Warming is now expected to go up between 1.4 and 5.8 degree C between 1990 and 2100. The 1990s was the warmest decade, and 1998 the warmest year since 1861, when instruments were first used to record temperatures. The global average surface temperature is projected to increase by 1.4 to 5.8 degree C between 1990 and 2100. This is far more than the projection in the 1995 assessment of a 1 to 3.5 degree C temperature rise. There was a widespread retreat of mountain glaciers outside the polar regions during the 20 th century.
More decrease is projected for both snow cover and sea-ice extent.
The global average sea level rose between 0.1 and 0.2 metres during the 20 th century, while global ocean heat content has gone up since the late 1950s, the period for which data on sub-surface ocean temperatures have been available. There is a projected rise of another 0.09 to 0.88 metres between 1990 and 2100. In parts of Asia and Africa, the frequency and intensity of droughts have increased in recent years. Human activities will continue to change the climate in the 21 st century, with CO2 emissions from fossil fuel burning as the dominant influence. To stabilise CO2 concentrations in the atmosphere at 450 ppm, the IPCC report said that human-induced emissions will have to drop below 1990 levels within a few decades.