How Much Climate Change Has Been Observed to Date?
• Globally, surface air temperatures increased by approximately 1oF during the 20th century. Some regions of the world have experienced much greater warming; Alaska and the Antarctic peninsula, for example, have warmed by approximately 4oF over the same time period. Other regions of the world, such as the oceans of the Southern Hemisphere and the interior of Antarctica, have not experienced warming. • The observed warming over the 20th century was accompanied by a 10% increase in precipitation in the Northern Hemisphere and an increase in global sea-level of 4-8 inches.
