UN scientists have found that, under current climate policies across the world, global warming could reach 2.8C this century and continue to rise thereafter.
The warning came in the United Nations Environment Programme’s (UNEP) annual “Emissions Gap” report, released on Wednesday.
The world is set to pass the key threshold of 1.5C warming above pre-industrial levels, worsening the risks of climate change.
In the Wednesday report, the UNEP outlined different 1.5C overshoot scenarios, which included a projection suggesting global warming could break 2.8C before 2100.
Nations’ current climate plans, called nationally determined contributions (NDCs), would only reduce emissions by 5-8 per cent by 2030 and 11- 15 per cent by 2035, relative to 2025 levels, the report detailed.
Those NDCs are published as part of the Paris Agreement from which the US withdrew for a second time earlier this year.
If all NDCs were delivered and efforts to further reduce global emissions continued, the agency reported warming would be limited to 2.6C.
These projections were higher than the UNEP report’s projections from the previous year, with the experts attributing this to the US withdrawal from the Paris Agreement alongside revised estimates of historical emissions.
New NDCs submitted by countries since last year’s report have made a negligible difference for these projections, it added.
Even in the most optimistic scenario, where all NDCs plus additional net-zero targets are achieved, global warming would only be limited to 2.1C in this century.
Deep and rapid reductions in greenhouse gas emissions are vital if peak global warming is to be kept to 1.7C-1.8C above pre-industrial levels by mid-century, the UN scientists said.
‘Overshoot is not surrender’
UN Secretary-General Antonio Guterres said “overshoot is not surrender”, as the UNEP detailed how nations might limit the scale and duration of the breach, seeking to bring warming back under 1.5C as quickly as possible.
The benchmark formed a core element of the landmark 2015 UN Paris Agreement, which committed nations to capping temperature rises well below 2C while striving for 1.5C.
Scientists warn that failing to contain warming will drive more frequent and severe extreme weather, from heatwaves and droughts to wildfires and flooding, with grave consequences for humanity, nature and global economies.
It could also trigger severe environmental tipping points, causing lasting destruction through permafrost thaw, coral reef collapses and ocean circulation failures.
The UN report found the “lowest possible” scenario would now see an overshoot of 1.7C to 1.8C by the middle of the century, and global temperature rise returning to or below 1.5C by 2100, with about a 50 per cent chance.
To get on to this pathway, global emissions would have to be reduced by 18 per cent by 2030, 45 per cent by 2035 and 69 per cent by 2040, all relative to 2025 levels, it said.
“Overshoot is not surrender,” Mr Guterres said.
“We can still keep it as small and as short as possible – and bring temperatures back below 1.5C by the end of the century.”
The UNEP report said advances in renewable energy and climate policies have delivered real emission reductions across countries and sectors since the adoption of the Paris Agreement, with total energy supply from coal and oil growing slower than projected.
However, it also warned of the massive global scale-up required to get on track to achieve the goals of the Paris Agreement and that there are more opportunities than ever to accelerate action.
Executive director of UNEP Inger Andersen said: “Every additional fraction of a degree and additional year of warming above 1.5C increases climate impacts and risks, such as the deadly floods, heatwaves and wildfires that have plagued many nations this year.
“We must pull out all the stops to minimise peak warming and return to 1.5C by the end of the century. This is possible.
“We have a wealth of success stories showing that emissions can be cut quickly.
“It is now up to nations to urgently put in place policies that spark fast, deep and sustained emissions reductions, and put the world on track for a more stable climate and more stable economies and societies.”
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