The biggest UN climate report since 2013 is set to highlight the threats faced by our planet, with one UN official describing the pandemic as a "warning from the planet".
Joyce Msuya, assistant secretary general of the United Nations and deputy executive director of the UN Environment Programme (UNEP), said: "While the climate crisis, together with biodiversity loss and pollution, has indeed been under way for decades, the COVID-19 pandemic has brought this triple planetary crisis into sharp focus.
"The pandemic is a warning from the planet that much worse lies in store unless we change our ways."
Over the next two weeks, top scientists with the Intergovernmental Panel on Climate Change (IPCC) will finalise the first instalment of its sixth Assessment Report.
The report will expand on the last such IPCC report in 2013 by focusing more on extreme weather and regional impacts.
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The last IPCC report warned of the dangers of allowing unchecked climate change, and was a major influence on the Paris 2015 climate talks.
"As I speak, it is clear that extreme weather is the new normal. From Germany to China to Canada or the United States: wildfires, floods, extreme heat waves. It is an ever growing tragic list," Msuya said.
"2021 must mark the beginning of the era of action, and it must be the year where science reigns supreme.”
In recent weeks and months, Europe and central China have seen torrential rain followed by deadly flooding.
This summer has seen a nightmarish heat wave roasting the US, which saw Death Valley in California record what could be the highest reliably recorded temperature in history.
Temperatures of 49C have been recorded in Canada and tropical heat in Finland and Ireland.
Climate scientist Michael Mann, of Pennsylvania State University, said: "It's not so much that climate change itself is proceeding faster than expected — the warming is right in line with model predictions from decades ago.
"Rather, it's the fact that some of the impacts are greater than scientists predicted."
That suggests that climate modeling may have been underestimating the "the potential for the dramatic rise in persistent weather extremes," Mann said.
Meanwhile Corinne Le Quere, a climate scientist at the University of East Anglia, said: "Global warming was well projected, but now you see it with your own eyes."
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