Alok Sharma has been appointed by the Prime Minister to be the full-time president of the UN Cop26 climate conference, with Kwasi Kwarteng promoted to Business Secretary.

The Cop26, due to be held in Glasgow in November after being postponed by 12 months due to the coronavirus pandemic, will be the largest summit the UK has ever hosted, bringing together representatives and world leaders from nearly 200 countries.

Boris Johnson has decided that Mr Sharma, who has been leading on the preparations since February 2020, will make the conference his sole focus rather than combine it with his secretary of state duties.

Mr Sharma will remain a full member of Cabinet, with the Cop26 presidency affording him a ministerial role in the Cabinet Office.

Downing Street officials said Mr Johnson sees a successful summit in November as being critical if the UK is to meet the emission-reducing objectives set out by the Paris Agreement.

The Prime Minister has recently committed to reducing emissions by at least 68% by 2030 and is looking for buy-in from other nations to take on similar ambitious targets.

Mr Sharma said: “The biggest challenge of our time is climate change and we need to work together to deliver a cleaner, greener world and build back better for present and future generations.

“Through the UK’s presidency of Cop26 we have a unique opportunity, working with friends and partners around the world, to deliver on this goal.

“Given the vital importance of tackling climate change, I am delighted to have been asked by the Prime Minister to dedicate all my energies to this urgent task.”

As well as his president duties, Mr Sharma will also chair the Climate Action Implementation Committee to coordinate Government action towards net-zero carbon emissions by 2050 in the run-up to the conference in 10 months’ time, No 10 said.

Mr Kwarteng will step up from his role as a minister in the Department for Business, Energy and Industrial Strategy to take on the top job of Business Secretary.

Former international development secretary Anne-Marie Trevelyan will take over his role as minister of state. She had previously lost her Cabinet position last year after the Department for International Development was folded into the Foreign Office.

Ms Trevelyan will also continue in her role as UK’s international champion on adaptation and resilience for the Cop26 presidency, supporting countries vulnerable to climate change to adapt to its impacts and build resilience, No 10 confirmed.

Labour’s shadow business secretary Ed Miliband said: “It’s welcome that Alok Sharma is now doing the Cop presidency as a full-time role.

“It’s absolutely crucial that the full political, diplomatic and strategic resources of government are now directed to the most ambitious outcome at Glasgow, which is a 1.5 degree deal.”