Climate change: UN report 'code red for humanity'

Humanity's damaging impact on the climate is a 'statement of fact', say UN scientists in a landmark study.

The report says that ongoing emissions of warming gases could also see a key temperature limit broken in just over a decade, reports BBC.

The authors also show that a rise in sea levels approaching 2m by the end of this century "cannot be ruled out".

But there is new hope that deep cuts in emissions of greenhouse gases could stabilise rising temperatures.

This sober assessment from the Intergovernmental Panel on Climate Change (IPCC) features in a 42-page document known as the Summary for Policymakers.

It leads a series of reports that will be published over the coming months and is the first major review of the science of climate change since 2013. Its release comes less than three months before a key climate summit in Glasgow known as COP26.

"Today's IPCC Working Group 1 Report is a code red for humanity," said UN Secretary-General, António Guterres.

"If we combine forces now, we can avert climate catastrophe. But, as today's report makes clear, there is no time for delay and no room for excuses. I count on government leaders and all stakeholders to ensure COP26 is a success."

In strong, confident tones, the IPCC's document says "it is unequivocal that human influence has warmed the atmosphere, oceans and land".

According to Prof Ed Hawkins, from the University of Reading, UK, and one of the report's authors, the scientists cannot be any clearer on this point.

"It is a statement of fact, we cannot be any more certain; it is unequivocal and indisputable that humans are warming the planet."

The authors say that since 1970, global surface temperatures have risen faster than in any other 50-year period over the past 2,000 years.

This warming is "already affecting many weather and climate extremes in every region across the globe".

Whether it's heatwaves like the ones recently experienced in Greece and western North America, or floods like those in Germany and China, "their attribution to human influence has strengthened" over the past decade.

IPCC report fast facts

• Global surface temperature was 1.09C higher in the decade between 2011-2020 than between 1850-1900.
• The past five years have been the hottest on record since 1850
• The recent rate of sea level rise has nearly tripled compared with 1901-1971
• Human influence is "very likely" (90%) the main driver of the global retreat of glaciers since the 1990s and the decrease in Arctic sea-ice
• It is "virtually certain" that hot extremes including heatwaves have become more frequent and more intense since the 1950s, while cold events have become less frequent and less severe

The new report also makes clear that the warming we've experienced to date has made changes to many of our planetary support systems that are irreversible on timescales of centuries to millennia.

The oceans will continue to warm and become more acidic. Mountain and polar glaciers will continue melting for decades or centuries.

"The consequences will continue to get worse for every bit of warming," said Prof Hawkins.

"And for many of these consequences, there's no going back."

When it comes to sea-level rise, scientists have modelled a likely range for different levels of emissions.

However, a rise of around 2m by the end of this century cannot be ruled out - and neither can a 5m rise by 2150.

Such outcomes, while unlikely, would threaten many millions more people in coastal areas with flooding by 2100.

One key aspect of the report is the expected rate of temperature rise and what it means for the safety of humanity.

Almost every nation on Earth signed up to the goals of the Paris climate agreement in 2015.

This pact aims to keep the rise in global temperatures well below 2C this century and to pursue efforts to keep it under 1.5C.

This new report says that under all the emissions scenarios considered by the scientists, both targets will be broken this century unless huge cuts in carbon take place.

The authors believe that 1.5C will be reached by 2040 in all scenarios. If emissions aren't slashed in the next few years, this will happen even earlier.

This was predicted in the IPCC's special report on 1.5C in 2018 and this new study now confirms it.

"We will hit one-and-a-half degrees in individual years much earlier. We already hit it in two months during the El Niño in 2016," said Prof Malte Meinshausen, an IPCC author from the University of Melbourne in Australia.