Evidence

Further, a group of 17 national academies of science from around the world issued a statement endorsing the IPCC as the most reliable source of information on climate change and its latest conclusions.

In 2001 the IPCC released its third assessment report which shows stronger evidence that we do understand how the climate system works, and how human activity is changing it. This latest report provides a clear warning that the first signs of climate change impacts are occurring and that the scale of the risks posed by climate change are enormous.

The assessment finds that there is '"new and stronger evidence that most of the observed warming over the last 50 years is attributable to human activities." Not only this, but global warming is happening more quickly than previously thought. The IPCC gives the following evidence that climate change is happening now.

· The 1990's was most likely the warmest decade ever, and 1998 the warmest year.

· As the average global surface temperature has increased, snow cover and ice extent have decreased.

· Global average sea level has risen and the oceans are warming.

· Regional climate changes, particularly temperature increases, have already affected many physical and biological systems. These impacts include:

- Glacier shrinkage.
- Permafrost thawing.
- Later freezing and earlier break-up of ice on rivers and lakes.
- Lengthening of mid to high level growing seasons.
- Plant and animal range shifts.
- Declines of some plant and animal populations.
- Earlier flowering of trees, emergence of insects and egg-laying in birds.