Global Warming and the Hockey Stick graph:
The above plot shows the carbondioxid level in Earth's atmosphere over the last 400,000 years. Notice the drastic increase increase over the last roughly 100 years. This is one of the main pieces of evidence that scientists have accumulated to support the theory of global warming induced by human activities (mostly burning of fossil fuels). While at the beginning of the global warming 'scare' I was never a believer, I take this plot very serious and find it disturbing. One notices in particular that the local maxima of 300 ppm with a period of about 100,000 years have occurred naturally in the past, and that we live at a time when another maxima of around 300 ppm should be attained. However, the increase to 400 ppm in the last 100 years seems completely new in light of the past tendencies. So whereas we are probably just on the verge of a natural maximum and subsequent ice age, the human activity seems to be having tremendous influence on matters. Perhaps we actually need to not only stop using fossil fuels, but will have to figure out some way to reverse the effect.... One must however, still remember that there are large uncertainties involved in generating a plot like the one above, so we still need more and better studies to make sure.