In the early 1990’s, in defiance of IPCC projections, the methane concentration in the atmosphere abruptly stopped rising, and has remained nearly constant since then. Methane is a crouching tiger in the carbon cycle, with potentially enough available as hydrates and from peats to really clobber the Earth’s heat budget. The big question is, will atmospheric methane start rising again? [Read more…] about Rasslin’ swamp gas
Climate Science
Global cooling, again
The ice age is coming, the sun’s zooming in / Engines stop running and the wheat is growing thin /A nuclear error, but I have no fear /’Cause London is drowning, and I live by the river (chorus from London’s Calling, by Strummer/Jones, 1979).
New Google search function
It can be easy to find climate science information on the web, but that information ranges from the excellent to the atrocious – and it can often be hard to tell them apart without some prior expertise. Wouldn’t it be great if someone could vet the information beforehand so that you had some confidence that it wasn’t completely bogus? Well, you need wait no longer!
Some of you may have already noticed that we have updated our search facility to use a new service from Google Co-op which is being launched today. The idea is that the search is restricted to domains and pages that have passed some kind of quality control. RealClimate is one of the demo sites of the new technology and we have started off with a selection of sites (IPCC, goverment labs, research institutes etc. – as well as RealClimate itself of course!) that we know provide quality information about climate science. As we get used to this service, we will be adding sites and pages that we feel are up to the mark. Suggestions for sites that we might not yet have found or have overlooked, will of course be welcome.
Eventually, we hope to have a service that could be an essential resource for the interested public, journalists, and possibly even scientists, that would give a higher quality level of information than is possible now. Let us know if this ends up being useful to you and if you have any suggestions for improving the service.
Taking Cosmic Rays for a spin
) (
) 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….
How not to attribute climate change
In an earlier post, we discussed a review article by Frohlich et al. on solar activity and its relationship with our climate. We thought that paper was quite sound. This September saw a new article in the Geophysical Research Letters with the title «Phenomenological solar signature in 400 years of reconstructed Northern Hemisphere temperature record» by Scafetta & West (henceforth referred to as SW). This article has now been cited by US Senator James Inhofe in a senate hearing that took place on 25 September 2006 . SW find that solar forcing accounts for ~50% of 20C warming, but this conclusion relies on some rather primitive correlations and is sensitive to assumptions (see recent post by Gavin on attribution). We said before that peer review is a necessary but not sufficient condition. So what wrong with it…?
Con Allègre, ma non troppo
Guest Commentary by Georg Hoffmann (LSCE)
Climate change denial is not necessarily a speciality of Washington DC think tanks – sometimes it can also be found in old Europe. Right now there is a little media storm passing by in France evoked by an article from Claude Allègre in L’Express. Who is Claude Allègre? He is one of the most decorated french geophysicists specializing in geochemistry and the use of paleomagnetism. Being a longtime friend of the former prime minister, Lionel Jospin, he even became Minister of Education and Research in the former Socialist government. He still plays an active role within the Socialist party and though he has never published anything directly related to anthropogenic climate change, one would assume that he has some understanding of the scientific matter. But this assumption would be wrong.
In the French weekly journal l’Express he exposed his “sceptical” views in an article entitled “The snows of Kilimanjaro”. In the short editorial, he somehow became lost when following Ernest Hemingway to East Africa. Allègre mentions two scientific examples to demonstrate that there is something fundamentally wrong in the IPCC statements on the reality of climate change. First, he commented on the disappearing glaciers of the Kilimanjaro, sometimes treated as the “Panda” of anthropogenic climate change. Citing a “Nature” study (which was in fact published in Science) by Pierre Sepulchre and colleagues from my laboratory, he claimed that this modelling study demonstrated that Kilimanjaro’s glaciers are controlled by tectonic activity. In fact, the article describes the impact of tectonics of the East African Highlands on Indian ocean moisture transport —- on a time scale of millions of years! This confuses glacier variability over the last ~100 years with rainfall trends extending back to the time of the early hominids (such as Lucy).
In fact, there are good reasons to believe that the situation on the Kilimanjaro is a bit more complicated than a simple “atmosphere gets warmer/ glaciers are melting” equation (for instance, see this previous post on tropical glacier retreat). Furthermore, the real link to climate change does not come from the retreat of one single tropical glacier, but from the fact that, to my knowledge, all studied tropical glaciers have retreated over the 20th century, and the retreat rates have generally increased in recent decades.
Allègre’s misunderstanding was immediately followed by another one. Citing a recent study on relatively stable Antarctic snowfall over the last 30 years (Monaghan et al, 2006, discussed here) , he highlighted what he thought was a clear contradiction to future climate simulations of global circulation models (melting of the Antarctic ice sheet). However, that’s not what they predict. All models predict a comparably stable Antarctic ice sheet for the 21th century in which comparably moderate temperature changes in Antarctica are compensated by slight increase in snowfall. The Monaghan et al study does not contradict these model scenarios.
The French climate research community was of course not very pleased about this short sequence of misrepresentations and personal attacks (“les Cassandres”) and corrected Allègre in an open letter published here on the website of the Institute Pierre Simon Laplace (which includes links to the ongoing back and forth, for those that speak French).
Curiously enough, twenty years ago Allègre wrote in “Clés pour la géologie”, (éd. Belin/France Culture):
“En brûlant des combustibles fossiles, l’homme a augmenté le taux de gaz carbonique dans l’atmosphère, ce qui fait, par exemple, que depuis un siècle la température moyenne du globe a augmenté d’un demi-degré.”
(Translation)
“By burning fossil fuels man enhanced the concentration of carbon dioxide in the atmosphere which has raised the global mean temperature by half a degree in the last century”.
But at that time he used this argument against the anti-nuclear energy movement. It might be that there is simply a bit too much politics in Allègre’s life…
Attribution of 20th Century climate change to CO2
) () 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
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
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….
The trouble with sunspots
by Gavin Schmidt and Michael Mann
Solar forcing of climate is a subject that gets far more attention than any new observations or improved understanding would warrant. Two new articles appearing today attest to that. One is occasionally tempted to agree with Oscar Wilde when he said:
Why does not science, instead of troubling itself about sunspots, which nobody ever saw, or, if they did, ought not to speak about; why does not science busy itself with drainage and sanitary engineering?
Except in this case it’s Nature rather than Science who are troubling themselves…
A new review paper by Foukal et al does a reasonable job summarising the mainstream opinion on the issue. In particular, they outline quite clearly why some ideas related to long term solar variability (such as solar disk radius changes, or the difference between cycling and non-cycling stars) have recently fallen out of favor. Indeed, they assert that there is little evidence for any solar variability in irradiance that is not related to the shielding/enhancements of sunspots and faculae – which implies only a modest decrease in solar flux at the Maunder Minimum for instance. We could quibble with their use of paleo-reconstructions, their climate modeling approach, and the rather cursory treatment of the substantial body of work relating to amplyfying mechanisms due to UV/ozone links, but we’ve gone over this ground before and we refer readers to those earlier discussions.
Slightly more novel is the description in the News section of a new experiment at CERN that is attempting to test the cosmic-ray/cloud hypothesis by building a large cloud chamber mimicing the atmosphere and firing high energy particles at it. There’s nothing intrinsically wrong with the idea, but given the $11 million to spend on climate change research, we would have tended to favour projects that, unlike this one, have at least some empirical support within the observations….