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Resolving technical issues in science

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One of the strengths of science is its capacity to resolve controversies by generally accepted procedures and standards. Many scientific questions (especially more technical ones) are not matters of opinion but have a correct answer.

Scientists document their procedures and findings in the peer-reviewed literature in such a way that they can be double-checked and challenged by others. The proper way to challenge results is, of course, also through the peer-reviewed literature, so that the challenge follows the same standards of documentation as did the original finding.
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A biased economic analysis of geoengineering

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Translations: (Español)

Guest commentary by Alan Robock – Rutgers University

Bjorn Lomborg’s Climate Consensus Center just released an un-refereed report on geoengineering, An Analysis of Climate Engineering as a Response to Global Warming, by J Eric Bickel and Lee Lane. The “consensus” in the title of Lomborg’s center is based on a meeting of 50 economists last year. The problem with allowing economists to decide the proper response of society to global warming is that they base their analysis only on their own quantifications of the costs and benefits of different strategies. In this report, discussed below, they simply omit the costs of many of the potential negative aspects of producing a stratospheric cloud to block out sunlight or cloud brightening, and come to the conclusion that these strategies have a 25-5000 to 1 benefit/cost ratio. That the second author works for the American Enterprise Institute, a lobbying group that has been a leading global warming denier, is not surprising, except that now they are in favor of a solution to a problem they have claimed for years does not exist.

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Friday round-up

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Two items of interest this week. First, there is an atrocious paper that has just been published in JGR by McLean, de Freitas and Carter that is doing the rounds of the denialosphere. These authors make the completely unsurprising point that that there is a correlation between ENSO indices and global mean temperature – something that has been well known for decades – and then go on to claim that that all trends are explained by this correlation as well. This is somewhat surprising since their method of analysis (which involves taking the first derivative of any changes) eliminates the influence of any trends in the correlation. Tamino has an excellent demonstration of the fatuity of the statements in their hyped press-release and Michael Tobis deconstructs the details. For reference, we showed last year that the long term trends are still basically the same after you account for ENSO. Nevermore let it be said that you can’t get any old rubbish published in a peer-reviewed journal!

Second (and much more interestingly) there is an open call for anyone interested to contribute to setting the agenda for Earth System Science for the next couple of decades at the Visioning Earth Science website of the International Council for Science (ICS). This is one of the umbrella organisations that runs a network of committees and programs that prioritise research directions and international programs and they are looking for ideas. Let them know what your priorities are.

More bubkes

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Translations: (Chinese (simplified))

Roger Pielke Sr. has raised very strong allegations against RealClimate in a recent blog post. Since they come from a scientific colleague, we consider it worthwhile responding directly.

The statement Pielke considers “misinformation” is a single sentence from a recent posting:

Some aspects of climate change are progressing faster than was expected a few years ago – such as rising sea levels, the increase of heat stored in the ocean and the shrinking Arctic sea ice.

First of all, we are surprised that Pielke levelled such strong allegations against RealClimate, since the statement above merely summarises some key findings of the Synthesis Report of the Copenhagen Climate Congress, which we discussed last month. This is a peer-reviewed document authored by 12 leading scientists and “based on the 16 plenary talks given at the Congress as well as input of over 80 chairs and co-chairs of the 58 parallel sessions held at the Congress.” If Pielke disagrees with the findings of these scientists, you’d have thought he’d take it up with them rather than aiming shrill accusations at us. But in any case let us look at the three items of alleged misinformation:

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Winds of change

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Gavin Schmidt and Michael Mann

There was an interesting AP story this week about possible changes in wind speed over the continental US. The study (by Pryor et al (sub.)), put together a lot of observational data, reanalyses (from the weather forecasting models) and regional models, and concluded that there was some evidence for a decrease in wind speeds, particularly in the Eastern US. However, although this trend appeared in the observational data, it isn’t seen in all the reanalyses or regional models, leaving open a possibility that the trend is an artifact of some sort (instrumental changes, urbanization etc.). If the effect is real though, one would want to see whether it could be tied to anything else (such as forcing from greenhouse gas or aerosol increases), and indeed, whether it had any implications for wind-generated electricity, water evaporation etc.

