Climate changeClimate change refers to any change in climate over time, whether due to natural variability or as a result of human activity (IPCC).
Climate refers to the average weather experienced over a long period. This includes temperature, wind and precipitation patterns. The climate of the Earth is not static but has changed many times of the history of our planet in response to a variety of natural causes.
For the past 30 years the Earth has been warming at a remarkably rapid rate of approximately 0.2°C per decade and is now reaching and passing through the warmest levels seen in the last 12 000 years (NASA 25.9.2006). Year 2005 was the warmest year since the late 1800s. The five warmest years during the past 100 years have all occurred recently (the warmest years being 2005, 1998, 2002, 2003, 2006) (NASA 8.2.2007 ).
Current warming seems to be occurring nearly everywhere. The warming is largest at high latitudes in the Northern Hemisphere and it is larger over land than over ocean areas. In Finland annual mean temperatures have increased about 0.7°C during the past century. Greatest warming has happened in the spring and less in summer and autumn (Finnish Meteorological Institute in Finnish). Climate changes are being experienced particularly extensively in the Arctic. Arctic average temperature has risen at almost twice the rate as the rest of the world in the recent decades (Finnish Meteorological Institute Corell 2005 ACIA).