Wednesday, April 28, 2010

Scientific American falls prey to denialist memes

The May issue of Scientific American just landed in my mailbox, and an article in the "News Scan" section entitled "IPCC Errors Prompt a Review on Climate Science Data" caught my attention.

The opening sentence reads:
African crop yields wither, along with the Amazon rain forest; Himalayan glaciers disappear by 2035. These are the erroneous predictions ascribed to the most recent report from the UN IPCC [...] So do the few errors in a report exceeding 3,000 pages merit a revision of IPCC processes?
OK, fair enough - except that only one of the three predictions were actually "erroneous". The IPCC WG2 report said:
In other countries, additional risks that could be exacerbated by climate change include greater erosion, deficiencies in yields from rain-fed agriculture of up to 50% during the 2000-2020 period, and reductions in crop growth period (Agoumi, 2003). [...]However, not all changes in climate and climate variability will be negative, as agriculture and the growing seasons in certain areas (for example, parts of the Ethiopian highlands and parts of southern Africa such as Mozambique), may lengthen under climate change, due to a combination of increased temperature and rainfall changes (Thornton et al., 2006). Mild climate scenarios project further benefits across African croplands for irrigated and, especially, dryland farms.
As RealClimate reported, the only "scandal" here is that grey literature was referenced for the 50% claim. The figure isn't factually incorrect - as far as I know - and there's certainly no policy or rule that prevents the IPCC  (especially Working Group II, which focuses on climate change impacts on society and ecosystems) from using grey literature reports. Of course, that didn't prevent Jonathan Leake - perhaps the most inept (or dishonest) science reporter to still hold a job - over at the Sunday Times from turning this into "Africagate".

The second claimed error concerns the IPCC reporting that the Amazon rainforest could react rapidly to a drying climate:
Up to 40% of the Amazonian forests could react drastically to even a slight reduction in precipitation; this means that the tropical vegetation, hydrology and climate system in South America could change very rapidly to another steady state, not necessarily producing gradual changes between the current and the future situation (Rowell and Moore, 2000).
Again, the alleged scandal here is that the Rowell and Moore reference is gray literature (a WWF report). But is it wrong? No. The WWF report cited a 1999 Nature paper, and the author of that paper has confirmed that the figure is correct. RealClimate, Island of Doubt, and Deltoid discuss this in more detail.

To top it off, the SciAm article goes on to say:
. . . one of the IPCC errors came as a result of information provided directly by the Dutch government about the percentage of the Netherlands that lies below sea level and is therefore vulnerable to flooding from rising seas. The government corrected the percentage in a subsequent statement, from 55 to 26 percent of the country as lying below sea level. [emphasis added]
So let me get this straight: the Dutch government made the mistake, and somehow this is an IPCC error?

It's disappointing that a publication as reputable as Scientific American would uncritically repeat these denialist memes.

Thursday, April 15, 2010

Volcanic Predictions

With the eruption of the Eyjafjallajökull volcano in Iceland, I'd like to make two predictions about the climate denial blogosphere:
1) If the dust and sulphur dioxide result in a global cool spell, climate denialists will once again proclaim the death of global warming.
2) If this year's Arctic ice melt demonstrates either a faster-than-usual rate of decline, and/or sets a new ice minimum record this September, climate denialists will chalk it up entirely to this eruption.