Four years to Save the Earth.

Barack Obama has only four years to save the world. That is the stark assessment of Nasa scientist and leading climate expert Jim Hansen who last week warned only urgent action by the new president could halt the devastating climate change that now threatens Earth.

Soaring carbon emissions are already causing ice-cap melting and threaten to trigger global flooding, widespread species loss and major disruptions of weather patterns in the near future. "We cannot afford to put off change any longer," said Hansen. "We have to get on a new path within this new administration. We have only four years left for Obama to set an example to the rest of the world. America must take the lead."

Henning Steinfeld, Chief of FAO’s Livestock Information and Policy Branch and senior author of the report: “Livestock are one of the most significant contributors to today’s most serious environmental problems. Urgent action is required to remedy the situation.”

Hansen said feedbacks in the climate system are already accelerating ice melt and are threatening to lead to the collapse of ice sheets. Sea-level rises will therefore be far greater - a claim backed last week by a group of British, Danish and Finnish scientists who said studies of past variations in climate indicate that a far more likely figure for sea-level rise will be about 1.4 metres, enough to cause devastating flooding of many of the world's major cities and of low-lying areas of Holland, Bangladesh and other nations.

Stretches of Britain's coastline are doomed and plans will soon have to be drawn up to evacuate people from the most threatened areas, the new head of the Environment Agency warns today.