Britain must abandon using almost all fossil fuels to produce power in 20 years' time, the government's climate change watchdog will warn today.

The independent Climate Change Committee will publish its advice to the government that the UK should set a 2050 target of cutting all greenhouse gas emissions by at least 80% - including the emissions from aviation and transport, which were previously excluded.

Because it is unlikely that emissions from aviation and shipping will be cut so dramatically, other sectors, particularly power generation, would have to reduce emissions by much more, with big increases in energy efficiency, wind and tide power, and probably new nuclear generators, Lord Turner of Ecchinswell, the committee chairman, told the Guardian.