Since the last Ice Age, Earth's temperature has warmed by 4 to 7 degrees centigrade. Since 1880 it has jumped by 1.2 degrees centigrade. This accelerated global warming has had a big impact. The planet is heating up because of a massive rise in consumption of energy mostly generated by fossil fuels. Scientists monitor the planet's temperature daily and, while Antarctic ice cores show that over the last 800,000 years C02 levels remained constant, they have risen dramatically since 1950.