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Average temperatures have only increased by 0·7°C. So why does it matter?

The temperature rise has led to many changes to the natural world:

  • The majority of the world's mountain glaciers are retreating and Arctic sea-ice appears to be both thinner and less widespread.
  • Global sea levels have risen 10-20cm over the past 100 years - a rate of about 2mm a year. This is faster than the rise over the last 5000 years (less than 1mm a year), but still slower than the average rise of 5mm a year predicted for the next 80 years. Most of this rise is caused because as the oceans get warmer, their water takes up more space (thermal expansion). Melting glaciers in the Andes, Himalayas, the Rockies and the Alps cause some of the rise. We don't yet know how much the polar regions are contributing to sea level rise.
  • Permafrost is thawing in Alaska, Western Siberia and other arctic regions.
  • The seasons are changing. Spring arrives earlier: bees and butterflies can now appear in late winter, and people have seen daffodils at Christmas.
  • Plant and animal ranges are shifting - fish are moving further north, the black kite and snow egret are expanding their ranges into the UK from southern Europe.
  • Some plant and animal populations are declining, such as the capercaillie, the snow bunting and various arctic flowers.

The Intergovernmental Panel on Climate Change (IPCC) predicts temperatures will rise between 1·5-5·8°C this century.

A 3°C rise in temperature will melt the Greenland ice sheet. It may take thousands of years to melt completely but if it does, global sea levels will rise by seven metres.

According to the IPCC, global sea level is likely to rise by 10-90cm over this century. Low-lying coasts will flood, affecting many human settlements, including some major cities. Some natural habitats will be lost.

Many areas will have more extremely hot weather, like the unprecedented European heatwave of 2003 which caused around 30,000 heat-related deaths. The UK is also predicted to see heavier rainfalls, with an increased risk of flooding.

There will be more ferocious tropical cyclones and more storm surges. A storm surge in Bangladesh killed 300,000 people in 1970 and further surges killed 200,000 people there in the 1980s.