THE FIRST official investigation of errors in the most recent assessment of global warming by the UN Intergovernmental Panel on Climate Change (IPCC) has concluded that none of these were so serious as to undermine its main conclusions.
PBL, the Netherlands Environmental Assessment Agency, which carried out the investigation at the request of the Dutch government, focused on the rate at which Himalayan glaciers are melting and the IPCC’s stated percentage of the Netherlands that lies below sea level. This had raised concerns in the Dutch parliament over the reliability of scientific information on which government climate policy was based. As a result, PBL was asked to assess how such errors would affect the IPCC’s main conclusions on the regional impacts of climate change.
Its report, published yesterday, said the panel’s fourth assessment – issued in 2007 – “conclusively shows that these effects already are visible in many places around the world, and that these will become more serious under further temperature increases”.
However, PBL said the foundation for some of these conclusions “could have been made more transparent”, and it recommended that there should be more investment in quality control “in order to avoid mistakes and shortcomings, to the extent possible”.
This could be done by involving more people in the compilation of the panel’s assessments. “Interested parties could be given the opportunity . . . to report on possible errors,” the report said. “Such a level of openness could further restore credibility of the IPCC.” The investigation, carried out under the supervision of the Royal Netherlands Academy of Arts and Sciences, criticised the panel’s omission of less severe and in some cases even positive effects of climate change from its summaries for policymakers.
It also found that the IPCC’s 32-point summary on regional impacts did not mention other important factors, such as the influence of population growth on water shortages, and it recommends that this should be reflected in the fifth assessment, due in 2014.
Dealing with particular errors, PBL said the Himalayan glaciers “will most definitely not have disappeared by 2035, as was stated in the IPCC report. Had this been correct, then the glaciers would have to melt 25 times faster than they have in the recent past”.
Regarding the 55 per cent of Dutch land stated to be below sea level, it said this should have read that “55 per cent of the Netherlands is prone to flooding”, with 26 per cent of the land below sea level and another 29 per cent susceptible to river flooding.
“The IPCC is an international network in which scientists from all over the world participate . . . PBL has indicated that, in a document that is thousands of pages long, representing the state-of-the-art in science, errors seem in actual practice unavoidable.”