Climate change has been altering the Earth in “unprecedented” ways for thousands – and in some cases, hundreds of thousands – of years, according to a dazzling report released by the United Nations on Monday.
The sobering assessment also found that some of the changes that are already happening, such as warming oceans and rising sea levels, are “irreversible for centuries, if not millennia.”
The report is the most comprehensive assessment of the UN Intergovernmental Panel on Climate Change (IPCC) since 2013 and provides the strongest case to date for man-made global warming, claiming that it is “unequivocal that human influence has warmed the atmosphere, oceans and land”.
The report also found that climate change is intensifying, occurring at an accelerating rate and already affecting all regions of the planet.
“It has been clear for decades that the Earth’s climate is changing, and the role of human influence on the climate system is undisputed,” said Valérie Masson-Delmotte, co-chair of IPCC Working Group I , in a press release.
The IPCC, established in the late 1980s, is made up of thousands of scientists from 195 member governments who look at the most recent published and peer-reviewed research on global warming and compile the results in a report on global warming. current state of the climate. The assessment, which includes an overview of the future risks and impacts of climate change, generally represents a consensus within the scientific community. Over 230 authors contributed to the latest report.
The assessment comes less than three months before world leaders meet from October 31 to November 12 in Glasgow, Scotland, for the 2021 United Nations Climate Change Conference. Countries are expected to set ambitious reduction targets emissions by 2030, and the IPCC findings are likely to feature prominently in the discussions.
The report says greenhouse gas emissions from human activities have caused global warming at a rate not seen in at least 2,000 years. Man-made climate change is estimated to be responsible for about 1.1 degrees Celsius of warming since 1850-1900, the first period with reliable measurements of global surface temperatures, the authors wrote.
What’s more, the report found that global temperatures are expected to exceed 2 degrees Celsius warming this century “unless there are sharp reductions in [carbon dioxide] and other greenhouse gas emissions occur in the decades to come.
“This report is a reality check,” Masson-Delmotte said in the statement. “We now have a much clearer picture of the past, present and future climate, which is essential for understanding where we are going, what can be done and how we can prepare.”
Climatologists have warned that the increase in average global temperatures should be limited to less than 2 degrees Celsius in order to avoid the most devastating effects of global warming. The 2-degree benchmark was set by climate negotiators in Copenhagen in 2009, but studies have increasingly shown that the target may already be out of reach.
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The new IPCC assessment goes further than any of the group’s previous reports in linking man-made climate change to the increase in extreme weather events around the world.
“It is practically certain that heat extremes (including heat waves) have become more frequent and intense in most land regions since the 1950s, while cold extremes (including cold waves) have become less frequent and less severe, ”the authors wrote, adding that warming is the“ main driver ”of these changes.
The report also details how rising ocean and surface temperatures will cause a myriad of physical climate changes – including drought, heat waves, heavy rains and coastal flooding – in different regions of the planet. .
The assessment is part of the IPCC’s latest summary on climate change, called the Sixth Assessment Report or AR6, which will be released next year. The full report consists of four sections: the report of Working Group I on the Science of Climate Change; the report of Working Group II on vulnerabilities and socio-economic impacts; the report of Working Group III on possible ways to mitigate climate change; and the Synthesis Report, which reviews the findings of all working groups and incorporates information relevant to decision makers.