While the earth has previously had both cold and warm periods, these were natural climate variations due to changes in the Earth’s orbit that that affected the amount of sunlight received on the surface. However, simulations using computer based climate models confirm that global warming in the past 50 years was mainly caused by human activities that have increased atmospheric concentrations of greenhouse gasses, and the current rate can not be attributed to variations in the orbit of the earth. Climate models driven by greenhouse gas emission scenarios indicate that over the next century a global warming of 1.4 – 5.8 degrees C can occur. History has shown us that even a warming of 1 – 2 degrees can have dramatic consequences- even the 0.6 degree warming in the past 100 years to the year 2000 has been associated with increasing heat waves and floods, coral bleaching, retreat of glaciers and ice sheets and more intense droughts.
One degree
