The average global temperature has risen by more than 0.5°C during the past one and a half centuries. The global warming has caused climate change, with the climate becoming hotter in some places while in other places have become cooler and are getting more precipitation. The frequency of extreme phenomena of climate - hurricanes, draughts, heavy rains and floods etc. has grown. The global warming has become a worldwide environmental problem, but there have been been vast differences of opinion of the role of human activity as one of the main the cause of the process among scientists. Climate is an extremely complex, non-linear chaotic system with thousands of variables and influencers. The past and the future of the world climate has mainly been determined by astronomical factors and they will continue to do so also in the future. The Eesti Post souvenir sheet features an Antarctic glacier. The issue is dedicated to the protection of polar areas and glaciers and will mark the International Polar Year 2007-2009.