Global carbon emissions must fall by more than 7% a year for the next decade to meet targets set out by the Paris Agreement on climate change, the UN has warned.
In an annual report published Tuesday, the UN Environment Programme (UNEP) said its outlook for climate change was "bleak," adding that countries had "collectively failed to stop the growth in global greenhouse emissions, meaning that deeper and faster cuts are now required."
According to UNEP's analysts, 2020 would be a "critical year for climate action," with global temperatures currently on track to be 3.2 degrees Celsius warmer by the end of the century even if current commitments were met by each country.
Under the Paris Agreement — a landmark deal adopted in 2015 and signed by 195 countries — nations agreed to a framework to prevent global temperatures from rising by any more than 2 degrees Celsius, although the treaty aims to prevent global temperature rises exceeding 1.5 degrees Celsius.
In order to limit temperature rises to 2 degrees Celsius, UNEP said global emissions now need to fall by 2.7% per year for the next 10 years, while an annual emissions cut of 7.6% will be required to meet the 1.5 degrees Celsius target.
If serious climate action had begun in 2010, the cuts required to meet those objectives would have been between 0.7% and 3.3% a year, according to the report.
"Evidently, greater cuts will be required the longer that action is delayed," its authors warned.
The report showed that China, which has seen emissions surge in recent decades, was by far the world's biggest source of greenhouse gases last year, followed by the U.S. and the EU. However, when emissions were measured per capita, the U.S. led the way, followed by Russia and Japan.
Its authors called on G-20 members — which account for 78% of all emissions — to lead the way, claiming enhanced action from those economies would be "essential for the global mitigation effort."
UNEP also laid out specific actions that G-20 members could take.
China, for example, should ban all new coal-fired plants, continue governmental support for renewables and support the uptake of electric vehicles.
Meanwhile, UNEP called on the EU to adopt regulation to refrain from investment in fossil fuels and urged India to take actions including an expansion of mass public transit systems.
Developing economies are still permitted to increase their emissions under the Paris Agreement.
In the report, the UN also suggested steps that could be taken by the U.S. to reduce its emissions. They included introducing carbon pricing and regulations on power plants to achieve a carbon-free electricity supply, as well as strengthening the fuel and vehicle economies to be in line with zero emissions for new cars by 2030.
U.S. President Donald Trump announced he would withdraw the United States from the Paris Agreement in 2017, claiming that staying in would cost 2.7 million American jobs by 2025. Earlier this month, the Trump administration began the process to formally exit the treaty.
"Countries simply cannot wait until the end of 2020, when new climate commitments are due, to step up action," Inger Andersen, UNEP's executive director, said in a press release Tuesday. "They — and every city, region, business and individual — need to act now."
UNEP's report came after the World Meteorological Organization (WMO) said Monday that greenhouse gases in the atmosphere had hit a record high.
Meanwhile, a study published Monday showed that 2019 was set to see the largest ever fall in power produced from coal.