Christian environmental organisation A Rocha UK has questioned how realistic the UK Government's emission reduction target is.
On Friday, Prime Minister Boris Johnson announced a new target to cut the UK's emissions by at least 68 per cent by 2030 as part of global efforts to curb climate change.
He said the "ambitious" target in the new climate plan - or nationally determined contribution (NDC) - under the Paris Agreement would see the UK cutting emissions at the fastest rate of any major economy so far.
While Andy Lester, conservation director at A Rocha UK, said the government is taking a positive step, he's not getting his hopes up.
"They've announced some schemes over the last few days, including £1bn for further insulation to homes in the UK. But in the same breath, they are investing £120bn in projects like HS2 and road building.
"As a scientist, I can't make the figures add up. If you are investing in new transport provision and new roads, and investing a fraction of that in things like insulation, and there's no really solid figures yet on green energy provision, you've got to ask the question, 'well, how are you going to achieve that by 2030?'"
The 2030 target to cut greenhouse gases by at least 68 per cent on 1990 levels goes further than previous targets under domestic climate law, which required a 61 per cent reduction over that time.
And it is significantly higher than the UK's target to cut emissions by 53 per cent, as its contribution to the European Union's existing climate plan under the Paris deal - though the bloc is also expected to raise its ambition.
The UK, which is set to host United Nations Cop26 climate talks in Glasgow next year after the conference was delayed by the pandemic, is setting out its own national plan for the first time due to Brexit.
Lester said he's approaching the pledge with caution.
"I won't be drawn one way or the other unless we see some really clear metrics about how they plan to deliver that figure," he said. "At the moment they're behind their pledges. We're not on for 53 per cent by 2030 at present. So if we're not even on for the 53 per cent, how are we going to get to the 68?"
Under the Paris Agreement, countries have committed to keep global warming to "well below" 2C above pre-industrial levels, and pursue efforts to limit it to 1.5C, seen as the threshold beyond which the worst impacts of climate change will be felt.
To meet the 1.5C target, the world's carbon emissions must fall to net zero by 2050, with significant cuts in pollution and any remaining emissions offset by planting trees or using technology to capture carbon.
The UK has a legally binding target to cut emissions to net zero by 2050 and other countries have committed to or plan similar long term goals.
Lester said it's vital the issue is taken seriously and is tackled with a global effort.
"If we don't, there will be global food shortages. There will be global water shortages. There will be extinction of many of the familiar birds and plants and insects that we need for our food, as well as the ones that we love. So we are facing an existential crisis. They will have huge impacts on the population of many countries, not just in the developing world."
The UK announcement comes ahead of a climate summit it is co-hosting with the United Nations and France on December 12 to mark five years since the Paris deal was agreed.
Listen to Premier's interview with Andy Lester here: