The United Nations weather monitoring body has announced that key climate change indicators set record highs in 2021, warning that the Earth's energy system is driving humanity towards catastrophe.
In its "State of the Global Climate in 2021" report, the UN's World Meteorological Organisation (WMO) says that greenhouse gas concentrations, sea level rise, ocean heat and ocean acidification all set new records last year.
According to UN Secretary General Antonio Guterres, the annual overview is "a dismal litany of humanity's failure to tackle climate disruption".
He added: "The global energy system is broken and bringing us ever closer to climate catastrophe."
The UN chief underlined that the world must end fossil fuel pollution and accelerate renewable energy transition before we "incinerate our only home."
The WMO said human activity was causing planetary-scale changes on land, in the ocean and in the atmosphere, with harmful and long-lasting ramifications for ecosystems.
The report released in Geneva this Wednesday confirmed that the past seven years have been the top seven hottest years on record.
Back-to-back La Niña events at the start and end of 2021 had a cooling effect on global temperatures last year.
Nevertheless, it was still one of the warmest years ever recorded, with the average global temperature in 2021 about 1.11°Celsius above pre-industrial levels.
The 2015 COP21 Paris Agreement on climate change saw countries agree to cap global warming at "well below" 2°C above average levels measured between 1850 and 1900 - and 1.5°C if possible.
WMO chief Petteri Taalas remarked: "Our climate is changing before our eyes.
"The heat trapped by human-induced greenhouse gases will warm the planet for many generations to come," he says .
The conclusion is that sea levels will keep on rising, ocean heat and acidification will continue for hundreds of years unless "the means to remove carbon from the atmosphere are invented."
Signs in the seas
As ocean heat hit a record high last year, exceeding the 2020 value, it is expected that the upper 2,000 metres of the ocean will continue to warm in the future.
The WMO report adds that the temperature rise was penetrating to ever deeper levels of the oceans, creating "a change which is irreversible on centennial to millennial timescales."
The ocean absorbs around 23 percent of the annual emissions of human-caused CO² into the atmosphere.
While this slows the rise of atmospheric CO² concentrations, CO² reacts with seawater and leads to ocean acidification.
The UN's Intergovernmental Panel on Climate Change has concluded with "very high confidence" that open ocean surface acidity is at its highest level "for at least 26,000 years".
Meanwhile, Guterres has proposed a five-point action plan to jump-start the transition to renewable energy "before it's too late".
Among them, he suggests ending fossil fuel subsidies, tripling investment in renewable energy and making renewable energy technology - such as battery storage - freely available.
"If we act together," says the UN chief, "renewable energy transformation can be the peace project of the 21st century."