The world has three years to start making significant reductions in greenhouse gas emissions or face the prospect of dangerous global warming, experts have warned in an article in the prestigious journal Nature.

Calling for world leaders to be guided by the scientific evidence rather than “hide their heads in the sand”, they said “entire ecosystems” were already beginning to collapse, summer sea ice was disappearing in the Arctic and coral reefs were dying from the heat.

The world could emit enough carbon to bust the Paris Agreement target of between 1.5 to 2 degrees Celsius in anything from four to 26 years if current levels continue, the article said.

Global emissions had been rising rapidly but have plateaued in recent years. The experts, led by Christiana Figueres, who as Executive Secretary of the United Nations Framework Convention on Climate Change played a key role in the Paris Agreement, said they must start to fall rapidly from 2020 at the latest.

“The year 2020 is crucially important for another reason, one that has more to do with physics than politics,” they said.

Citing a report published in April, they added: “Should emissions continue to rise beyond 2020, or even remain level, the temperature goals set in Paris become almost unattainable.

“Lowering emissions globally is a monumental task, but research tells us that it is necessary, desirable and achievable.”

The article was signed by more than 60 scientists, such as Professor Michael Mann of Pennsylvania State University, politicians, including former Mexican President Felipe Calderon and ex-Irish President Mary Robinson, businesspeople like Paul Polman, chief executive of Unilever, investment managers, environmental campaigners and others.

Since the 1880s, the world’s temperature has risen by about 1C because of greenhouse gases resulting from human activity – a process predicted by a Swedish Nobel Prize-winning scientist in 1895.

The Nature article laid out the effect of this sudden increase on the planet.

10 photographs to show to anyone who doesn't believe in climate change Show all 10 1 /10 10 photographs to show to anyone who doesn't believe in climate change 10 photographs to show to anyone who doesn't believe in climate change A group of emperor penguins face a crack in the sea ice, near McMurdo Station, Antarctica Kira Morris 10 photographs to show to anyone who doesn't believe in climate change Floods destroyed eight bridges and ruined crops such as wheat, maize and peas in the Karimabad valley in northern Pakistan, a mountainous region with many glaciers. In many parts of the world, glaciers have been in retreat, creating dangerously large lakes that can cause devastating flooding when the banks break. Climate change can also increase rainfall in some areas, while bringing drought to others. Hira Ali 10 photographs to show to anyone who doesn't believe in climate change Smoke – filled with the carbon that is driving climate change – drifts across a field in Colombia. Sandra Rondon 10 photographs to show to anyone who doesn't believe in climate change Amid a flood in Islampur, Jamalpur, Bangladesh, a woman on a raft searches for somewhere dry to take shelter. Bangladesh is one of the most vulnerable places in the world to sea level rise, which is expected to make tens of millions of people homeless by 2050. Probal Rashid 10 photographs to show to anyone who doesn't believe in climate change Sindh province in Pakistan has experienced a grim mix of two consequences of climate change. “Because of climate change either we have floods or not enough water to irrigate our crop and feed our animals,” says the photographer. “Picture clearly indicates that the extreme drought makes wide cracks in clay. Crops are very difficult to grow.” Rizwan Dharejo 10 photographs to show to anyone who doesn't believe in climate change Hanna Petursdottir examines a cave inside the Svinafellsjokull glacier in Iceland, which she said had been growing rapidly. Since 2000, the size of glaciers on Iceland has reduced by 12 per cent. Tom Schifanella 10 photographs to show to anyone who doesn't believe in climate change A river once flowed along the depression in the dry earth of this part of Bangladesh, but it has disappeared amid rising temperatures. Abrar Hossain 10 photographs to show to anyone who doesn't believe in climate change A shepherd moves his herd as he looks for green pasture near the village of Sirohi in Rajasthan, northern India. The region has been badly affected by heatwaves and drought, making local people nervous about further predicted increases in temperature. Riddhima Singh Bhati 10 photographs to show to anyone who doesn't believe in climate change A factory in China is shrouded by a haze of air pollution. The World Health Organisation has warned such pollution, much of which is from the fossil fuels that cause climate change, is a “public health emergency”. Leung Ka Wa 10 photographs to show to anyone who doesn't believe in climate change Water levels in reservoirs, like this one in Gers, France, have been getting perilously low in areas across the world affected by drought, forcing authorities to introduce water restrictions. Mahtuf Ikhsan

“Ice sheets in Greenland and Antarctica are already losing mass at an increasing rate,” it said.

“Summer sea ice is disappearing in the Arctic and coral reefs are dying from heat stress – entire ecosystems are starting to collapse.”

And it added: “The social impacts of climate change from intensified heatwaves, droughts and sea-level rise are inexorable and affect the poorest and weakest first.”

Humanity is currently emitting about 41 gigatonnes of carbon dioxide a year, but if the Paris target is to be met it only has a carbon ‘budget’ of between 150 and 1,050 gigatonnes.

“If the current rate of annual emissions stays at this level, we would have to drop them almost immediately to zero once we exhaust the budget. Such a ‘jump to distress’ is in no one’s interest. A more gradual descent would allow the global economy time to adapt smoothly,” the experts wrote.

But they urged people not to abandon hope.

“The good news is that it is still possible to meet the Paris temperature goals if emissions begin to fall by 2020,” they said.

Donald Trump, the US President and climate science-denier, has pledged to withdraw the US from the Paris Agreement, which will take until 2020.

The Nature article urged world leaders to take the opposite approach by using science to guide policy and defending scientists.

“Those in power must stand up for science,” it said.

“French President Emmanuel Macron’s Make Our Planet Great Again campaign [a deliberate play on Mr Trump’s Make America Great Again slogan] is a compelling example.

“He has spoken out to a global audience in support of climate scientists, and invited researchers to move to France to help accelerate action and deliver on the Paris agreement.”

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Any delay would pose a threat to human prosperity.

“With no time to wait, all countries should adopt plans for achieving 100 per cent renewable electricity production, while ensuring that markets can be designed to enable renewable-energy expansion,” the experts wrote.

Optimism was also important.

“Recent political events have thrown the future of our world into sharp focus,” they said. “But as before Paris, we must remember that impossible is not a fact, it’s an attitude. It is crucial that success stories are shared.

“There will always be those who hide their heads in the sand and ignore the global risks of climate change.