Professor Stephen Schneider, climatologist at Stanford University points to the "inertia" in the Earth's climate system causing a lag between the greenhouse gases already in the atmosphere and the time it takes to make a corresponding warming of the oceans.

There may already be enough greenhouse gas in the atmosphere to ensure that in years to come polar bears at the N Pole and Penguins at the S Pole will be unable to make their seasonal migrations on pack ice in pursuit of food. The extinction time bomb may already be ticking.

Bill Hare of the Potsdam Institute for Climate Impact Research (Germany) has predicted a number of damaging effects on biodiversity linked to the level of temperature rise. Around 2°C above pre-industrial levels these effects include...

• "Bleaching" of coral reefs - the visual result of animals being forced out by high temperatures and the reef dying.
• Mediterranean regions will be hit by more forest fires and insect pests.
• The Fynbos in South Africa - the richest floral ecosystem on Earth will start to lose its species.
• The broadleaved forests of China will start to die.

At around 3°C above pre-industrial temperatures which may occur around the year 2070 the effects would be catastrophic with species extinction commonplace.