RealClimate

Climate science from climate scientists...

You are here: Home / Archives for Gavin

about Gavin Schmidt

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

Taking Cosmic Rays for a spin

by

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….

[Read more…] about Taking Cosmic Rays for a spin

Attribution of 20th Century climate change to CO2

by

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.

[Read more…] about Attribution of 20th Century climate change to CO2

Carl Wunsch, The Economist and the Gulf Stream

by

Carl Wunsch usually has very interesting things to say about the climate system, and although his arguments don’t necessarily win everyone completely over, they often generate an improvement in the level of scientific discussion. In this week’s Economist, he has a letter printed concerning the mis-definition of the ‘Gulf Stream’ concept in the magazine’s climate change survey a couple of weeks ago. This is essentially a reprint of his letter to Nature that was published in 2004, which stated correctly that the Gulf Stream is basically a wind driven phenomenon and will not stop or reverse while the wind still blows and the Earth still turns. [Read more…] about Carl Wunsch, The Economist and the Gulf Stream

Sachs’ WSJ Challenge

by

Jeffery Sachs of the Columbia Earth Institute has an excellent commentary in Scientific American this month on the disconnect between the Wall Street Journal editorial board and their own reporters (and the rest of the world) when it comes to climate change. He challenges them to truly follow their interest in an “open-minded search for scientific knowledge” by meeting with the “world’s leading climate scientists and to include in that meeting any climate-skeptic scientists that that the Journal editorial board would like to invite”.

RealClimate heartily endorses such an approach and, while we leave it to others to judge who the ‘world leading’ authorities are, we’d certaintly be willing to chip in if asked. To those who would decry this as a waste of time, we would point to The Economist who recently produced a very sensible special on global warming and proposed a number of economically viable ways to tackle it, despite having been reflexively denialist not that many years ago. If the Economist can rise to the challenge, maybe there is hope for the Wall Street Journal….

Weekly Round-up

by

A few scattered pieces that may be of interest:

The increasingly-odd behaviour of the American Association of Petroleum Geologists – who recently awarded Michael Crichton a journalism award (because his work apparently has the ‘ring of truth‘ as opposed to actually being true), aroused the ire of American Quaternary Association in a commentary in EOS.

Reason Magazine has a Roundtable discussing responses to global warming from their particular perspective. The second essay (by D. Boudreaux) has the remarkable subtitle “Why ignoring climate change isn’t a sign of scientific illiteracy or of ideologically induced stupidity”. His point appears to be that the science of climate change doesn’t specifically imply any particular actions in response (which is true – what action to take, if any, is a political, ethical and economic decision). However his conclusion that ignoring climate change is sensible postition to take is indeed pretty dim. Ignorance is never the answer.

And on a lighter note, the Union of Concerned Scientists has a cartoon competition.

Chinese whispers in Australia

by

We decided months ago that we would not comment on leaks of the draft of the upcoming IPCC report (due Feb 2007) but we are prepared to correct obvious errors. The ongoing revisions of the text and the numerous drafts make any such commentary, let alone conclusions drawn from it, pretty pointless. This is even more true when the leaks are obviously confused about a central point. The principle error in the latest ‘exclusive’ is that the writer confuses a tightening of the estimate of climate sensitivity to 2xCO2 (as discussed here) with projections of climate change in 2100. These projections obviously depend on the uncertainties in the scenarios of future technology, economic progress and population (etc.) plus uncertainties in feedbacks related to the carbon or methane cycles. Unfortunately these have not been reduced since the last assessment report (and in some cases have actually increased).

That occasional stories will come out that get basic things wrong is unfortunate but not surprising. What is more troubling is that they subsequently get picked up by Reuters and UPI, and republished in places (such as Scientific American, though in their defence, it is simply a posting of the wire report) where the editors should know better. Worse still, the wire service stories are too brief to make the source of the error obvious, and thus the error gets propagated in an ever more confused state. As usual the blogsphere is playing a key role in amplifying and further muddying the story. The advantage of blogs is that errors can be corrected quickly, and the comments on Prometheus for instance, quickly revealed the confusion and the potential agenda of the original story.

There will be plenty of time to discuss the new IPCC report when it comes out and where everyone can read for themselves what has and what hasn’t changed since 2001. Until then, we would counsel against journalists and editors jumping at supposed ‘exclusives’ and – more dangerously – going ahead with them without even a basic sanity check of the details.

Nature’s press advisories

by

Articles in Nature (or Science) are embargoed for the media until the day of publication. A week before publication, Nature sends out a press advisory describing the week’s upcoming papers that is separate from any press releases that the authors or their institutions might put out. Journalists read these, and if interested, spend the time before the actual publication talking to sources and doing background so that they have (hopefully) well-thought out stories ready to go when the embargo lifts. The resulting media splash for the most interesting papers is usually good for the magazine and the authors. But not always.

