J. Demesure,

Dans vos multiples commentaires, vous cherchez à faire croire qu’il n’existe pas un large consensus scientifique sur la réalité du réchauffement climatique, son origine anthropique et l’urgence à agir pour réduire les émissions de gaz à effet de serre.

Or, IL EXISTE BIEN UN TEL CONSENSUS SCIENTIFIQUE et chacun devrait le savoir car il est grand temps d’agir.

En effet, qui l’affirme ?

Réponse :

- Le Groupe d’experts intergouvernemental sur l’évolution du climat (GIEC) dans son Troisième rapport d’évaluation sur le changement climatique préparé par plus de 2000 experts.

- 16 Académies des sciences (des pays du G8, d’Inde, de Chine, du Brésil et de cinq autres pays) : voir leur déclaration commune à http://www.academie-sciences.fr/actualites/textes/G8_fr.pdf

- Toutes les plus prestigieuses institutions scientifiques américaines, dont The American Meteorlogical Society, The American Geophysical Union et The American Association for the Advancement of Science.

- Les deux plus prestigieuses revues scientifiques mondiales, Nature et Science (voir par exemple l’éditorial « The Scientific Consensus on Climate Change » dans Science du 3 décembre 2004)

Chacun est libre de croire qu’il veut, mais il n’y a pas plus crédible que les sources ci-dessus en matière de réchauffement climatique, quoi qu’en dise J. Demesure.

Enfin, pour les lecteurs (maitrisant l’anglais) qui voudraient en savoir plus sur ce consensus scientifique et sur les tentatives de désinformation des lobbys pétroliers américains, je recommande la lecture de l’excellent guide sur le sujet intitulé « A guide to facts and fictions about climate change » publié par la Royal Society (l’Académie des sciences du Royaume-Uni) à http://www.royalsoc.ac.uk/downloaddoc.asp?id=1630. Je vous en cite une partie très édifiante :

“ Misleading arguments 2. Many scientists do not think that climate change is a problem. Some scientists have signed petitions stating that climate change is not a problem.

There are some differences of opinion among scientists about some of the details of climate change and the contribution of human activities, such as the burning of fossil fuels. Researchers continue to collect more data about climate change and to investigate different explanations for the evidence. However, the overwhelming majority of scientists who work on climate change agree on the main points, even if there is still some uncertainty about particular aspects, such as how the concentration of greenhouse gases in the atmosphere will change in the future.

In the journal Science in 2004, Oreskes published the results of a survey of 928 papers on climate change published in peer-reviewed journals between 1993 and 2003. She found that three-quarters of the papers either explicitly or implicitly accepted the view expressed in the IPCC 2001 report that human activities have had a major impact on climate change in the last 50 years, and none rejected it.

There are some individuals and organisations, some of which are funded by the US oil industry, that seek to undermine the science of climate change and the work of the IPCC. They appear motivated in their arguments by opposition to the United Nations Framework Convention on Climate Change and the Kyoto Protocol, which seek urgent action to tackle climate change through a reduction in greenhouse gas emissions.

Often all these individuals and organisations have in common is their opposition to the growing consensus of the scientific community that urgent action is required through a reduction in greenhouse gas emissions. But the opponents are well-organised and well-funded. For instance, a petition was circulated between 1999 and 2001 by a campaigning organisation called the Oregon Institute of Science and Medicine (OISM), which called on the US Government to reject the Kyoto Protocol. The petition claimed that “proposed limits on greenhouse gases would harm the environment, hinder the advance of science and technology, and damage the health and welfare of mankind”.

These extreme claims directly contradict the conclusions of the IPCC 2001 report, which states that “reducing emissions of greenhouse gases to stabilize their atmospheric concentrations would delay and reduce damages caused by climate change”.

The petition was circulated together with a document written by individuals affiliated to OISM and to the George C Marshall Institute, another campaigning organisation. On 20 April 1998, the US National Academy of Sciences (NAS) issued a warning about the document circulated with the petition because it had been presented “in a format that is nearly identical to that of scientific articles published in the Proceedings of the National Academy of Sciences.” The statement pointed out : “The NAS Council would like to make it clear that this petition has nothing to do with the National Academy of Sciences and that the manuscript was not published in the Proceedings of the National Academy of Sciences or in any other peer-reviewed journal”.”