By Matt McGrath
Environment correspondent Published 9 August
Human activity is changing the climate in unprecedented and sometimes irreversible ways, a major UN scientific report has said.
The landmark study warns of increasingly extreme heatwaves, droughts and flooding, and a key temperature limit being broken in just over a decade.
The report “is a code red for humanity”, says the UN chief.
But scientists say a catastrophe can be avoided if the world acts fast.
There is hope that deep cuts in emissions of greenhouse gases could stabilise rising temperatures.
Echoing the scientists’ findings, UN Secretary General António Guterres said: “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.”
The sober assessment of our planet’s future has been delivered by the UN’s Intergovernmental Panel on Climate Change (IPCC), a group of scientists whose findings are endorsed by the world’s governments.
Their report 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.
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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.”
Petteri Taalas, Secretary-General of the World Meteorological Organization, said: “By using sports terms, one could say the atmosphere has been exposed to doping, which means we have begun observing extremes more often than before.”
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 key points
- 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.”
Five future impacts
- Temperatures will reach 1.5C above 1850-1900 levels by 2040 under all emissions scenarios
- The Arctic is likely to be practically ice-free in September at least once before 2050 in all scenarios assessed
- There will be an increasing occurrence of some extreme events “unprecedented in the historical record” even at warming of 1.5C
- Extreme sea level events that occurred once a century in the recent past are projected to occur at least annually at more than half of tidal gauge locations by 2100
- There will be likely increases in fire weather in many regions