Angela Merkel, Emmanuel Macron and other world leaders – but not, apparently, Theresa May – will try to convince Donald Trump that the US should remain part of the international fight against climate change when they meet at the G7 summit.

The Prime Minister has been accused of having a “pact of silence” with the Republican billionaire over his description of climate change as a “hoax”, his plan to withdraw the US from the landmark Paris Agreement and pledge to reinvigorate the US coal industry.

A petition by Greenpeace urging Ms May to “use your influence to save the Paris climate deal” has attracted more than 155,000 signatures.

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Speaking at a meeting of about 30 nations in Berlin before meeting Mr Trump at the G7 summit on 26 and 27 May, the German Chancellor said dealing with climate change must be an international effort.

“We are responsible for each other,” Ms Merkel said. “I am trying to convince doubters. There is still work to do.”

Mr Macron, the newly elected French president, will also attempt to convince Mr Trump to keep the US within the terms of the Paris Agreement, a senior French official told Reuters.

“What’s at stake is to be firm on the Paris accord,” the diplomat said, adding that Mr Macron would put his case to Mr Trump in person.

“We don’t want the US to pull out because it would be a very bad signal and lead others to pull out.”

Ms May has sent mixed messages on climate change. One of her first acts as Prime Minister was to close the dedicated climate change department and move its responsibilities into the new Department of Business, Energy and Industrial Strategy.

The Government has persistently failed on attempts to come up with an effective plan to reduce air pollution to within minimum safety standards, and its Emissions Reduction Plan – the key policy setting out how the UK will cut its greenhouse gases – is long overdue.

However it also ratified the Paris Agreement and approved the UK’s “Fifth Carbon Budget”, which sets tough emissions reduction targets.

There has been speculation that Ms May is keen to have Mr Trump as a political ally, particularly because of the talks with the European Union over Brexit. With the US on its side, the UK might be in a stronger negotiating position than if this were not the case.

This could explain her reluctance to expend political capital on climate change, particularly if she thinks it would only aggravate Mr Trump.

