The Facts About Climate Change

How has the climate changed?

Average global surface temperatures have increased by 0.6°C over the 20th century. The ten hottest years on record have all occurred since the beginning of the 1990s. Much of the observed rise in sea-level (10 - 20 cm) during the 20th century may be related to this increase in global mean temperatures.

Climate Change Facts

The consensus view of the International Panel on Climate Change (IPPC) and more than 2,000 reputable scientists from across the world is that most of the warming seen since the middle of the last century is due to human activities. Over the last 200 years, the amount of carbon dioxide in the atmosphere – the major gas that causes climate change – has increased by 30 per cent. This and other gases stop some of the Earth’s radiation from escaping to space (rather like a greenhouse) and the result is that the Earth warms up. This is mainly due to the burning of coal, gas and oil.

Scientifc paper from the U.S Geological Survey - fact!

Pleistocene reduction of polar ice caps: Evidence from Cariaco Basin marine sediments

Sea level is projected to rise between 13 and 94 cm over the next 100 yr due to continued climate warming. The sea-level projections assume that polar ice sheets will remain stable or even increase on time scales of centuries, but controversial geologic evidence suggests that current polar ice sheets have been eliminated or greatly reduced during previous Pleistocene interglacials indicating that modern polar ice sheets have become unstable within the natural range of interglacial climates. Sea level may have been more than 20 m higher than today during a presumably very warm interglacial about 400 ka during marine isotope stage 11. Because of the implications for future sea level rise, additional study of the conflicting evidence for warmer conditions and higher sea level during marine isotope stage 11 is needed. Here we present microfossil and isotopic data from marine sediments of the Cariaco Basin supporting the interpretation that global sea level was 10–20 m higher than today during marine isotope stage 11. The increased sea level requires reduction in modern polar ice sheets and is consistent with the interpretation that the West Antarctic ice sheet and the Greenland ice sheet were absent or greatly reduced during marine isotope stage 11. Our results show a warm marine isotope stage 11 interglacial climate with sea level as high as or above modern sea level that lasted for 25 to 30 k.y. Variations in Earth's orbit around the sun (Milankovitch cycles) are considered to be a primary external force driving glacial-interglacial cycles. Current and marine isotope stage 11 Milankovitch forcing are very similar, suggesting that the present interglacial (Holocene) that began ca. 10 ka will continue for another 15 to 20 k.y. Therefore any anthropogenic climate warming will accelerate the natural process toward reduction in polar ice sheets. The potential for increased rates of sea level rise related to polar ice sheet decay should be considered as a potential natural hazard on centennial time scales.

. (R Poore & H Dowsett-U.S. Geological Survey, National Center 926, Reston, Virginia 20192, USA )

Since 1979, the size of the summer polar ice cap has shrunk more than 20 percent. (Illustration from NASA)

Average temperatures in the Arctic region are rising twice as fast as they are elsewhere in the world. Arctic ice is getting thinner, melting and rupturing. For example, the largest single block of ice in the Arctic, the Ward Hunt Ice Shelf, had been around for 3,000 years before it started cracking in 2000. Within two years it had split all the way through and is now breaking into pieces.

The polar ice cap as a whole is shrinking. Images from NASA satellites show that the area of permanent ice cover is contracting at a rate of 9 percent each decade. If this trend continues, summers in the Arctic could become ice-free by the end of the century.