Saturday, January 23, 2010

We wuz wrong

Source: IPCC Report

Source: Climate Change 2007: Working Group II: Impacts, Adaption and Vulnerability

In the ongoing back and forth between those trying to get governmental action on climate change and those who , let us say, are 'not persuaded', there recently has been a hubbub about the Intergovernmental Panel on Climate Change (IPCC)'s seminal report from 2007, the Fourth Assessment Report. Specifically in the section on The Himalayan Glaciers (see above, or go to 10.6.2), a number of mistakes were made... The report overstates the extent of the Himalayan glaciers (500,000 square kilometers, rather than 33,000 square kilometers); overstates their melt rate ("... glaciers in the Himalayas are receding faster than in any other part of the world...", incorrect); and says that "...likelihood of them disappearing by the 2035 and perhaps sooner is very high...", which is a huge mistake... (2350 might be closer).

Now, how these errors made it into the report is rather unclear. The first explanation reported regarding the origin of the '2035 error' was that it originated from an article in the popular science press that somehow made its way into the IPCC report. A subsequent (more convenient) explanation was that it was a typographical error, and that somehow the digits in 2350 were transposed to give 2035. It is unclear which was the actual way that the error was introduced, the IPCC did not explain, and its statement (see below) only referenced improperly applied "standards of evidence"...

Now one can readily understand why the IPCC would prefer that people accept the second possibility, rather than the first! After all, who hasn't made a similar typo at some point in their lives? A common mistake that can happen to anyone without reflecting on their competence. On the other hand the first explanation does serious damage to their credibility, competence, and intelligence. This is especially serious for a group that relies on 'appeals to authority' as a significant part of their argument... Ouch!

Note: this blogger does blame the IPCC for this use. Climate science is very complex, and when we are talking about evaluating this on a global scale we are talking about something extraordinarily complex, with very intricate computer models, tortuous mathematics, etc., all not easily explained to the lay person. "Appeal to authority' may be all they are left with...

World misled over Himalayan glacier meltdown
UN climate report riddled with errors on glaciers
IPCC statement on the melting of Himalayan glaciers (see below)
Pachauri admits mistake in IPCC report, rules out resignation

The Synthesis Report, the concluding document of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (page 49) stated: “Climate change is expected to exacerbate current stresses on water resources from population growth and economic and land-use change, including urbanisation. On a regional scale, mountain snow pack, glaciers and small ice caps play a crucial role in freshwater availability. Widespread mass losses from glaciers and reductions in snow cover over recent decades are projected to accelerate throughout the 21st century, reducing water availability, hydropower potential, and changing seasonality of flows in regions supplied by meltwater from major mountain ranges (e.g. Hindu-Kush, Himalaya, Andes), where more than one-sixth of the world population currently lives.”

This conclusion is robust, appropriate, and entirely consistent with the underlying science and the broader IPCC assessment.

It has, however, recently come to our attention that a paragraph in the 938-page Working Group II contribution to the underlying assessment2 refers to poorly substantiated estimates of rate of recession and date for the disappearance of Himalayan glaciers. In drafting the paragraph in question, the clear and well-established standards of evidence, required by the IPCC procedures, were not applied properly.

The Chair, Vice-Chairs, and Co-chairs of the IPCC regret the poor application of well-established IPCC procedures in this instance. This episode demonstrates that the quality of the assessment depends on absolute adherence to the IPCC standards, including thorough review of “the quality and validity of each source before incorporating results from the source into an IPCC Report”. We reaffirm our strong commitment to ensuring this level of performance.

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