Countries must slash emissions by five times their planned amount in the next 11 years if they are to avert disastrous global warming, the UN has warned.

Vanishing islands, widespread species extinctions and extreme weather have all been predicted under even the most optimistic climate predictions.

However, experts think the worst effects of climate change can be averted if the world breaks its dependence on carbon-emitting fossil fuels.

CO2 pollution increased in 2017 after a promising three-year decline, dashing hopes that the world had reached peak emissions. Initial reports suggest in 2018 this worrying trend will continue.

Despite efforts to eradicate fossil fuels in many countries, plans to slash emissions are still way off what is required to keep warming under 2C above pre-industrial levels.

This is even more pronounced if the more ambitious target of 1.5C recommended by many in the global climate science community is to be achieved.

In a new report, UN environment specialists predict that if this “emissions gap” is not closed by 2030, the world will never meet these targets, which are set out by the Paris climate agreement.

This echoes the scientific conclusions of the UN’s Intergovernmental Panel on Climate Change (IPCC) in October, which found emissions needed to halve in 12 years to avoid climate catastrophe.

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

The scientists behind that report predicted a world of melting Arctic sea ice, climate refugees and dying coral reefs as it soars past the 1.5C threshold.

“If the IPCC report represented a global fire alarm, this report is the arson investigation,” said UN environment deputy executive director Joyce Msuya.

“The science is clear: for all the ambitious climate action we’ve seen, governments need to move faster and with greater urgency. We’re feeding this fire while the means to extinguish it are within reach.”

Nations must set more ambitious commitments and triple their emissions cuts by 2030 to meet a 2C target, and increase cuts by five times to meet the 1.5C target.

If current trends continue, the Earth will likely heat up by 3.2C by the end of the century.

The report comes at a crucial time for climate change preparations, arriving shortly after the IPCC’s report and the week before important climate discussions begin at COP24 in Poland.

While governments have so far failed in stepping up to the challenge, climate experts said there was hope among the “doom and gloom” predictions.

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“It’s clear that governments can make global carbon emissions peak and decline soon if they simply do more of what’s proven to work, such as cutting energy waste and switching from coal to clean energy,” said Richard Black, director of the Energy and Climate Intelligence Unit

Dr Jian Liu, UN Environment’s chief scientist, said governments must act by subsidising renewable energy sources such as wind and solar, and taxing fossil fuels heavily instead of supporting them.

“If all fossil fuel subsidies were phased out, global carbon emissions could be reduced by up to 10 percent by 2030,” he said.

Despite global progress in renewable energy, much of the world still remains locked into high-polluting fuels like coal and oil, and opposition to climate science from major nations like the US and Brazil looks set to jeopardise the fight against global warming.

While the UK has cut emissions by more than 40 per cent since 1990, green groups say this progress is being hampered as the government stalls on switching to electric vehicles and supports fracking.

“This is the biggest threat humanity has faced and the urgency of action required is shocking. What are governments waiting for?” said Greenpeace International executive director Jennifer Morgan.

With cities around the world banning non-electric cars, regional governments phasing out coal power and banks turning their back on fossil fuel investments, Ms Morgan said hope may now lie with these non-state actors.

Extreme heatwaves this summer were widely viewed as a glimpse of future life in a warmer world, and an approaching El Niño event could see 2019 take the crown for hottest year on record.