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. Crucially, that action will have to be taken within Obama's first administration, he added.


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."