'The reality is it's what you do, not what you say, that matters.'
Theresa May's announcement that the UK is to set a legally binding target to end its contribution to climate change by 2050 has been met with a mixed reaction.
The Government will lay out legislation in Parliament on Wednesday to set a new target to cut emissions to "net zero" by the middle of the century. But while some climate change figures welcomed the move, others gave a more cautious assessment.
Lord Deben, chairman of the Government's advisory Committee on Climate Change, praised the "major commitment" and said he was looking forward to cross-party consensus on the issue.
"This step will send a strong signal to other countries to follow suit - and will help to drive the global effort to tackle climate change required by the Paris Agreement," he said.
Dame Carolyn Fairbairn, director-general of business group the CBI, said UK companies were "squarely behind" the commitment and called it the "right response to the global climate crisis".
But she urged the Government to ensure the legislation was followed by long-term policies to support decarbonisation across the economy.
"Some sectors will need clear pathways to enable investment in low-carbon technologies, and it is vital that there is cross-Government coordination on the policies and regulation needed to deliver a clean future," she said.
Doug Parr, Greenpeace UK's chief scientist, said it was a "big moment" for the climate, but added there were "questions to be asked about (the) offsetting loophole", seemingly in reference to the plan's allowance for international carbon credits which allow the UK to pay to offset its emissions elsewhere in the world.
Craig Bennett, UK chief executive of Friends of the Earth, said Mrs May's premiership had been "characterised by chronic inaction on climate breakdown" and 2050 is "still too slow to address catastrophic climate change".
He said: "It is disappointing that the Government has ignored its climate advisers' recommendation to exclude carbon offsets - as well as caving into Treasury pressure to review the target in five years' time.
"Fiddling the figures would put a huge dent in our ability to avoid catastrophic climate change - and the Government's credibility for taking this issue seriously. Having declared a climate emergency, Parliament must act to close these loopholes.
"2050 is still too slow to address catastrophic climate change, the UK can and must go faster. The next prime minister must legislate to end our contribution to climate breakdown earlier, put carbon-cutting at the centre of policy-making and pull the plug on plans for more roads, runways and fracking. It's now time to build the carbon-free future that science requires and the public are so loudly demanding."
Gareth Redmond King, head of climate change at the environmental charity WWF, said the announcement was a "crucial first step".
He added: "If we want future generations to live on a viable planet where the mass extinctions we're witnessing halt, food security is ensured and coastal regions are safe, then Government must accelerate policies and commit resource to slashing emissions, heat our homes with clean energy and make climate action a priority across all departments."
He said the speed in developing innovative technologies such as solar panels and wind turbines in the past decade should provide hope the UK could go faster and reach net zero by 2045.
Meanwhile, shadow energy secretary Rebecca Long Bailey raised concerns over how the commitment would be put into practice.
"While this announcement is welcome in theory, in practice it comes from a Conservative government that is off track to meet existing climate targets, that has no plans for legislation or investment needed to cut emissions, and that has dismantled the UK renewable energy sector while pushing fracking," she said.
Extinction Rebellion, the protest group that brought parts of London to a standstill with demonstrations in April, said Mrs May's 2050 target was a "death sentence". "People are already dying and this will only get worse with far off dates," the group said.
"Were we to put our minds to it and do what is required to mobilise society to address the threat with the seriousness it deserves, the UK could embrace transformative change and decarbonise in years not decades.
"We welcome that the Prime Minister is finally talking about the emergency. This is a testament to the public pressure - including the more than 1,000 people willingly arrested for this cause - that is forcing politicians to confront the existential reality of the climate and ecological emergency. But it is not nearly enough."
Environment analyst Tom Burke said there was "quite a gap" emerging between announcements on climate change and the implementation of policies. He told BBC Breakfast: "The reality is it's what you do, not what you say, that matters.
"There's been quite a gap, in a way, emerging recently between what the Government has said it wants to do on climate change and the fact that the policies aren't in place to deliver on the existing budgets, let alone the carbon budgets we'll need if we're to meet this new commitment."
Brendan Montague is editor of The Ecologist. This report is based on copy provided by the Press Association.