International Polar Year glossary

Global warming An increase in average global temperatures caused by natural events and human activities Greenhouse effect The warming process of the earth, where some of the sun’s energy is trapped by greenhouse gases (such as carbon dioxide, methane, water vapour and fluorocarbons) rather than being reflected back to space. This may be the result of natural events such as volcanic action, and is enhanced by human actions such as deforestation and burning of fossil fuels Iceberg A huge piece of floating ice that has broken off from a glacier or ice shelf, most of which is below the water Ice sheet A large area of ice that covers the land Ice shelf The ice floating in the sea at the edge of an ice sheet Polar regions Those areas inside the arctic or Antarctic Circle defined by latitude 66° 33´ north or south