LONDON, Oct 21 (Bernama-PA Media/dpa) -- Urgent and stringent cuts in planet-heating emissions will be required to limit peak global warming to between 1.7 and 1.8 degrees Celsius above pre-industrial levels by mid-century, United Nations (UN) scientists have warned, reported PA Media/dpa.
The world is set to exceed the key threshold of 1.5 degrees of warming above pre-industrial levels, worsening the risks posed by climate change.
However, UN Secretary-General António Guterres said “overshoot is not surrender” as the UN Environment Programme (UNEP) outlined how the world could minimise the magnitude and duration of the overshoot and seek to bring temperatures back below 1.5 degrees as soon as possible.
The 1.5-degree threshold was a key element of the landmark 2015 UN Paris Agreement, under which countries pledged to keep global warming well below 2 degrees and pursue efforts to limit it to 1.5 degrees.
Scientists say failure to limit warming to 1.5 degrees will lead to increasingly frequent and intense extreme weather events, including heatwaves, droughts, wildfires and flooding, with far-reaching and severe impacts on human life, economies and nature.
It could also trigger multiple climate tipping points that could cause irreversible damage, including the breakdown of major ocean circulation systems, thawing permafrost and the collapse of tropical coral reef systems.
In its annual “Emissions Gap” report released on Wednesday, UNEP outlined various scenarios involving a temporary overshoot of the 1.5-degree threshold.
It found that the “lowest possible” scenario would now involve warming overshooting the threshold, peaking at between 1.7 and 1.8 degrees by mid-century, before returning to 1.5 degrees or below by 2100, with about a 50 per cent chance.
To get on 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.
However, UNEP experts found that countries’ current climate plans, known as nationally determined contributions (NDCs), which they are required to submit under the Paris Agreement, would reduce emissions by only 5 to 8 per cent by 2030 and 11 to 15 per cent by 2035, relative to 2025 levels.
Guterres said: “We can still keep it as small and as short as possible – and bring temperatures back below 1.5 degrees by the end of the century.”
Under current policies worldwide, UNEP projects that warming could reach 2.8 degrees Celsius this century and continue to rise thereafter.
If all NDCs are implemented and similar efforts continue, the agency projects that warming would be limited to 2.6 degrees.
These projections are higher than those in last year’s UNEP report, with experts attributing the increase to the United States’ withdrawal from the Paris Agreement and revised estimates of historical emissions.
New NDCs submitted by countries since last year’s report have made a negligible difference to these projections, it added.
Even under the most optimistic scenario, in which all NDCs and additional net-zero targets are achieved, global warming would be limited to only 2.1 degrees this century.
The UNEP report said advances in renewable energy and climate policies had delivered real emissions reductions across countries and sectors since the adoption of the Paris Agreement, with total energy supply from coal and oil growing more slowly than projected.
However, it warned that a massive global scale-up of efforts was needed to get on track to achieve the Paris Agreement’s goals, adding that there were more opportunities than ever to accelerate climate action.
UNEP Executive Director Inger Andersen said: “Every additional fraction of a degree and additional year of warming above 1.5 degrees 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 1.5 degrees 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.”
-- BERNAMA-PA MEDIA/dpa