Tareas

GLOBAL WARMING

Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years,Earth's average surface temperature increased by about 0.8 °C (1.4 °F) with about two thirds of the increase occurring over just the last three decades Warming ofthe climate system is unequivocal, and scientists are more than 90% certain most of it is caused by increasing concentrations of greenhouse gases produced by humanactivities such as deforestation and burning fossil fuels. These findings are recognized by the national science academies of all the major industrialized countries.An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, and a probable expansion of subtropicaldeserts. Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effectsof the warming include more frequent occurrence of extreme weather events including heat waves, droughts and heavy rainfall events, species extinctions due toshifting temperature regimes, and changes in crop yields. Warming and related changes will vary from region to region around the globe, with projections being more robustin some areas than others. In a 4 °C world, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptationfor natural systems would largely be exceeded throughout the world. Hence, the ecosystem services upon which human livelihoods depend would not be preserved.