Leading doctors are backing legal action against UK government ministers on the grounds that they have not fulfilled their commitments to cutting carbon emissions in line with the Climate Change Act of 2008 and the Paris Agreement objective of limiting warming to 1.5?C or 'well below' 2?C.

In an open letter published by The BMJ, 18 health professionals, including The BMJ's Editor in Chief Dr Fiona Godlee, are supporting campaign group Plan B's legal challenge to force the government to revise its 2050 carbon target, saying it is inconsistent with the Paris Agreement temperature objective.

Former chief government scientist, Professor Sir David King, has also endorsed this approach.

The UK currently has a legally binding target to reduce emissions by 80 per cent by 2050, even though they must be brought down to net zero by that date to meet the country's international obligations.

"Climate change has serious implications for our health, wellbeing, livelihoods, and the structure of organised society," they write.

They point to direct effects resulting from rising temperatures and changes in the frequency and strength of storms, floods, droughts, and heat-waves -- as well as to less direct impacts, such as changes in crop yields, the burden and distribution of infectious disease, and climate-induced population displacement and violent conflict.

"Although many of these effects are already seen, their progression in the absence of climate change mitigation will greatly amplify existing global health challenges and inequalities," they warn.

Yet urgent and substantial climate change mitigation "will help protect human health from the worst of these effects, and a comprehensive and ambitious response to climate change could transform the health of the world's populations," they argue.

As a self-proclaimed 'climate leader' the UK government has a critical role to play in closing the 'emissions gap' -- the gap between the current global trajectory of greenhouse gas emissions and the actions necessary to limit warming to 1.5?C and 'well below' 2?C (and hence reduce the risks of disaster), they write. "We are therefore disturbed and concerned by the government's maintenance of a target despite awareness of its inadequacy."

And they urge the government "to show real leadership and revise the carbon target in line with the Paris Agreement (and on the basis of equity and the precautionary principle) as a matter of urgent and immediate priority."