Throughout history, the Earth has experienced cold and warm periods, known as ice ages and interglacial periods. In the past million years, these natural climate changes were due to periodic variations in the Earth’s orbit that affect the amount of sunlight received on the Earth's surface. So it is true that the planet’s climate is constantly changing. However scientists are now concerned that the natural fluctuation has been overtaken by a rapid human-induced warming that has serious implications for the stability of the climate on which much life on the planet depends. The UN IPCC is projecting increases of 1.4 to 5.8° C in globally averaged surface temperatures by the year 2100, as compared with 1990. This represents a rate of warming that is far greater than any that has occurred in the last 10,000 years - the period over which civilization has developed.
One degree
