11th century, during the Medieval Warming, and then it got too cold during the Little Ice Age. It isn’t yet warm enough for wine grapes in today’s Britain. Wine grapes are among the most accurate and sensitive indicators of temperature and they are telling us about a cycle. They also indicate that today’s warming is not unprecedented.”

Hmmm…. so where did that bottle of Chapel Down in my fridge come from? (thanks Dad!) Or the winners of the ‘Best Sparkling Wine’ for the last two years at the International Wine and Spirit Competition? This is of course a trivial point, but it demonstrates (once again) that our contrarian friends don’t even have a semblence of a desire to get it right. The lure of a talking point clearly trumps the desire for accuracy.

In vino veritas (though not in this case).

Update: We had the Chapel Down Flint Dry last night. Fruity, hints of apple and pear and one of better whites I’ve had in a while. Highly recommended!

Cuckoo Science

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Translations: (Français)

Sometimes on Realclimate we discuss important scientific uncertainties, and sometimes we try and clarify some subtle point or context, but at other times, we have a little fun in pointing out some of the absurdities that occasionally pass for serious ‘science’ on the web and in the media. These pieces look scientific to the layperson (they have equations! references to 19th Century physicists!), but like cuckoo eggs in a nest, they are only designed to look real enough to fool onlookers and crowd out the real science. A cursory glance from anyone knowledgeable is usually enough to see that concepts are being mangled, logic is being thrown to the winds, and completely unjustified conclusions are being drawn – but the tricks being used are sometimes a little subtle.

Two pieces that have recently drawn some attention fit this mold exactly. One by Christopher Monckton (a viscount, no less, with obviously too much time on his hands) which comes complete with supplementary ‘calculations’ using his own ‘M’ model of climate, and one on JunkScience.com (‘What Watt is what’). Junk Science is a front end for Steve Milloy, long time tobacco, drug and oil industry lobbyist, and who has been a reliable source for these ‘cuckoo science’ pieces for years. Curiously enough, both pieces use some of the same sleight-of-hand to fool the unwary (coincidence?).

But never fear, RealClimate is here! [Read more…] about Cuckoo Science

Ocean Circulation: New evidence (Yes), slowdown (No)

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Sometimes journalists are so focused on a particular story that they ‘hear what they want to hear and disregard the rest’. There was a perfect example of this last week in the Guardian reporting from the RAPID Climate Change conference in Birmingham (UK) which I was attending. The conference, whose theme was observations, modelling and paleo-climate related to the Thermohaline and Meridional overturning circulation (MOC) in the North Atlantic, could have been expected to attract media attention (particularly in the Europe) and indeed it did. However, the Guardian story, which started “Scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate” was in complete opposition to the actual evidence presented and I wasn’t the only person to notice. How could the reporting be so wrong?
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Taking Cosmic Rays for a spin

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Translations: (Español)

In 1859, John Tyndall’s laboratory experiments showed that water vapour and carbon dioxide absorb infra-red radiation and that they could therefore affect the climate of the Earth. As soon as his paper was published (1861) in the Proceedings of the Royal Society, he put out a press release for the London newspapers explaining that this result implied that all past climate changes were now understood and all future climate changes could be predicted simply from a knowledge of the concentrations of these ‘greenhouse’ gases…

Fast forward to 2006: Svensmark and colleagues’ laboratory experiments show that highly ionizing radiation can create ultra-small aerosol particles. As soon as the paper is published in the Proceedings of the Royal Society, they put out a press release for the world’s newspapers explaining that this result implied that all past climate changes were now understood and all future climate changes could be predicted simply from a knowledge of the intensity of these ‘cosmic rays’….

History repeating itself? Well, not exactly. Tyndall actually restricted himself to describing his experiments and simply linking it to the work of Fourier a few decades earlier. It took more than another century before the credible quantitative estimates of these effects and their influence on past and possibly future climate were made, along with good enough observations of the gases to know that they have (and continue) to change significantly. However, Svensmark and colleagues, not wanting to wait for the credible quantitative results to come in, instead short circuited all of that tedious follow-up work, scaling up to realistic conditions, theoretical and modelling studies demonstrating that their effect was indeed viable, and simply declared in their press materials that the team had ‘discovered that cosmic rays play a big part in the everyday weather’ and ‘brings to a climax a scientific quest that has lasted two centuries’. Nobel prizes all round then.

Alas! if only it were that simple….

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Attribution of 20th Century climate change to CO2

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Translations: (Slovenčina)

The discussion of climate change in public (on blogs, in op-eds etc.) is often completely at odds to the discussion in the scientific community (in papers, at conferences, workshops etc.). In public discussions there is often an emphasis on seemingly simple questions (e.g. the percentage of the current greenhouse effect associated with water vapour) that, at first sight, appear to have profound importance to the question of human effects on climate change. In the scientific community however, discussions about these ‘simple’ questions are often not, and have subtleties that rarely get publicly addressed.

One such question is the percentage of 20th Century warming that can be attributed to CO2 increases. This appears straightforward, but it might be rather surprising to readers that this has neither an obvious definition, nor a precise answer. I will therefore try to explain why.

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