Last week, the press advisory for one paper gave a slightly misleading account of one apsect of the work described in the article. Normally this would probably not get much attention, but the paper in question dealt with the highly emotional and politicized topic of stem cell research. I don’t want to get into the specifics of this paper (comments on that should be directed elsewhere) but the New York Times reported on the clarification that Nature subsequently put out and noted that the principal author Robert Lanza, had neither seen nor approved the text of the press advisory.

This might seem strange, but this is actually the normal state of affairs. Nature‘s editors write the advisories, which only go out to journalists and are not in general ever seen by the public. Often though, these short blurbs set the tone for the subsequent media attention but, if there is a problem, it can lead to a very widespread mis-communication. Colleagues of mine have been in the odd position of having to ask the journalists to read out the release concerning their own work!

We have previously discussed the problems of getting the press release just right when dealing with articles on potentially controversial science topics, and we strongly urged scientists to be more aware of how press releases are crafted and the message they send. This is obviously very difficult to do if the scientists are not involved in the process.

Coincidentally, I recently had a casual conversation with one of the Nature editors concerning this exact issue (prior to last week’s kerfuffle) and learned that the magazine was thinking about making the advisories public at the time of publication. This would definitely be a step forward for openness. I would go further and also suggest that the principal authors be given a chance to comment on the advisories before they go out. Getting things wrong – even subtly – in contentious fields doesn’t help anyone and the slight extra effort to try and prevent mis-communication is well worth it.

In a similar vein, I have found that journalists who take the time to check back with scientists on their quotes or explanations of the science often catch ambiguities or errors at an early stage and this should be encouraged as much as possible.

At a time when science and science reporting is under pressure from many quarters, journals, press officers, editors and authors need to work more closely together on ensuring that science is reported accurately and effectively.

New public opinion poll on global warming

by

There is a new Zogby poll on public attitudes in the US towards global warming and the potential connection between severe weather events and climate change.

Unsurprisingly to us (but maybe not to others), most of the US public feel that global warming is happening (around 70%), and roughly the same amount of people report being more or much more convinced of this over the last two years.

More interestingly, the pollsters asked whether people believed that global warming was having an effect on intense hurricanes, droughts, heat waves and the like. Again, roughly 70% of people thought that global warming was having either some effect or a major effect on these weather extremes (note that the question was not phrased to ask whether any specific event was thought likely to have been caused by global warming (which was probably a good choice)).

This begs the question whether people’s experience of severe weather has convinced them that climate change is occuring. Televangelist Pat Robertson, for instance, said very recently that it was the latest heat wave that finally convinced him. I think this is likely to be true for most of the public who are not following the issue very carefully (which is most of them of course!). The most significant single event in this context was probably Katrina, regardless of how much climate change can or can’t be associated with Katrina the Hurricane (let alone Katrina the Disaster!).

I would guess that this is likely to be a very common way for public opinion to be formed across a whole number of issues. That is, when a dominant theme is very prevalent across a wide spectra of media, everyday occurrences or new information are often processed with that in mind, and given our extraordinary ability to see patterns in noisy data, we often end up associating the theme with our own experiences. Other examples surely abound in medical or political contexts.

Given that pattern, it is probably overly optimistic to expect scientists, who continually stress that single weather events can’t in general be attributed to climate change but that changes in statistics might be, to have much success in conveying these finer points to the public directly. Instead, their skills are probably best used in clarifying these points to those (e.g. journalists, policy-makers) that set the dominant themes in the first place.

Ocean heat content: latest numbers

by

Net ocean heat content changes are very closely tied to the net radiative imbalance of the planet since the ocean component of the climate system has by far the biggest heat capacity. Thus we have often made the point that diagnosing this imbalance through measurements of temperature in the ocean is a key metric in evaluating the response of the system to changes in CO2 and the other radiative forcings (see here).
In a paper I co-authored last year (Hansen et al, 2005), we compared model results with the trends over the 1993 to 2003 period and showed that they matched quite well (here). Given their importance in evaluating climate models, new reports on the ocean heat content numbers are anticipated quite closely.

Recently, a new preprint with the latest observations (2003 to 2005) has appeared (Lyman et al, hat tip to Climate Science) which shows a decrease in the ocean heat content over those two years, decreasing the magnitude of the long-term trend that had been shown from 1993 to 2003 in previous work (Willis et al, 2004) – from 0.6 W/m2 to about 0.33 W/m2. This has generated a lot of commentary in some circles, but in many cases the full context has not been appreciated.
[Read more…] about Ocean heat content: latest numbers

The missing repertoire

by

There was a small flurry of activity last week when the report “Warm words: How are we telling the climate story and how can we tell it better?” was released by the IPPR (a UK based left-leaning think tank). Most of the attention was focussed on their attention-seeking description of the more breathless media depictions of climate change as ‘climate porn’. However, the report was actually more interesting than just that, but possibly in ways that the authors didn’t intend.

[Read more…] about The missing repertoire