Forests around the world will need to be expanded by 5-15% to limit global temperature rises to 2C.
And crop yields must rise by 40-60%.
These are just two predictions for 2050 of an online tool developed by the government to consider options for cutting carbon emissions.
The Global Calculator uses data reviewed by international experts to look at scenarios for meeting the 2C target, which scientists say is needed to avoid dangerous climate change.
Led by the Department of Energy and Climate Change (Decc), the model of the world's energy, land and food systems suggests living standards can be maintained, but only by making sweeping changes to agriculture, transport, food and fuel.
There would need be hundreds of million electric cars on the road by 2050, and the amount of CO2 emitted per unit of electricity would need to fall by at least 90%.