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Archives for April 2006

Addendum to “A Mistake with Repercussions”

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1. What are “pseudo-proxies” and why are they useful?

Our only information from before the “instrumental period” (the period from which we have systematic measurements with thermometers, starting around 1850) comes from proxy records of climate (like tree rings, ice cores, corals, sediments, pollen etc.). Therefore it is important to know what the available kind and distribution of proxy records can tell us about quantities that we care about (like changes in the average temperature of the northern hemisphere). A typical question is: what accuracy for the northern hemisphere temperature can one expect, given the available number and spatial distribution of proxies? How much uncertainty arises from the non-climatic ‘noise’ in these records? How do the different methods for combining the proxies compare? And so on…

If there was sufficient length of good instrumental data, then we would be able to answer these questions simply by comparing measurements with proxy records. But the instrumental record is short – after all this is the prime reason why we have to rely on proxies.
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A Mistake with Repercussions

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Today, Science published an important comment pointing out that there were serious errors in a climate research article that it published in October 2004. The article concerned (Von Storch et al. 2004) was no ordinary paper: it has gone through a most unusual career. Not only did it make many newspaper headlines [New Research Questions Uniqueness of Recent Warming, Past Climate Change Questioned etc.] when it first appeared, it also was raised in the US Senate as a reason for the US not to join the global climate protection efforts. It furthermore formed a part of the basis for the highly controversial enquiry by a Congressional committee into the work of scientists, which elicited sharp protests last year by the AAAS, the National Academy, the EGU and other organisations. It now turns out that the main results of the paper were simply wrong.
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Gray and Muddy Thinking about Global Warming

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Anybody who has followed press reporting on global warming, and particularly on its effects on hurricanes, has surely encountered various contrarian pronouncements by William Gray, of Colorado State University. A meeting paper that Gray provided in advance of the 2006 27th Conference on Hurricanes and Tropical Meteorology (taking place this week in Monterey California, and covered here by CNN), provides an illuminating window into Gray’s thinking on the subject. Our discussion is not a point-by-point rebuttal of Gray’s claims; there is far more wrong with the paper than we have the patience to detail. Gray will have plenty of opportunities to hear more about the work’s shortcomings if it is ever subjected to the rigors of peer review. Here we will only highlight a few key points which illustrate the fundamental misconceptions on the physics of climate that underlie most of Gray’s pronouncements on climate change and its causes.

Gray’s paper begins with a quote from Senator Inhofe calling global warming a hoax perpetrated on the American people, and ends with a quote by a representive of the Society of Petroleum Geologists stating that Crichton’s State of Fear has "the absolute ring of truth." It is the gaping flaws in the scientific argument sandwiched between these two statements that are our major concern. [Read more…] about Gray and Muddy Thinking about Global Warming

How not to write a press release

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A recent BBC radio documentary on the possible over-selling of climate change, focussed on the link between high profile papers appearing in Nature or Science, the press releases and the subsequent press coverage. One of the examples chosen was the Stainforth et al climateprediction.net paper that reported the ranges of climate sensitivity within their super-ensemble of perturbed physics runs. While there was a lot of interesting science in this paper (the new methodology, the range of results etc.) which fully justified its appearance in Nature, we were quite critical of their basic conclusion – that climate sensitivities significantly higher than the standard range (1.5 – 4.5ºC) were plausible – because there is significant other data, predominantly from paleo-climate, that pretty much rule those high numbers out (as we discussed again recently). The press coverage of the paper mostly picked up on the very high end sensitivities (up to 11ºC) and often confused the notion of an equilibirum sensitivity with an actual prediction for 2100 and this lead to some pretty way-out headlines. I think all involved would agree that this was not a big step forward in the public understanding of science.

Why did this happen? Is it because the scientists were being ‘alarmist’, or was it more related to a certain naivety in how public relations and the media work? And more importantly, what can scientists do to help ensure that media coverage is a fair reflection of their work? [Read more…] about How not to write a press release

Kristof on the Apocalypse

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We have noted with pleasure Nicholas Kristof’s column, The Big Burp Theory of the Apocalypse (TimesSelect subscription required), which appeared in the New York Times of 18 April. This column is built around the possibility of a catastrophic methane release from marine clathrate decomposition, but at heart it is really a lament that the more conventional and better understood harms of global warming have not proved sufficient to get the attention of the White House or Congress. This column is a refreshing change from the recent spate of backlash columns by Will, Novak and Lindzen attempting to tar climate scientists with the “a****mist” epithet.

Kristof gives a generous tip of the hat to “the excellent discussion of methane hydrates by scholars at www.realclimate.org.” (Thanks, Nick.) He has clearly made good use of Dave Archer’s RealClimate article on clathrates, and it shows in the Kristof’s sound discussion of the basic science. He is very clear on why a clathrate catastrophe would be a bad thing, but equally clear about the uncertainties. The column even contains an intelligent discussion of the Paleocene-Eocene Thermal Maximum as a possible example of a clathrate catastrophe. taking care to point out that this event might not, in fact, have been caused by methane release. Quite a lot to get in a short column, while still managing to achieve a lively style that surely keeps the readers awake.

Perhaps closest to our hearts is Kristof’s cogently stated theme that uncertainty is in the nature of the science, and is no excuse for inaction — indeed should be a spur to greater action. “The White House has used scientific uncertainty as an excuse for its paralysis. But our leaders are supposed to devise policies to protect us even from threats that are difficult to assess precisely — and climate change should be considered even more menacing than a nuclear-armed Iran.” He concludes, “The best reason for action on global warming remains the basic imperative to safeguard our planet in the face of uncertainty, and our leaders are failing wretchedly in that responsibility.”

