Friday, May 6, 2011

Climate change


Climate change is any long term significant change in the “average weather” of a region or of the earth as a whole. Average weather may include average temperature, precipitation and wind patterns. It involves changes in the consistency or average condition of the atmosphere over durations ranging from decades to million of years.  These changes may be caused by dynamic processes of the earth, external forces including variations in sunlight intensity, and more recently by human activities.
What is climate change? Global climate change is caused by the accumulation of greenhouses gases in the lower atmosphere. The global concentration of these gases is increasing, mainly due to human activities, such as the combustion of fossil fuels (which release carbon dioxide) and deforestation (because forest removes from the atmosphere). The atmospheric concentration of carbon dioxide, the main greenhouse gas, has increased by 30 percent since preindustrial times.
Effects on natural environment: Over 100 years ago, people worldwide began burning more coal and oil for homes, factories and transportation. Burning these fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere. Below are the effects of the climate change that we see happening now-
1)      Sea level rising: During the 20th century, sea level rose about 15 cm (6 inches) due to melting glacier ice and expansion of warmer seawater. Models predict that sea level may rise as much as 59 cm (23 inches) during the 21st century, threatening coastal communities, wetlands and coral reefs. 
2)      Arctic sea ice is melting:  The summer thickness of sea ice is about half of what it was in 1950. Melting ice may lead to changes in the ocean circulation. Plus melting sea ice is speeding up the warming in the Arctic. 3)   Glaciers and permafrost are melting: Over the past 100 years, mountain glaciers in the areas of the world have decreased in size and so has the amount of permafrost in the Arctic. Greenland's ice sheet is melting faster too.  
4)     Sea-surface temperatures are warming:  Warmer waters in the shallow oceans have contributed to the death of about a quarter of the world's coral reefs in the last few decades.
5)      Heavier rainfall cause flooding:  Warmer temperature has lead to more intense rainfall events in some areas. This can cause flooding. 
6)  Extreme drought is increasing: Higher temperatures cause a high rate of evaporation and more droughts in some areas in the world. 
7)  Ecosystems are changing: At temperatures warm, species may either move to cooler habitat or die. Species that are particularly vulnerable include endangered species, coal reefs and polar animals.
8)    Heat waves more frequent: It is likely that heat waves have become more common in more areas in the world.Human influence on climate change

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