What evidence is available that shows that Global Warming is real and that it is being caused by man-made greenhouse gases?
Since 2001, no climate scientists have expressed skepticism that Global Warming, of the magnitude described by the IPCC (Intergovernmental Panel on Climate Change), has occurred.
From Wikipedia http://en.wikipedia.org/wiki/List_of_scientists_opposing_global_warming_consensus
As you can see there is no doubt that the Earth has been warming up over the last decades. Records of temperature were started in seventeenth century England. Instrumental records were not started until the nineteenth century. From that moment on, reliable temperature records have been kept, and more modern satellites have provided excellent climate data. This data has proved that the Earth has warmed up about 0.6 °C during the 20th century. And furthermore, with the help of data taken from tree rings, ice cores and other sources, scientists have been able to construct a quite accurate picture of how the climate of the Earth looked like in the past. And by the past I mean thousands of years ago.
It is also a known fact that since the industrial revolution the concentration of CO2 in the atmosphere has increased significantly. Measurements from the Mauna Loa observatory in Hawaii have shown that the concentration of CO2 in the atmosphere has already risen to its historical maximum. The maximum concentration of CO2 ever found in ice cores is about 300ppm (parts per million). In 2005 the concentration of CO2 in the atmosphere was about 375ppm. Since CO2 is a greenhouse gas, it will increase global temperature. Although there is some doubt about how much CO2 affects climate, due to the complexity of the earth’s climate system.
