Leading climate scientists have called for Theresa May to make her "legacy" a target to cut greenhouse gases to zero by 2050.
A group of experts have written to the prime minister calling for her to enshrine a target for "net zero" emissions in national law.
Experts claim the target is necessary to avoid dangerous climate change.
The government said the UK already leads the world in tackling global warming.
In their letter, the scientists said the evidence was "unequivocal" that avoiding dangerous climate change means eliminating or offsetting all carbon emissions - not just reducing them.
Among the signatories are emeritus professor Joanna Haigh from Imperial College London, Myles Allen from Oxford University, Sir Brian Hoskins, who chairs the Grantham Institute on Climate Change, and Professor Dame Julia Slingo, former chief scientist at the Met Office.
They said Mrs May could make "a powerful statement of global leadership", which would compare to Margaret Thatcher's intervention 30 years ago when she became the first leader of a major nation to call for a United Nations climate change treaty.
"To do so would be an act of global importance for future generations, and a worthy legacy," they said.
The current target written into law is to reduce greenhouse gases by 80% by 2050.
Their letter comes after the government's independent climate advisors, the Committee on Climate Change, urged ministers to set a new legal target for a 100% cut in all greenhouse gases by the middle of the century as soon as possible.
Meeting this target would mean stopping all emissions from electricity generation, transport and heating, while offsetting pollution from areas like aviation using measures to capture carbon, such as planting trees, the committee said.
A government spokesman said: "We already lead the world in tackling climate change, being the first country to introduce long-term legally-binding carbon reduction targets and cutting emissions further than all other G20 countries."
The spokesman said the government will respond to the Committee on Climate Change's zero-emissions recommendation "in a timeframe which reflects the urgency of the issue".