Amusingly, both of us were quoted in the story as having ostensibly conflicting views. Mike was quoted as finding the evidence for a trend reasonably convincing, while Gavin was quoted as being unconvinced of the evidence for an anthropogenic climate change signal (note that the two statements are not in fact mutually inconsistent). As one should expect in any news story, these single lines don’t really do justice to the longlonger interviews both of us gave the reporter Seth Borenstein. So what is the bigger context?
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Of tempests, barren ground and a thousand furlongs of sea

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Guest commentary by Ron Miller, NASA GISS

Several studies have shown that hurricane activity is generally reduced during years when there is a thick aerosol haze over the subtropical Atlantic. The haze is comprised mainly of soil particles, stripped by wind erosion from the barren ground over the Sahara and Sahel. These particles are lifted into the atmosphere and carried by the Trade winds as far as the Caribbean and Amazon basin. Plumes of dust streaming off the African coast are easily recognized in satellite imagery, and were even described by Charles Darwin during his voyage on the Beagle.

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Welcome to the fray

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As imitation is the sincerest form of flattery, we’ve naturally been delighted that a number of sites have sprung up over the past few years with missions complementary to our own focussing on the science of climate change. Last year, we were introduced to “climate ethics”, whose mission it is to focus on the ethical dimensions of climate change. Now there is “RealClimateEconomics”, whose aim it is to focus on the economic considerations surrounding climate change. Neither this site nor climateethics.org has any formal relationship with RealClimate, despite the similarity in name. We do nonetheless welcome them to the fray. We are pleased to add them to our blogroll, which we hope has become a useful resource for those wishing to explore the broader discourse on climate change that lies beyond the science.

Hit the brakes hard

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Translations: (Español)

There is a climate splash in Nature this week, including a cover showing a tera-tonne weight, presumably meant to be made of carbon (could it be graphite?), dangling by a thread over the planet, and containing two new articles (Allen et al and Meinshausen et al), a “News & Views” piece written by two of us, and a couple commentaries urging us to “prepare to adapt to at least 4° C” and to think about what the worst case scenario (at 1000 ppm CO2) might look like.

At the heart of it are the two papers which calculate the odds of exceeding a predefined threshold of 2°C as a function of CO2 emissions. Both find that the most directly relevant quantity is the total amount of CO2 ultimately released, rather than a target atmospheric CO2 concentration or emission rate. This is an extremely useful result, giving us a clear statement of how our policy goals should be framed. We have a total emission quota; if we keep going now, we will have to cut back more quickly later.

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Yet more aerosols: Comment on Shindell and Faluvegi

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Guest post from Drew Shindell, NASA GISS

Our recent paper “Climate response to regional radiative forcing during the twentieth century”, has generated some interesting discussion (some of it very ‘interesting’ indeed). So this post is an attempt to give a better context to the methods and implications of the study.

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Aerosol effects and climate, Part II: the role of nucleation and cosmic rays

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Translations: (Italian)

Guest post by Bart Verheggen, Department of Air Quality and Climate Change , Energy research Institute of the Netherlands (ECN)

In Part I, I discussed how aerosols nucleate and grow. In this post I’ll discuss how changes in nucleation and ionization might impact the net effects.

Cosmic rays

Galactic cosmic rays (GCR) are energetic particles originating from space entering Earth’s atmosphere. They are an important source of ionization in the atmosphere, besides terrestrial radioactivity from e.g. radon (naturally emitted by the Earth’s surface). Over the oceans and above 5 km altitude, GCR are the dominant source. Their intensity varies over the 11 year solar cycle, with a maximum near solar minimum. Carslaw et al. give a nice overview of potential relations between cosmic rays, clouds and climate. Over the first half of the 20th century solar irradiance has slightly increased, and cosmic rays have subsequently decreased. RC has had many previous posts on the purported links between GCR and climate, e.g. here, here and here.

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