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Edouard Bard climatologist, explains how scientific tools are the most efficient fears of a climate shift of a magnitude and speed dangerous to human societies, from the second half of the century. To mitigate this risk, technological change and economic need. To mitigate this risk, technological change and economic need.
Oceanograph, paléoclimatolo-gue and geochemist, he leads a team to the European Centre for Research and Teaching in Geosciences of the Environment (CEREGE) in Aix-en-Provence. Oceanograph, paléoclimatolo-gue and geochemist, he leads a team to the European Centre for Research and Teaching in Geosciences of the Environment (CEREGE) in Aix-en-Provence. His research has resulted in more than one hundred scientific papers. His research has resulted in more than one hundred scientific papers. Multimédaillé by the European Union of Geosciences, the American Geophysical Union, French citation laureate (1981-1998) of the Institute of Scientific Information, it has just received the first prize Gérard Mégie CNRS and the Academy of Sciences. Multimédaillé by the European Union of Geosciences, the American Geophysical Union, French citation laureate (1981-1998) of the Institute of Scientific Information, it has just received the first prize Gérard Mégie CNRS and the Academy of Sciences.
Scientists are at the root of the UN convention on climate change, signed in 1992. Scientists are at the root of the UN convention on climate change, signed in 1992. Public opinion has often feel they are repeated since. Public opinion has often feel they are repeated since. Is this the case? Is this the case?
It is a real impression ... It is a real impression ... And false! And false! Scientists gives the feeling of repetition, because, as a sort of irony of nature, the estimation of the magnitude of the disruption of climate by man was good even before it could l 'studied quantitatively. Scientists gives the feeling of repetition, because, as a sort of irony of nature, the estimation of the magnitude of the disruption of climate by man was good even before it could the studied quantitatively. One can even go back to work the Swedish chemist Svante Arrhenius: from 1896, it foresees an increase in the average temperature of the Earth as a consequence of the use of fossil fuels. One can even go back to work the Swedish chemist Svante Arrhenius: from 1896, it foresees an increase in the average temperature of the Earth as a consequence of the use of fossil fuels. Arrhenius estimated that a doubling of carbon dioxide content of the air would result in a global warming of about 5 to 6 ° C. Arrhenius estimated that a doubling of carbon dioxide content of the air would result in a global warming of about 5 to 6 ° C. It is quite amazing that this forecast is not far removed from those published today. It is quite amazing to note that this estimate is not far removed from those published today. The agreement is almost miraculous, because Arrhenius did not have very reliable data on the greenhouse gas and had not considered the multitude of climate feedbacks. The agreement is almost miraculous, because Arrhenius did not have very reliable data on greenhouse gases and had not considered the multitude of climate feedbacks. The little apparent discrepancy between the results of the first, rudimentary computer simulations of future climate in the 80's and those of today, a lot more realistic, reflects the same. The little apparent discrepancy between the results of the first, rudimentary computer simulations of future climate in the 80's and those of today, a lot more realistic, reflects the same. This apparent continuity hides an enormous effort of research and many scientific discoveries. This apparent continuity hides an enormous effort of research and many scientific discoveries.
The alert was launched in the late 80 was based on computer simulations. The alert was launched in the late 80 was based on computer simulations. How have evolved these simulations and their results? How have evolved these simulations and their results?