Kristof is a 2006 winner of the Pulitzer Prize for commentary. Congratulations, Nick! We hope you keep on reading RealClimate.

Global Dimming and climate models

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Guest posting from Beate Liepert (LDEO)

On April 18th PBS will air the NOVA documentary “Dimming the Sun” which stirred up lively discussions among scientists and non-scientists when originally shown by BBC in the UK (under the name ‘Global Dimming’ – see our previous posts). [The NOVA version has been thoroughly re-edited and some of the more controversial claims have apparently been excised or better put into context [and we look forward to seeing it! – Ed.].

Global dimming is the phenomena of an observed reduction (about 1-2% per decade since ~1960) of sunlight reaching the surface of the Earth caused by air pollution (aerosols – small particles) and cloud changes. Some of this solar energy is reflected back out to space and this cooling effect is believed to have counteracted part of the greenhouse gas warming. The original version of the film focused mainly on the observational recognition of global dimming, but one aspect did not receive much attention in the film – namely the oft-claimed lack of global dimming in climate models. This led some to assume that climate modelers were ignoring air pollution other than greenhouse gases emissions from fossil fuel burning. Another implication was that climate models are not capable of adequately simulating the transfer of sunlight through the atmosphere and the role of clouds, sunlight extinction of aerosols and aerosol effects on clouds etc, and therefore model projections should not be trusted. The NOVA version will address this issue more prominently by adding an interview with Jim Hansen from NASA Goddard Institute for Space Studies. Along this line, I’d like to elaborate on aerosols in climate models in more detail. [Read more…] about Global Dimming and climate models

Lindzen: point by point

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Daniel Kirk-Davidoff (U. Maryland and one-time Lindzen co-author) provided a more detailed rebuttal of Lindzen’s argument in the comments to our previous post. It deserves to be more widely seen, so here it is again.

Here’s an effort at a point by point rebuttal. I would say that the central flaw in the op-ed is a logical one: if you’re trying to stifle dissent, then you want less funding for climate research, not more. If you’re trying to stop global warming, then you want more money for carbon sequestration research, and you don’t care how much is spent on climate research. On the other hand if you just love climate research as a really interesting intellectual pursuit, that’s when you’ve got an interest in shedding doubt on the reigning view that CO2-induced climate change is a serious policy program, requiring action. Twenty-five years ago, when global warming wasn’t a big public worry, one might expect climate change researchers to hype the problem. In 2006, when public opinion mostly accepts that there’s a problem, scientists who want research money should be emphasizing uncertainty.
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Open Thread on Lindzen Op-Ed in WSJ

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We’ve received a large number of requests to respond to this piece by MIT’s Richard Lindzen that appeared as an op-ed in today’s Wall Street Journal. We’ve had lots to say before about the Wall Street Journal (e.g. here and here), and we’ve had plenty to say about Lindzen as well. Specifically, we have previously pointed out that there is no evidence whatsoever that ‘alarmism’ improves anyone’s chances of getting funded – if anything it is continued uncertainty that propels funding decisions, and secondly, the idea that there is a conspiracy against contrarian scientists is laughable. There is indeed a conspiracy against poor science, but there is no need to apologise for that! But rather than repeat ourselves once again, we thought we’d just sit back this time and allow our readers to comment…

Lessons from Venus

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by Rasmus Benestad and Ray Pierrehumbert

Venus Express will make unprecedented studies of the largely unkown phenomena taking place in the Venusian atmosphere. Credits: ESA - AOES Medialab A special report in The Observer on Sunday (April 9) titled ‘Venus – The Hot Spot’, provides a well-written account on a mission called the Venus Express. The Venus express is an European Space Agency (ESA) mission to probe the the atmosphere of Venus and address questions regarding the differences between the climates on Venus and Earth. According to the plans, the probe will enter the final orbit around Venus in May 2006, i.e. within about a month.

What relevance does a mission to Venus have for a blog like RealClimate? Primarily, Venus offers scientists the chance to see how the same basic physics used to study Earth’s climate operates under a very different set of circumstances. In one sense, Venus is rather similar to Earth: it has nearly the same mass as Earth, and while its orbit is somewhat closer to the Sun, that effect is more than made up for by the sunlight reflected from Venus’ thick cloud cover. Because of the cloud cover, the surface temperature of Venus would be a chilly -42C if were not for the greenhouse effect of its atmosphere. In reality, the surface of Venus, at 740K (467C) is even hotter than the surface of Mercury, which is a (relatively!) pleasant 440K. Per unit of surface area, the atmosphere of Venus has as much mass as about 100 Earth atmospheres, and it is almost pure CO2. This accounts for its very strong greenhouse effect. In contrast, the CO2 in the Earth’s atmosphere accounts for a mere .00056 of the full mass of one Earth atmosphere.
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Getting the balance right…

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We’ve commented before on the “false objectivity of balance”, i.e. the tendency for many journalists to treat scientific issues–for which differing positions often do not have equal merit– in the same “he said, she said” manner they might treat a story on policy or politics.

This approach can appear balanced, but it leaves it to the reader to figure out on their own which position is most likely correct. However, the reader is rarely as well equipped as the writer to determine the bottom line, and in practice this plays into the hands of those who might seek to confuse the public through clever disinformation campaigns.

Thankfully, some journalists “get it”, and take the time (and effort) to assess where the balance of evidence really lies and report it accordingly. Two recent articles discuss what it takes, the first, an interview with Andy Revkin of the NY Times by Paul Thacker and the second a recent Ideas piece in the Boston Globe by Christopher Shea.

Hopefully this attitude is catching on!