The UK will slash its net greenhouse gas emissions to zero by 2050, Theresa May has vowed.
The legislation – which will be announced in parliament on Wednesday – will make the UK the first G7 country to set such a target into law.
May said the move would allow the UK “to be truly proud of our record in tackling climate change”.
“Now is the time to go further and faster to safeguard the environment for our children,” she said.
“This country led the world in innovation during the Industrial Revolution, and now we must lead the world to a cleaner, greener form of growth.”
The current target – which was set in 2008 – was to reduce emissions by 80% by 2050 against levels in the 1990s.
But a report by the Committee on Climate Change commissioned by the government last year said changing the target to net zero would improve public health and produce savings for the NHS by improving air quality and reducing noise pollution.
Director of the Energy and Climate Intelligence Unit Richard Black called the new target “probably the most important UK move on climate change since parliament brought in the Climate Change Act more than a decade ago”.
With just weeks to go until May is replaced in Downing Street, the move is likely to be seen as an attempt by the PM to secure her legacy, having failed to deliver Brexit.
It comes after chancellor Philip Hammond reportedly warned the prime minister that reducing the emissions target to net zero would cost more than £1 trillion and could lead to spending cuts for schools, police forces and the NHS.
Downing Street denied the claims, saying it would cost no more than the UK’s existing plans to reduce greenhouse gas emissions.
Meanwhile, energy secretary Greg Clark said the new target was “necessary and feasible”.
“Almost 400,000 people are already employed in the low-carbon sector and its supply chains across the country,” he said, adding that the government’s industrial strategy would allow the country to “reap the rewards” of clean growth and “create two million high quality jobs by 2030”.
The UK will also conduct further assessments within five years to make sure other countries are taking similar action to make sure UK industry does not face unfair competition, the government said.