The physics of global climate change: challenges for research

Full text: There are major issues in our scientific understanding of the functioning of our planet Earth. The growing atmospheric concentrations of greenhouse gases, changing in surface albedo, changes in distribution and lifetime of clouds, alteration in aerosol properties and distribution, are all key issues in the radiation balance that controls the climate of our planet. Earth is a non linear highly complex system. Since the industrial revolution, concentration of greenhouse gases, in particular carbon dioxide and methane have increase by 30 to 100%. The fraction of infrared radiation trapped in the atmosphere has increased by about 1.6 watts/m2. This additional energy has increased the average temperature by 0.79 degrees centigrade, with certain regions. But, we know very little of the physics, chemistry and biology that controls emissions, sinks and effects in Earth climate. Every week new important scientific findings are published in this area, and models that could predict the future of Earth climate are quite primitive and lack key issues. The hard science of global change is closely associated with socio-economic issues. Humanity have taken the main control role on Earth climate, and the potential for an average increase in temperature of 3 to 5 degrees is large, although there are tentative to limit the average temperature growth to 2 degrees. But even with this ambitious target, Amazonia and the Arctic will probably be much hotter than 3-4 degrees, with important feedbacks in the climate system. The talk will deal with these issues and new research that is needed to increase our knowledge on how the climate of our planet works and which climate we could have in the next decades. (author)