The UK looks set to miss a key renewable energy target, campaigners have warned, in the latest sign that the Government is backsliding on the fight against global warming.

As Angela Merkel prepares to lead attempts to take climate science denier Donald Trump to task at the forthcoming G20 summit in Germany, Whitehall officials quietly published a report revealing that Britain is falling behind.

Despite having the relatively low target of getting 15 per cent of all energy – including electricity, domestic heating and transport – from renewables by 2020, the UK still has more ground to make up than all other European Union countries except three.

The report, which is the latest update on progress, said the UK had reached 8.9 per cent in 2016 and admitted hitting the 2020 target would be challenging.

Leonie Greene of industry body Solar Trade Association said the figures underlined “how big a challenge it will be to meet the UK 2020 renewables target, which is modest by European standards”.

“It’s clear renewable energy now needs some serious ministerial attention,” she added.

The sector was not seeking further taxpayers’ money, Ms Greene stressed. “For solar we are not even asking for new subsidies – simply a fair and level playing field with other generation technologies.”

Alasdair Cameron, a renewable energy and climate campaigner at Friends of the Earth, said there was a danger that other countries think the UK was cosying up the US President, who has decided to withdraw from the Paris Agreement on climate change.

“The UK needs to make it perfectly clear it doesn’t stand with Donald Trump,” he said.

“One of the best ways to do that is to make sure we get ahead and meet the targets we have already committed to.

“If countries like the UK, one of the richest, most developed countries in the world, cannot do their fair share, it’s obviously a very negative signal to the rest of the world.”

Mr Cameron, who described the switch to a low-carbon economy as a new, global industrial revolution, said Britain was unlikely to meet the 15 per cent target unless the Government produced some “ambitious new policies”.

But he added: “I think if the UK gets serious about clean electricity, heating and transport, then it can certainly get pretty close.”

The UK target of 15 per cent was agreed as part of a wider EU commitment, that saw other countries given targets ranging from 10 per cent (Malta) to 49 per cent (Sweden).

Gareth Redmond-King, head of climate and energy policy at conservation group WWF, said the UK had done well in boosting the amount of renewable electricity generation.

However, the former civil servant added: “Where the UK is very much not on track is in relation to renewable heat in our homes, and renewable fuels in our transport; this is the reason we look likely to miss the 2020 target.”

Dr Doug Parr, chief scientist of Greenpeace UK, said: “Theresa May has been talking the talk on climate action, and now it’s time for her to walk the walk.

“The [Tory] manifesto reflected her intention to be a world leader on climate change, but first she needs to look closer to home, and ensure the UK’s transition to a low-carbon economy is not delayed.

“To hold her head up amongst other G20 heads of state, she’ll need to push forward the advantages that properly sustainable renewables like offshore wind have both for the planet and for UK jobs.”

For years, Britain has been widely regarded as a world leader in attempts to reduce climate change, but there have been ominous signs in recent years. There are also fears that the UK’s departure from the EU, which depending on the terms of the Brexit deal could mean the renewable target was no longer enforceable, will see a bonfire of environmental regulations.

The Government’s own independent advisers, the Committee on Climate Change, recently warned Ministers that global warming is “happening, not waiting” and their lack of action was “neither justifiable nor wise”.

One of Ms May’s first acts as Prime Minister was to scrap the dedicated Department for Energy and Climate Change, transferring its responsibility to the Department for Business, Energy and Industrial Strategy (BEIS).

The solar industry has complained the lack of a fair playing field with fossil fuels has brought it to the brink of collapse, and policies designed to discourage onshore wind farms have been introduced, despite these being the two cheapest forms of new electricity generation.

The Clean Growth Plan, the UK’s main climate change-fighting strategy, is only due to be published in September – about a year late.

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Ministers have also been forced twice by the courts to produce a better Clean Air Plan following legal action by campaigners ClientEarth, who are to sue for a third time.

Ms Merkel, the German Chancellor, has said the EU is “more determined than ever” to make the Paris Agreement on climate change a success, pledging she would not “overlook tensions” with the US over the issue when she meets Mr Trump at the G20.

In contrast, Ms May, who famously held hands with Mr Trump in Washington, was noticeably quiet over his decision to withdraw the US from the Paris Agreement, only belatedly expressing her disappointment in the mildest of terms.

In a statement, BEIS said the UK had surpassed interim targets for renewable energy in 2011/12, 2013/14 and 2015/16.

“We are currently progressing in line with the trajectory set out in the EU Renewable Energy Directive,” it said.

However, the Government’s report suggested the target might be difficult to achieve.

“The UK is now challenged to increase its share of renewable energy by a further 6.8 percentage points to meet its 2020 target of 15 per cent, the fourth highest increase required behind The Netherlands, France, and Ireland,” it said.

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And Antoinette Sandbach, a Conservative MP who was a member of the previous parliament’s Business, Energy and Industrial Strategy Committee, agreed more work was required.

“I do think it’s possible to hit the 15 per cent target, but it’s clearly going to require focus from the Government … and it looks like that focus is starting to happen in the transport sector,” she said, pointing to the Government’s plans to help boost the number of electric vehicles.

“It’s the transport sector that’s the greatest concern. I’m glad to see the Government has actually issued a report and they are focussing on it as clearly it is something that does need focussing on.”

While climate science denial has become common on the right of US politics, the same is not true in the UK – despite a few notable exceptions.

Ms Sandbach stressed global warming was “one of the greatest challenges our country … and our world faces”.