Current government plans to cut greenhouse gases are not nearly enough to prevent catastrophic climate change, putting Earth on course for between 2.1°C and 2.9°C warming by the end of the century, a UN report published on Wednesday found.
Despite some progress in the past year, governments need to take urgent action by 2030 to ensure that temperature increases are kept below 2°C and ideally 1.5°C as laid out in the 2015 Paris Agreement.
United Nations Framework Convention on Climate Change analysed plans submitted by governments around the world on how they will try to cut emissions and compared that to the scientific models.
These plans show that emissions will rise 10.6 per cent on 2010 levels by 2030.
However, UN climate experts say that to meet the target of no more than 1.5°C of temperature rise compared to pre-industrial levels, the world needs to slash emissions by 45 per cent.
"We are still nowhere near the scale and pace of emission reductions required to put us on track toward a 1.5°C world," said Simon Stiell, executive secretary of UN Climate Change.
"To keep this goal alive, national governments need to strengthen their climate action plans now and implement them in the next eight years."
The planet is already being battered by climate-enhanced heatwaves, storms and floods after 1.2°C of warming.
Scientists have warned that any rise above 1.5°C risks the collapse of ecosystems and the triggering of irreversible shifts in the climate system.
However, the report found that if all governments met their pledges on emission cuts, then total output would be 52.4 billion tonnes of carbon-dioxide equivalent in 2030, down 0.3 per cent from 2019 levels.
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This indicated that Co2 emissions could peak at the end of this decade and start to reduce before 2050 – a rosier picture than last year’s report, which suggested that emissions would continue to grow beyond 2030.
However, even if all the promises were fulfilled, there would still be an excess of 16 billion tonnes of Co2 above the threshold required to keep global warming at 2°C.
The wide range in the warming estimates on what this means — an increase between 2.1°C and 2.9°C — is due to uncertainty over whether countries can implement their plans.
If emissions are not reduced sufficiently by 2030, cuts will need to be much sharper after that date to compensate for the slow start on the path to net zero, the requisite for halting global warming, the UNFCCC report said.
“We’re bending the curve on emissions downwards, they are projected to go in the right direction,” Mr Stiell said. “But they are not going down enough fast enough, far enough.”
A second report by the UN found that emissions could be about 68 per cent lower in 2050 than they were in 2019 if all the countries’ commitments were implemented. However, it warned that action must not be delayed as some countries were aiming for a slower start and deeper cuts towards the middle of the century.
“Nations must strengthen their plans now and implement them in the next eight years,” Mr Stiell said.
When nations met in Glasgow last year for a previous round of climate negotiations, they agreed to speed up their climate pledges to cut carbon pollution and increase financial flows to vulnerable developing nations.
But only 24 countries out of 193 had updated their plans at the time of the report, which Mr Stiell said was "disappointing".
"Government decisions and actions must reflect the level of urgency, the gravity of the threats we are facing and the shortness of the time we have remaining to avoid the devastating consequences of runaway climate change," he said.
From 2020 to 2021, the increase in levels of Co2, the main greenhouse gas emitted through human activities and the primary driver of climate change, was larger than the average annual growth rate over the past decade.
Levels continue to rise this year. Methane concentrations in 2021 saw the biggest year-on-year jump since measurements began four decades ago.
“The continuing rise in concentrations of the main heat-trapping gases, including the record acceleration in methane levels, shows that we are heading in the wrong direction,” said Petteri Taalas, secretary general of the World Meteorological Organisation.
“There are cost-effective strategies available to tackle methane emissions, especially from the fossil fuel sector, and we should implement these without delay.”
While methane has 28 times greater warming potential than CO2, it dissolves in the atmosphere in less than a decade, meaning its effect on climate is reversible if methane emissions are slashed fast, Mr Taalas said.
In contrast, Co2 remains in the atmosphere for centuries, so gases emitted today will continue warming the planet in the future, even if humanity manages to eliminate net emissions within the coming decades.