Countries are "significantly off-schedule" to meet the goals of the Paris climate agreement, a UN-backed report has warned.
In 2015, almost all of the world's countries pledged to limit global warming to "well below" 2C above pre-industrial levels and to strive to keep temperatures at 1.5C by the end of the century.
By the COP26 climate talks this November in Glasgow, countries are due to finalise their national action plans (nationally determined contributions, or NDCs) to cut greenhouse gas emissions under the Paris Agreement.
Carbon emissions are rapidly recovering after a temporary blip due to economic slowdown caused by COVID-19 and are "nowhere close" to reduction targets, according to the United in Science 2021 report.
CO2 emissions peaked in 2019, followed by a drop of 5.6% in 2020 due to the COVID-19 pandemic, the study said.
The average global temperature for the past five years was among the warmest on record, estimated at 1.06C to 1.26C above pre-industrial levels.
There is a 40% chance that temperatures will breach the threshold of 1.5C in the next five years, the analysis found.
Even if emissions are reduced, sea levels will continue to rise and threaten low-lying islands and coastal populations throughout the world, according to the report.
The authors said human-induced climate change is already increasing the frequency and intensity of many weather and climate extremes in every region across the globe and warned of increased heat-related deaths linked to rising temperatures.
"We are still significantly off-schedule to meet the goals of the Paris Agreement," said UN Secretary-General Antonio Guterres, warning that "time is running out".
He said this year has seen fossil fuel emissions bounce back, greenhouse gas concentrations continue to rise and severe human-enhanced weather events that have affected health, lives and livelihoods on every continent.
"Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5C will be impossible, with catastrophic consequences for people and the planet on which we depend," he said.
He said that for COP26 to be a "turning point" all countries need to commit to net zero emissions by 2050, backed up by concrete long-term strategies, and enhanced nationally determined contributions which collectively cut global emissions by 45% by 2030, compared with 2010 levels.
"We need a breakthrough on protecting people and their livelihoods, with at least half of all public climate finance committed to building resilience and helping people adapt," he said.
He also called for more financial support for developing countries so they can take climate action.
"There is no alternative if we are to achieve a safer, more sustainable and prosperous future for all," he added.
Professor Petteri Taalas, the Secretary-General of the World Meterological Organisation, said: "Throughout the pandemic we have heard that we must build back better to set humanity on a more sustainable path and to avoid the worst impacts of climate change on society and economies.
"This report shows that so far in 2021 we are not going in the right direction."
The United in Science 2021 report was coordinated by the World Meteorological Organisation, with input from the UN Environment Programme, the World Health Organisation, the Intergovernmental Panel on Climate Change, the Global Carbon Project, the World Climate Research Programme and the Met Office.
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