‘Unprecedented changes’ needed to stop global warming as UN report reveals islands starting to vanish and coral reefs dying

Greenhouse gas emissions must be cut almost in half by 2030 to avert global environmental catastrophe, including the total loss of every coral reef, the disappearance of Arctic ice and the destruction of island communities, a landmark UN report has concluded.

Drawing on more than 6,000 scientific studies and compiled over two years, the Intergovernmental Panel on Climate Change (IPCC) findings, released this morning, warn enormous and rapid changes to the way everyone on Earth eats, travels and produces energy need to be brought in immediately.

Though the scientists behind the report said there is cause for optimism, they recognised the grim reality that nations are currently nowhere near on track to avert disaster.

The worst effects of global warming will only be prevented if the global temperature increase stays below 1.5C, a figure the scientists think will be exceeded within around 20 years.

Under current climate commitments by world leaders, the Earth will be 3C warmer by the end of the century.

“Limiting warming to 1.5C is possible within the laws of chemistry and physics, but doing so would require unprecedented changes,” said Professor Jim Skea of Imperial College London, who contributed to the report.

Another contributor, Professor Myles Allen from the University of Oxford, added: “If emissions rise above the current level then warming will accelerate, so we might even get to 1.5C earlier than this.”

Crucially, if the world is to avoid crossing the 1.5C threshold, CO2 emissions must be cut drastically to 45 per cent on 2010 levels by 2030, and to achieve “net zero” levels by 2050.

This means not only a massive switch away from fossil fuels to renewable energy sources, but also investing in technologies that actually suck any remaining CO2 out of the air.

The world has already passed 1C of warming since 19th-century industrialisation began spewing greenhouse gases into the atmosphere, and many regions are already suffering the effects as heatwaves, droughts and floods become more intense and frequent.

Devised by the IPCC, the aim of the new report was to establish what the world can expect in two distinct global warming futures: 1.5C and 2C.

Climate scientists used to think that 2C was a suitable level at which to cap global warming, but when the Paris climate agreement was settled in 2015 it reflected a changing consensus.

Its first goal was to keep global temperature rise “well below” 2C, but added that nations would “pursue efforts to limit the temperature increase even further to 1.5C”.

Many countries, particularly those consisting of low-lying islands such as the Marshall Islands, saw any warming beyond this lower bound as an effective death sentence – predicting their homes would be engulfed by rising sea levels.

After the summit the UN asked the IPCC to establish what the real-world difference between these two targets would be, and what would be needed to achieve them.

Following a week of scientists and government delegates hashing out its final wording in the South Korean city of Incheon, the conclusions of the Special Report on Global Warming of 1.5C were revealed to the world on Monday.

Though the harm caused by 1.5C warming is not trivial, the results showed stark differences between the two targets.

Unlike 2C, the lower target will see corals decline by about 80 per cent, an ice-free Arctic summer every century and 10cm less sea level rise. This seemingly small difference in sea level rise will have a massive impact for coastal regions and islands, preventing 10 million people from losing their homes to the waves.

Crucially, if the world is to avoid crossing the 1.5C threshold, carbon emissions must be cut drastically to achieve “net zero” levels by 2050. This means not only a massive switch away from fossil fuels to renewable energy sources, but also investing in technologies that suck any remaining CO2 out of the air.

Carbon capture techniques may allow the world to “overshoot” the 1.5C mark before bringing it back below the threshold, but this could be a risky strategy.

While some of these measures are straightforward and proven to work – namely “nature-based” methods like planting trees – others are untested technologies that some experts fear will not meet expectations.

Whatever leaders decide to do, the scientists warned that changes will need to happen fast, and they will certainly impact people’s lives.

Shifts towards less resource-intensive diets such as those that include less meat, and the rollout of electric cars to replace high-polluting petrol and diesel models are among the changes that will help with this transition in the coming decades.

“There is not one thing you can do like going vegan that will solve everything; it will have to be a little bit of everything,” said Dr Heleen de Coninck of Radboud University.

“There is, however, no reason to assume we cannot lead a comfortable and fulfilling life in a 1.5C world.”

Dr Debra Roberts, who also contributed to the report, said in creating it they had given those in power the tools to make these important decisions. Their results will be put to the test at the next major climate change meeting this December in Poland.

“The next few years are probably the most important in our history,” said Dr Roberts.

As key nations like the US and Australia appear to turn their backs on global climate agreements, the scientists also noted that efforts to stop warming would go hand in hand with eradicating global poverty and making the world a fairer place.

The report was welcomed by experts across the scientific, business and NGO communities, who noted that the urgency of the IPCC scientists must now be mirrored by politicians.

“We have the targets, we have the solutions and the difference between impossible and possible is political leadership,” said Dr Stephen Cornelius, chief advisor on climate change at WWF

Professor Mark Maslin, a climatologist at University College London, said the report was nothing short of “revolutionary”.

“At the end of this century historians will look back and realise that the IPCC 1.5C Special Report was the moment when a new vision for the 21st century emerged, leading to a safer, sustainable and more equitable world,” he said.