Energy and Climate Change Secretary Amber Rudd has warned that all countries will need to make compromises as the high level part of crucial United Nations climate talks get under way.
Ministers from around the world are starting work on securing a new global climate deal at the talks in Paris after negotiators agreed a draft of the agreement, which aims to curb temperature rises and avoid dangerous climate change, over the weekend.
Ms Rudd has been given the role of chairing a group with Gambia's environment minister Pa Ousman Jarju on increasing the action countries will take to curb emissions before 2020, when the Paris deal would kick in.
But the Energy Secretary and the UK Government have faced criticism domestically for curbing measures to cut emissions including subsidies for renewables and energy efficiency, and the UK is likely to miss its EU 2020 targets for renewable energy.
The mood at the talks appears reasonably positive, although progress is slow and major sticking points remain on key issues such as the long-term goal for emissions reductions to avoid dangerous climate change and finance for poor countries to help them cope with global warming.
But observers say a deal can be done, with environmental consultants E3G suggesting that at the midpoint of the two-week talks, the negotiations are in the upper half of a "comme ci, comme ca" scenario that would see modest progress with guarantees on finance.
The organisation said there was still some prospect of a "Va Va Voom" outcome which would cement a new enduring regime on climate change.
The president of the "COP21" talks, French foreign minister Laurent Fabius, has brought the negotiations together under the so-called "Paris Committee" to make progress and facilitate compromises between the 195 countries negotiating the agreement.
Groups led by ministers will cover areas including implementing support for countries to tackle climate change, how to differentiate between rich and poor countries in the action they will take, and the ambition of the treaty including a long-term goal to cut emissions and periodically reviewing progress.
Ms Rudd said: "I am hopeful that we can get a deal, but I am not complacent.
"As one of eight ministers from around the world asked by the COP 21 Presidency to help facilitate the deal, I am clear that there is a huge amount of work to get through.
"Compromises and some hard decisions will need to be made, by all of us."
The French have set a tough timetable, wanting a final draft of the deal by Thursday - but experience from previous negotiations suggests the talks will overrun their official finish on Friday.
Ahead of the high-level segment of the talks, WWF UK's chief executive David Nussbaum urged Ms Rudd to show leadership, in solidarity with those countries already affected by climate change.
He said: "Now ministers have arrived in Paris, we enter the final straight. There is still much to do and the stakes are high.
"We need a fair, ambitious and transformational deal by Friday.
"The negotiations over the last week in Paris reflect the combined will of nearly 200 countries. At the moment, the text still includes the varying preferences of all the countries.
"In the coming days, ministers must build consensus on the remaining sticky issues.
"But as things stand, the Prime Minster was right in his opening speech here in Paris: This is doable."