Global Warming

Increases levels of COS and greenhouse gases are the primary cause og human-induced warming, released by burning fuels, land clearing adn agriculture.

Greenhouse gases are necessary for survival as they trap some solar radiation that would be irradiated to space, without which it would be 30dc cooler. Over the last 100years, the atmospheric concentratino of CO2 has increased by 15% and inceases 0.4% per year. THere is not as much consesus as to the extent, speed or regularity of the rise. A doubling of atmosphereic CO2 levels would increase temperatures by 2/3dc - the effect most marked in higher latitudes

There have been sustained temperatures for around 1000 years adn then a sharp increas occured arounf the 1800s - proof of human influence on the climate. Data and methodologis used to produce this figure are questionable as accurate temperature reocrds are only avaliable for the past 150years.

Key Conclusion:- This build up greenhouse gases in the atmosphere will lead to several degrees of warming and evidence is found from a broad range of sources.

Melting Ice Caps:- Water relased into the oceans and lack of cooling from ice means oceans are getting warmer and expanding - The artic has lost 1.7million km2 since 1980 adn its predicted all ice could disappear by 2050

Permafrost:- As this thaws, it releases a lot of methane - a greenhouse gas which will add to global warming 

Rising Sea Levels:- At an average rate of 1.8mm a year from 1961- 2003 (17mm in the 20th century) THe stern report indicates potential rises of 28-43cm by 2080 but if all polar ice melted, the increase could be 4-6m. This coupled with higher tides and stormier weather poses a threat to low lying communties such as the Netherands, Bangladesh and East Anglia

The total increase from 1899 to 2001 is 0.76dc but this is accelerating. From 1995-2006, 11 years rank among te 12 warmest years since 1850 and the glocal surface temperatures warming trend ove the last 50 years averages at 0.13dc per decade. It is likely that land aras will warm faster than oceans, particularly those in high latitudes - this change will be most pronounced in the winters. It is likely that heat waves and hot extremes will increase.

To prove cause and efffect relationships requres long-term correlation of weather and climate data. Climatologists beleive this evidence is now accumulating

Extreme Weather Events:- World Meterolgical Organisation (2003) blamed global warming for the record number of extreme weather events. In 2006, the Atmospheric Research centre in Colorado claimed the increase in hurricane frequency and magnitude was  a direct resutl of climatic change. Wind and warmer conditions that fuel storms that form in the Caribbean , are increasing due to greenhouse gases

Reduced rainfall and salination of groundwater in coastal zones will reduce the water avaliable fro drinking and irrigation, putting millions of lives at risj. 3 billion people could suffer water stress by 2080 with North Africa, Middle Wast and India likely to be worst affected.

Food Shortage and Disease in Africa, the Middle East and India are expected to see significant reductions in cereal yields as a result of reduced rainfall. China and Asia are likely to have incerased risk of malariawith 290million exposed by 2080