Effects of Climate Change

A rise in mean global temperature does not simply make everywhere a little warmer. It changes the whole climate system, and the effects vary from place to place.Rainfall patterns: warmer air holds more water vapour (about 7% more for each 1 °C), so there is more evaporation and heavier rainfall in some regions. Other regions, such as the Mediterranean and parts of Africa and Australia, are becoming drier, with more frequent droughts, water shortages and wildfires.Extreme weather: heatwaves are becoming more frequent and intense, and storms such as hurricanes may carry more energy and rain because they draw energy from warmer seas.Seasonal changes: in temperate regions spring arrives earlier and autumn later, so the growing season is longer. Winters are milder, with fewer frosts.Ice and snow: sea ice, glaciers and snow cover are shrinking. This causes a positive feedback: ice reflects much of the Sun's radiation, but darker ocean or land absorbs more, so melting leads to further warming. The Arctic is warming around three to four times faster than the global average.These changes affect people as well as wildlife. Crop yields may rise in some cooler regions with a longer growing season, but fall in regions affected by drought and heat stress, threatening food security. Water supplies that depend on melting glaciers and snow may fail.The following lessons look at specific effects: the risk of flooding, the effect of temperature on organisms and changes in the distribution of species.