A process invoked by the increasing concentration of greenhouse gases in the earths atmosphere. These greenhouse gases lead to an increase of energy in the atmosphere which is equivalent to increasing temperatures.
The surface temperature of the northern hemisphere has rised by about 0.7 degree celsius in the last 150 years the same way the carbon dioxide emissions have been growing. 0.7 degree celsius seems a minor change but it is not:
- This value is a spatial average. Local temperature changes are much larger. Example: About 5 degrees temperature increase in some arctic regions.
- This value is a temporal average. Temperature variations are much higher without influence to the average. Examples: Extreme weather like droughts, flooding, heat waves (2003 in europe) occur more frequently in the last decade.
- For many processes and relations such a minor change of environmental temperatures has major impact.Example: Animals might extend their population areas. They migrate faster as their predators in regions without any predators -- an explosion like population increase might occur.