Twenty years ago, only the numerical models that took into account the dynamics of the atmosphere. Twenty years ago, only the numerical models that took into account the dynamics of the atmosphere. In addition, the simulations were limited to a calculation climate "in the balance" for a doubling of the atmospheric content carbon dioxide (about 550 parts per million). In addition, the simulations were limited to a calculation climate "in the balance" for a doubling of the atmospheric carbon dioxide content (about 550 parts per million). Today, the capabilities of computers allow representations much larger and these models have made tremendous progress. Today, the capabilities of computers allow representations much larger and these models have made tremendous progress. The global ocean, with its profound movement, is better represented. The global ocean, with its profound movement, is better represented. Des becoming more realistic interactions between the atmosphere, ocean, ice, geochemical cycles and the Biosphere, which are also new sources of uncertainties. Des becoming more realistic interactions between the atmosphere, ocean, ice, geochemical cycles and the Biosphere, which are also new sources of uncertainties. The finer points, such as multiple and complex action of aerosols and clouds, have been the subject of intense research. The finer points, such as multiple and complex action of aerosols and clouds, have been the subject of intense research. Our understanding of the physical-chemical and biological weapons as well as their mathematical representation have also made significant progress. Our understanding of the physical-chemical and biological weapons as well as their mathematical representation have also made significant progress. While it remains simplifications and unable to represent an explicit processes that occur at small spatial scales. While it remains simplifications and unable to represent an explicit processes that occur at small spatial scales. In addition, many teams, including France and China, have made full simulations with different models. In addition, many teams, including France and China, have made full simulations with different models. If the magnitude of the change in climate has not changed a warming of between 2 and 6 ° C above average in terms of global emission scenarios and sensitivity greater or lesser climate for this disturbance, this conclusion is much stronger than that at the time. If the magnitude of the change in climate has not changed a warming of between 2 and 6 ° C above average in terms of global emission scenarios and sensitivity greater or lesser climate for this disturbance, this conclusion is much stronger than that at the time. The threat of climate change during the second half of the century, on a scale and speed dangerous to human societies has been confirmed. The threat of climate change during the second half of the century, on a scale and speed dangerous to human societies has been confirmed.
As the climate changes measured since 1990 she comforted or reduces the confidence that you place in the computer simulations? As the climate changes measured since 1990 she comforted or reduces the confidence that you place in the computer simulations?
It happened more than fifteen years since the first report of the IPCC (Intergovernmental Panel on Climate Change) which culminated in the signing of the UN convention. It happened more than fifteen years since the first report of the IPCC (Intergovernmental Panel on Climate Change) which culminated in the signing of the UN convention. This is a significant duration. This is a significant duration. During this period, the growth of carbon dioxide emissions from the coal, oil and natural gas followed the scenarios highest, with more than 3% per annum between 2000 and 2005, compared with less than 1% between 1990 and 1999 . During this period, the growth of carbon dioxide emissions from the coal, oil and natural gas followed the highest scenarios, with more than 3% per annum between 2000 and 2005, compared with less than 1% between 1990 and 1999. If we add deforestation, it reached 9 billion tons of carbon per year, compared with fewer than eight in 90 years. If we add deforestation, it reached 9 billion tons of carbon per year, compared with fewer than eight in 90 years. Accordingly, the content of carbon dioxide in the atmosphere now reached 383 parts per million, measured in Hawaii, compared to 280 before the industrial revolution, a level not seen since a million years. Accordingly, the content of carbon dioxide in the atmosphere now reached 383 parts per million, measured in Hawaii, compared to 280 before the industrial revolution, a level not seen since a million years. Average temperatures have continued to increase, at a rate close to that required by the models, all the years 2000 are significantly above the 1960-1990 average. Average temperatures have continued to increase, at a rate close to what is provided by the models, all the years 2000 are significantly above the 1960-1990 average. The global sea level to rise by 3.1 millimeters per year since 1993, according to the satellites, a phenomenon linked to its thermal expansion and the melting of continental ice. The global sea level to rise by 3.1 millimeters per year since 1993, according to the satellites, a phenomenon linked to its thermal expansion and the melting of continental ice. The response of flora and fauna to climate change becomes clearer: longer periods of plant growth, displacement of wildlife. The response of flora and fauna to climate change becomes clearer: longer periods of plant growth, displacement of wildlife. If the magnitude of these changes is still small compared to what we fear for the second half of the century, they all argue in favour of the reliability of the models. If the magnitude of these changes is still small compared to what we fear for the second half of the century, they all argue in favour of the reliability of the models. |
Climate Change 