Shape Created with Sketch. Donald Trump's first 100 days: in cartoons Show all 33 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. Donald Trump's first 100 days: in cartoons 1/33 Donald Trump's first 100 days in office were marred by a string of scandals, many of which caught the eye of the Independent's cartoonists 2/33 Trump's first 100 days have seen him aggressively ramp up tensions with his nuclear rivals in North Korea 3/33 Mr Trump has warned of a "major, major conflict" with the pariah nation lead by Kim Jong Un 4/33 Mr Trump dropped the "mother of all bombs" on alleged ISIS-linked militants in Afghanistan, amid an escalation of US military intervention around the globe 5/33 Mr Trump has been accused of falling short of the standards set by his predecessors in the Oval Office, including Franklin D Roosevelt 6/33 The tycoon's ascension to the White House came at a time when the balance of power is shifting away from Western nations like those in the G7 group 7/33 Western politicians, including the British Conservative party, have been accused of falling in line behind Mr Trump's proposals 8/33 Brexit is seen to have weakened Britain, reducing still further any political will to resist American leadership 9/33 Mr Trump's leadership has been marked by sudden and unexpected shifts in global policy 10/33 Trump's controversial missile strike on Syria, which killed several citizens, was seen by some analysts as an attempt to distract from his policy elsewhere 11/33 The President has also spent a large majority of his weekends golfing, rather than attending to matters of state 12/33 Though free of gaffes, a visit from Chinese president Xi Jinping spotlighted trade tensions between the two states 13/33 One major and unexpected setback came when Mr Trump's Healthcare Bill was struck down by members of his own party 14/33 Mr Trump has been a figure of fun in the media, with his approval at record lows 15/33 A string of revelations about Mr Trump's financial indiscretions did not mar his surge to the White House 16/33 Outgoing President Barack Obama was accused of wiretapping Trump Tower by his successor in America's highest office 17/33 The alleged involvement of Russian intelligence operatives in securing Mr Trump the presidency prompted harsh criticism 18/33 The explosive resignation of Security Adviser Michael Flynn, who lied about his links to the Russian ambassador, was just one scandal to hit the President 19/33 Many scandals, such as the accusation Barack Obama was implicated in phone-hacking, first broke on Mr Trump's Twitter feed 20/33 Donald Trump's election provoked mass protests in the UK, with millions signing a petition to ban him from the country 21/33 Donald Trump cited a non-existent terror attack in Sweden during a campaign rally 22/33 Donald Trump stands accused of stoking regional tensions in Eastern Asia 23/33 North Korea has launched a number of failed nuclear tests since Mr Trump took power 24/33 Theresa May formally rejected the petition calling for Mr Trump to be banned from the UK 25/33 When Mr Trump's initial so-called Muslim ban was struck down by a federal justice, the President mocked the 69-year-old as a "ridiculous", "so-called judge" 26/33 A week after his inauguration, Theresa May met with Mr Trump at the White House 27/33 Donald Trump's first days in office were marked by a hasty attempt to follow through on many of his campaign promises, including the so-called Muslim ban 28/33 Donald Trump's decision to ban citizens of many majority-Muslim countries from the US sparked mass protests 29/33 Revelations about Donald Trump's sexual improprieties were not enough to keep him from being elected President 30/33 British PM Theresa May was criticised by many in the press for cosying up to the new President 31/33 One of Mr Trump's top aides, Kelly Anne Conway, was mocked for describing mistruths as "alternative facts" 32/33 British PM Theresa May was quick to demonstrate that her political aims did not hugely differ from Mr Trump's 33/33 Donald Trump's inauguration, on 20 January 2017, sparked protests both at home and abroad 1/33 Donald Trump's first 100 days in office were marred by a string of scandals, many of which caught the eye of the Independent's cartoonists 2/33 Trump's first 100 days have seen him aggressively ramp up tensions with his nuclear rivals in North Korea 3/33 Mr Trump has warned of a "major, major conflict" with the pariah nation lead by Kim Jong Un 4/33 Mr Trump dropped the "mother of all bombs" on alleged ISIS-linked militants in Afghanistan, amid an escalation of US military intervention around the globe 5/33 Mr Trump has been accused of falling short of the standards set by his predecessors in the Oval Office, including Franklin D Roosevelt 6/33 The tycoon's ascension to the White House came at a time when the balance of power is shifting away from Western nations like those in the G7 group 7/33 Western politicians, including the British Conservative party, have been accused of falling in line behind Mr Trump's proposals 8/33 Brexit is seen to have weakened Britain, reducing still further any political will to resist American leadership 9/33 Mr Trump's leadership has been marked by sudden and unexpected shifts in global policy 10/33 Trump's controversial missile strike on Syria, which killed several citizens, was seen by some analysts as an attempt to distract from his policy elsewhere 11/33 The President has also spent a large majority of his weekends golfing, rather than attending to matters of state 12/33 Though free of gaffes, a visit from Chinese president Xi Jinping spotlighted trade tensions between the two states 13/33 One major and unexpected setback came when Mr Trump's Healthcare Bill was struck down by members of his own party 14/33 Mr Trump has been a figure of fun in the media, with his approval at record lows 15/33 A string of revelations about Mr Trump's financial indiscretions did not mar his surge to the White House 16/33 Outgoing President Barack Obama was accused of wiretapping Trump Tower by his successor in America's highest office 17/33 The alleged involvement of Russian intelligence operatives in securing Mr Trump the presidency prompted harsh criticism 18/33 The explosive resignation of Security Adviser Michael Flynn, who lied about his links to the Russian ambassador, was just one scandal to hit the President 19/33 Many scandals, such as the accusation Barack Obama was implicated in phone-hacking, first broke on Mr Trump's Twitter feed 20/33 Donald Trump's election provoked mass protests in the UK, with millions signing a petition to ban him from the country 21/33 Donald Trump cited a non-existent terror attack in Sweden during a campaign rally 22/33 Donald Trump stands accused of stoking regional tensions in Eastern Asia 23/33 North Korea has launched a number of failed nuclear tests since Mr Trump took power 24/33 Theresa May formally rejected the petition calling for Mr Trump to be banned from the UK 25/33 When Mr Trump's initial so-called Muslim ban was struck down by a federal justice, the President mocked the 69-year-old as a "ridiculous", "so-called judge" 26/33 A week after his inauguration, Theresa May met with Mr Trump at the White House 27/33 Donald Trump's first days in office were marked by a hasty attempt to follow through on many of his campaign promises, including the so-called Muslim ban 28/33 Donald Trump's decision to ban citizens of many majority-Muslim countries from the US sparked mass protests 29/33 Revelations about Donald Trump's sexual improprieties were not enough to keep him from being elected President 30/33 British PM Theresa May was criticised by many in the press for cosying up to the new President 31/33 One of Mr Trump's top aides, Kelly Anne Conway, was mocked for describing mistruths as "alternative facts" 32/33 British PM Theresa May was quick to demonstrate that her political aims did not hugely differ from Mr Trump's 33/33 Donald Trump's inauguration, on 20 January 2017, sparked protests both at home and abroad

But the US President seemed happy enough to receive advice from Pope Francis during his visit to the Vatican.

Francis gave Mr Trump a signed copy of a message of peace, called “Nonviolence: A Style of Politics for Peace”, and a copy of his 2015 encyclical letter on the need to protect the environment from the effects of climate change.

“Well, I’ll be reading them,” Mr Trump said.

The Sierra Club, the largest grassroots environmental group in the US with about two million members, noted the Pope had been at the forefront of calls for action on climate change for years.

Speaking ahead of the meeting with Mr Trump, John Coequyt, the group’s global climate policy director, said the Pope’s “sentiments and actions have been echoed by nearly every other world leader around the globe, yet Trump is heading into [their] meeting as the only climate-denying world leader”.

“Trump stands on one side of this issue, while the Pope, a large majority of the American public, business leaders and the global community stand on the other,” he added.

“If one thing is already clear from this meeting, Donald Trump’s denial of the climate crisis has isolated him from the rest of the world and ceded US leadership on the most pressing issue of our lives.”

The Trump administration had been due to decide whether to remain a signatory of the Paris Agreement before the G7 meeting, but two internal meetings to discuss the issue were postponed without explanation.

In November, Fiji is due to be the official host of talks about climate change involving about 200 countries, held in Bonn, Germany, for logistical reasons.

Frank Bainimarama, Fiji’s Prime Minister, suggested everyone was worried about what Mr Trump would ultimately decide to do.

“We have an elephant in the room,” he said. “That is uncertainty over the position of the United States.”

Downing Street did not immediately respond to a request for comment.

Reuters contributed to this report