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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

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…

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!

Heat Rising at the Washington Post

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The Washington Post has published a second op-ed in as many days about global warming (“Spinning Global Warming”, By Robert D. Novak, Page A19, April 03, 2006–story is no longer available on the website, but the Chicago Sun Times version is available here). In this one, Novak claims that Hansen in 1988 over-predicted global warming by 400% (a story originated by Pat Michaels and subsequently propagated by Michael Crichton). This story is a fabrication that has already been set right by us in 2004.

Smearing Hansen, a leading climate scientist and member of the National Academy of Sciences, appears to have become sport among contrarian commentators (see our earlier discussions here and here). As ad hominem attacks and “shoot the messenger” strategies are often the last refuge for those losing the substantive debate, this might be viewed by some as a positive sign, indicative of just how intellectually bankrupt the contrarian movement has become.
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Significant Warming of the Antarctic Winter Troposphere

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The “iconic” Antarctic temperature trends are the large warming seen on the Antarctic Peninsula, which has had various repercussions including the collapse of several ice shelves (some documented in a previous post). Elsewhere, though, the pattern of surface warming is more complex – trends are smaller, and while more are positive than negative they are generally not significant – see this map. Contrary to what you might have heard, this is in general agreement with model predictions.

But meanwhile, there is a record for the upper atmosphere derived from radiosondes, which we have been working on – finding old datasets and digitising them to fill in gaps. What this shows is that around East Antarctica there is a general warming of the troposphere, greatest at around mid-height (at 600 hPa) at 0.7 ºC/decade over the last 30+ years.

In itself, this is an interesting observation. The obvious question is, what does it mean? Is this natural variability; is it a response to global warming, or to changes in ozone; or something else? Ozone is unlikely, because this is winter (which conveniently means that the radiosonde temperature corrections, often a source of potential trouble, are not a problem). Two ways of trying to interpret the record are to see what GCMs run for the same period show; or to look at the re-analyses (essentially, the archived outputs from the weather-prediction models). The latter, of course, incorporate many of the radiosonde observations that we are using, and so don’t count as independant. Despite this, the ECMWF re-analyses show *greater* trends than we see in the observations; and a maximum trend over West Antarctica (which has no radisonde stations to allow us to verify this). A climate model (HadCM3, with an ensemble of four members) shows similar patterns to the observations, but this time too little warming; and a good deal of variation between the ensemble members. So neither of these is helps much with the interpretation.

So we are currently left with an open question; hopefully, this will stimulate us and other researchers to explain it in the future.

[Quick addendum: the paper itself is available via this.]

Bush on “The Fundamental Debate”

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The President of the United States, George W. Bush, recently voiced his opinions on the science of climate change:

We — first of all, there is — the globe is warming. The fundamental debate: Is it manmade or natural. Put that aside.

The first part is the silver lining: despite receiving novelist Michael Crichton in the White House recently, Bush obviously has not bought his theory that the globe is in fact not warming. Crichton is one of the last trend sceptics who deny the warming trend is real.
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