Protesters have scaled the German embassy in London to urge Germany to stop mining coal, as a major UN report calls for unprecedented action to tackle climate change.

Many western European nations, including the UK, have committed to rapidly phasing out the high-polluting fossil fuel in their power stations over the next few years.

But Germany, which is home to Europe’s biggest open-cast coal mine, has made no such pledge, and current mining commitments extend to 2040.

Five Greenpeace climbers scaled the embassy building early on Monday morning, shortly before scientists at a press conference in South Korea made their call for the world to slash its CO2 emissions.

They unfurled a banner covering one side of the building reading: “EXIT COAL”.

“Today we received an unequivocal warning from the world’s greatest experts on the biggest threat we face. We need to kick our fossil fuel addiction, and fast,” said Franziska Grobke, one of the climbers.

“In that context, it’s genuinely difficult to believe that Europe’s technological superpower Germany is still relying on dirty, Victorian, coal-fired steam engines to power itself.”

In light of the new report produced by the Intergovernmental Panel on Climate Change (IPCC), Ms Grobke said it was clear all governments needed to speed up their emissions reductions.

IPCC: limiting global warming would require 'unprecedented changes', says Professor Jim Skea

The scientists concluded that to avoid the worst effects of climate change, warming must be limited to 1.5C. With the commitments currently in place by world governments, this target will be broken within decades.

“We are here to urge Angela Merkel to stop letting coal lobbyists make Germany’s climate policy,” said Ms Grobke.

“She needs to listen to the world’s climate scientists and catch up with other wealthy European nations.”

Greenpeace is calling on Germany to adopt a 2030 coal exit plan. The UK is currently aiming to eradicate use of coal by 2025 and France by 2022.

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Thousands of anti-coal demonstrators marched on Germany’s Hambach forest on Saturday after a court victory saved part of the ancient woodland from being felled to make way for mining.

The massive event was seen as a celebration of this small success, but the organisers emphasised there remains a long way to go.

“This rally is about demanding that the German government break the deadlock of a climate policy that has failed to reduce carbon emissions for nearly a decade now, but it also is about showing governments everywhere that a growing climate movement is demanding an end to dirty and outdated fossil fuels,” said Martin Kaiser, executive director of Greenpeace Germany.

The Hambach forest mine has already resulted in 90 per cent of trees in the region being cleared.

Following the IPCC scientists’ conclusions, it is now up to the world’s governments to devise stricter emissions targets that will involve cutting CO2 emissions by nearly half within 12 years.