-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 °C Anticipating changes in aerosols Predicting how aerosols change once in the atmosphere, and thus anticipating their impact, is no easy task. A scenario proposed by chemists sheds new light on the transformation of these organic particles. Their study shows that sunlight activates photosensitized reactions on the surface of the aerosols, promoting uptake of volatile organic compounds and leading to an increase in aerosol size and mass at rates that are consistent with those measured in the atmosphere. Proceedings of the National Academy of Sciences April 2012 online Dating fossil corals confirms important climate event Dating corals collected from reefs in Tahiti revealed that 14,600 years ago, sea levels suddenly rose by nearly 14 meters in a mere 350 years – an extremely rapid rise, which coincided with the beginning of the warm period that marked the end of the last glaciation. Using geophysical models, scientists from France, Japan and the UK estimated that the Antarctic ice sheet probably contributed as much as half of this sea level rise. These findings could prompt scientists to reappraise the sensitivity of the Antarctic ice sheet to current and future global warming. 47 Nature March 2012 online Climate change: new input from French research ----------------------------------------------------------------------- In 2012, French climate scientists published the results of past, recent and future global climate change simulations. The work has been made available to the national and international community, and will in particular be used by the Intergovernmental Panel on Climate Change (IPCC) in its next report, due to be published in 2013. These new results confirm and refine earlier data on future changes in temperature and precipitation as well as on sea ice melting. For scenarios in which greenhouse gas emissions continue to rise, the researchers have shown that by 2100, the global temperature of the Earth is likely to increase by 3.5 to 5°C compared to the pre-industrial era. However, this could be brought down to around 2°C if emissions were reduced rapidly and significantly. Analyses of all these simulations and those from other international groups should shed new light on the connection between human activities and climate over the decades and centuries to come. Reconstructing climate fluctuations in the 18th and 19th centuries By digitizing the weather records of the French Royal Society of Medicine’s archive collection, the researchers from the CHEDAR (Climate and Health Data Rescue and Modeling) project have completed the first stage in a program aimed at reconstructing the climate fluctuations that marked France in the 18th and 19th centuries. The scientists will now combine this data with other sources of information and use it as a benchmark to assess the ability of numerical models to simulate the climatic disasters described by historians of the time. Located in the west of Réunion Island at an altitude of 2,200 meters, a new atmospheric observatory inaugurated in October 2012 will provide invaluable information about atmospheric composition in the tropical southern hemisphere, where observations are still scarce. ---------------------------------------------------------- Understanding how storms are triggered By analyzing ten years’ worth of satellite data covering the entire planet, a European team has discovered that daytime storms that develop over regions where humidity is not evenly distributed tend to strike the driest areas. The researchers then showed that current climate models do not capture such phenomena well, and even give opposite results. Improving the way in which models account for this phenomenon should help scientists to decipher climate change at regional scales. Nature September 2012 online Researchers examining coral samples. Reef-building corals grow near the surface of the water within a very narrow depth range, which makes them good indicators of sea level. Differences in the global mean surface temperature of the Earth between the periods 2071-2100 and 1971-2000, as calculated by two models. 2012 A year at CNRS
RA2012_en
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