This graph shows global temperatures going as far back as 400,000 years.
Monday, November 2, 2015
Many people are focused on the temperature change that they have experienced in their lifetime, and do not take into consideration that, maybe, the earth's rising temperature is normal? If you go back as far as the Paleozoic and Mesozoic times, scientists have come to the conclusion that the earth was 2-6 degrees celsius hotter than it is now. On the other side of the spectrum, during the ice ages of the Pliocene and Pleistocene times, the earth was 2-3 degrees celsius cooler than now.
The fluctuations in the Earth's temperature are said to be caused by the Milankovitch cycles. These are long term variations in the Earth's orbit, which causes climate change over the period of hundreds of thousands of years. There are three different ways that the Earth's orbit can change: eccentricity, precession, and tilt. Because of these, the Earth's orbit changes and ice ages can occur.