and the UK. It states: "We recognise the IPCC as the world's most reliable source of information on climate change and its causes, and we endorse its method of achieving consensus." In 2001, the executive branch of the US federal government asked the US National Research Council (US NRC, 2001) to produce an assessment of climate change science. Part of the assessment by US NRC (2001) looks at the report produced by Working Group I (WG I) in the TAR. Working Group I's contribution to the TAR assesses the physical scientific aspects of the climate system and climate change. US NRC (2001) generally agrees with findings of the WG I report, for example, US NRC (2001) state that "[the] IPCC’s conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue." US NRC (2001) emphasise the need for governments to have a good understanding of uncertainties in climate change science. The example cited by US NRC (2001) is the uncertainty over future changes in GHG emissions, which may be less or more than that projected by the TAR. US NRC (2001) also state: The most valuable contribution U.S. scientists can make is to continually question basic assumptions and conclusions, promote clear and careful appraisal and presentation of the uncertainties about climate change as well as those areas in which science is leading to robust conclusions, and work toward a significant improvement in the ability to project the future. Reception Endorsements In 2001, 16 national science academies issued a joint statement on climate change. The joint statement was made by the Australian Academy of Science, the Royal Flemish Academy of Belgium for Science and the Arts, the Brazilian Academy of Sciences, the Royal Society of Canada, the Caribbean Academy of Sciences, the Chinese Academy of Sciences, the French Academy of Sciences, the German Academy of Natural Scientists Leopoldina, the Indian National Science Academy, the Indonesian Academy of Sciences, the Royal Irish Academy, Accademia Nazionale dei Lincei (Italy), the Academy of Sciences Malaysia, the Academy Council of the Royal Society of New Zealand, the Royal Swedish Academy of Sciences, and the Royal Society (UK). The statement, also published as an editorial in the journal Science, stated "we support the [TAR's] conclusion that it is at least