Ecrit par 25 scientifiques, voici un bon antibiotique a la fièvre verte.
Voici un apercu:
While AR4 is an impressive document, it is far from being a reliable reference work on some of the most important aspects of climate change science and policy. It is marred by errors and misstatements, ignores scientific data that were available but were inconsistent with the authors’ pre-conceived conclusions, and has already been contradicted in important parts by research published since May 2006, the IPCC’s cut-off date.
Ce rapport se concentre sur deux problèmes majeurs de l'IPCC:
Puis quelques points moins cruciaux sont abordes:
- The very weak evidence that the causes of the current warming are anthropogenic (Section 2)
- The far more robust evidence that the causes of the current warming are natural (Section 3).
- Computer models are unreliable guides to futureclimate conditions (Section 4)
- Sea-level rise is not significantly affected by rise in GH gases (Section 5)
- The data on ocean heat content have been misused to suggest anthropogenic warming. The role of GH gases in the reported rise in ocean temperature is largely unknown (Section 6)
- Understanding of the atmospheric carbon dioxide budget is incomplete (Section 7)
- Higher concentrations of CO2 are more likely to be beneficial to plant and animal life and to human health than lower concentrations (Section 8)
- The economic effects of modest warming arelikely to be positive and beneficial to human health (Section 9)
- Conclusion: Our imperfect understanding of the causes and consequences of climate change
means the science is far from settled. This, in turn, means proposed efforts to mitigate climate
change by reducing GH gas emissions are premature and misguided. Any attempt to influence global temperatures by reducing suchemissions would be both futile and expensive (Section 10).
Quelques myth Busted!:
For about two million years ice ages have been the dominant climate feature, interspersed with relatively brief warm periods of 10,000 years or so. Ice-core data clearly show that temperatures change centuries before concentrations of atmospheric carbon dioxide change. [Fischer et al. 1999; Petit, Jouzel et al. 1999] Thus, there is no empirical basis for asserting that changes in concentrations of atmospheric carbon dioxide are the principal cause of past temperature and climate change.
The proposition that changing temperatures cause changes in atmospheric carbon dioxide concentrations is consistent with experiments that show carbon dioxide is the atmospheric gas most readily absorbed by water (including rain) and that cold water can contain more gas than warm water. The conclusion that falling temperatures cause falling carbon dioxide concentrations is verified by experiment.
Carbon dioxide advocates advance no experimentally verified mechanisms explaining how carbon dioxide concentrations can fall in a few centuries without falling temperatures. Carbon dioxide is a minor greenhouse gas and is tertiary in greenhouse effect behind water vapor (WV) and high-level clouds. All other things being equal, doubling carbon dioxide in the atmosphere will increase temperatures by about 1 degree Celsius. Yet, as discussed below, the computer models used by the IPCC consistently exaggerate this warming by including a positive feedback from WV, without any empirical justification.
In his classic Climate, History, and the Modern World, H.H. Lamb  traced the changes in climate since the last ice age ended about 10,000 years ago. He found extensive periods warmer than today and cooler than today. The last warm period ended less than 800 years ago. When comparing these climate changes with changes in civilization and human welfare, Lamb concluded that, generally, warm periods are beneficial to mankind and cold periods harmful. Yet the anthropogenic global warming (AGW) advocates have ignored Lamb’s conclusions and assert that warm periods are harmful – without historical reference or knowledge
2. How much of modern warming is anthropogenic?
- The so-called ‘hockey-stick’ diagram of warming has been discredited.
- The correlation between temperature and carbon dioxide levels is weak and inconclusive.
- Observed and predicted ‘fingerprints’ don’t match.
Conclusion: The claim that man is the primary cause of the recent warming is not supported by science. The scientific evidence cited by the IPCC is largely contradicted by observations and analysis.
3. Most of modern warming is due to natural causes
4. Climate models are not reliable
Conclusion: The climate models used by the IPCC do not depict the chaotic, open-ended climate system. They cannot make reliable predictions and should not be used in formulating government policy.
5. The rate of sea-level rise is unlikely to increase
6. Do anthropogenic greenhouse gases heat the oceans?
7. How much do we know about carbon dioxide in the atmosphere?
Conclusion: While, evidently, there are still many unknowns about CO2 lifetimes, sources, and sinks, the overwhelming uncertainty is not in the science but in the emission scenarios that depend on many socio-economic assumptions.
8. The effects of human carbon dioxide emissions are benign
9. The economic effects of modest warming are likely to be positive
To sum up: This NIPCC report falsifies the principal IPCC conclusion that the reported warming (since 1979) is very likely caused by thehuman emission of greenhouse gases. In other words, increasing carbon dioxide is not responsible for current warming. Policies adopted and called for in the name of ‘fighting global warming’ are unnecessary. It is regrettable that the public debate over climate change, fueled by the errors and exaggerations contained in the reports of the IPCC, has strayed so far from scientific truth. It is an embarrassment to science that hype has replaced reason in the global debate over so important an issue.