The threat to human health from climate change is so great it could “undermine the last fifty years of gains in development and global health”.

That’s according to a major new study published in UK medical journal The Lancet.

The 2015 Lancet Commission on Health and Climate Change – which was composed of leading medics and academics – published a report which shows the direct health impacts of climate change come from the increasing frequency and intensity of extreme weather events, especially heat waves, floods, droughts and storms.

Indirect impacts come from changes in infectious disease patterns, air pollution, food insecurity and malnutrition, involuntary migration, displacement and conflicts.

The potentially catastrophic risk to human health posed by such effects has been underestimated.

The scientists added, while the technologies and finance required to address the problem can be made available, global political will to put them in place is lacking.

Commission co-Chair Professor Hugh Montgomery, director of the UCL Institute for Human Health and Performance said: “Climate Change is a medical emergency.

“It thus demands an emergency response, using the technologies available right now.

“Under such circumstances, no doctor would consider a series of annual case discussions and aspirations adequate, yet this is exactly how the global response to climate change is proceeding.”

Green campaigners welcomed the findings. Friends of the Earth’s head of policy Mike Childs said: “When health professionals shout ‘emergency’, politicians everywhere should listen.

“Already tens of thousands of lives are lost in the UK every year because of foot-dragging on climate change – radical action is urgently required to avoid catastrophe.

“The Government must end its cheer-leading for fossil fuels by stopping fracking and make the UK a world leader in energy efficiency and renewable power.”

The Commission report also shows responses to ease and adapt to climate change can have health benefits – from cutting air pollution to improving diet. It concludes that efforts to tackle it represent one of the greatest opportunities to improve global health this century.