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Climate change is with us. A decade ago, it was conjecture. Now the future is unfolding before our eyes. Canada’s Inuit see it in melting Arctic ice and permafrost. The shantytown dwellers of Latin America and Southern Asia see it in lethal storms and floods. Europeans see it in disappearing glaciers, forest fires and fatal heat waves. Scientists see it in tree rings, ancient coral and bubbles trapped in ice cores. These reveal 5 that the world has not been as warm as it is now for a mil¬lennium or more. Earth has probably never warmed as fast as in the past 30 years - a period when natural influences on global temperatures. Such as solar cycles and volcanoes should have cooled us down.
People are causing the change by burning nature’s vast stores of coal, oil and natural gas. This releases billions of tonnes of carbon dioxida (C02) every year although the changes may actually have started with 10 the dawn of agriculture, say some scientists. The physics of the “greenhouse effect” has been a matter of scientific fact for a century. C02 is a greenhouse gas that traps the sun’s radiation within the troposphere. It has accumulated along with other man-made greenhouse gases, such as methane and chlorofluorocarbons (CFCs). If current trend continue,
we will raise atmospheric C02 concentrations to double pre-industrial levels during this century. That will probably be enough to raise global temperatures by around 2°C to 5°C. 15 Some warming is certain, but the degree will be determined by feedbacks involving melting ice, the oceans, water va¬por, clouds and changes to vegetation.
Global warming is bringing about other unpredict¬able changes. Melting glaciers and precipitation are caus¬ing some rivers to overflow, while evaporation is emptying others. Diseases are spreading. Some crops grow faster while othes see yields slashed by disease and drought. Strong hurricanes are becoming more 20 frequent and destructive. Arctic sea ice is melting faster every year, and there are growing fears of a shutdown of the ocean currents that keep Europe warm for its latitude. Clashes over dwindling water resources may cause conflicts in many regions.
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