Crucial global climatic system could face tipping point in two years

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Crucial global climatic system could face tipping point in two years

By Nick O'Malley

A major climatic system that helps regulate weather in Europe and North America could collapse as soon as 2025 due to greenhouse gas emissions, far sooner than United Nations scientists had predicted, according to a paper published overnight in the leading scientific journal Nature Communications.

Danish researchers Peter Ditlevsen and Susanne Ditlevsen analysed sea surface temperatures in the North Atlantic between 1870 and 2020, and say they have found early warning signals of a big change to the system, which might suggest it could shut down as early as 2025, and no later than 2095.

A man tries to extinguish a fire with a hose near Loutraki 80 kilometres west of Athens.

A man tries to extinguish a fire with a hose near Loutraki 80 kilometres west of Athens.Credit: AP Photo/Petros Giannakouris

The last time this kind of abrupt climate change occurred average northern hemisphere temperatures fluctuated by 10 to 15 degrees over a decade.

By comparison, the heatwaves causing havoc across the northern hemisphere over recent weeks are thought to have been exacerbated by global warming of about 1.2 degrees since humans began releasing greenhouse gasses into the atmosphere at the start of the industrial revolution.

The potential collapse of the AMOC (Atlantic Meridional Overturning Circulation) had been considered in recent United Nations climate assessments, but it was viewed as unlikely to occur this century.

The authors do not make assumptions about the cause of the AMOC change but point out that atmospheric carbon dioxide concentrations have increased almost linearly within the time period studied.

The findings on the North Atlantic come as new reports show that winter sea ice coverage in the Antarctic has reached historic lows.

According to the University of Colorado Boulder’s National Sea and Ice Data Centre, “Antarctic ice extent as of mid-July is more than 2.6 million square kilometres below the 1981 to 2010 average”.

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The heatwaves that have hit China, Europe and North America would once have been extremely rare events but are now far more common due to human-induced climate change, a second report published this week has found.

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An analysis by the World Weather Attribution network, which conducts rapid analyses to determine how the warming atmosphere influences extreme weather events, has found that recent extreme temperatures can now be expected once every 15 years in the US-Mexico region, once every 10 years in Southern Europe, and once in five years for China.

Without human-induced climate change, the heatwave in China would have been about a 1 in 250-year event, while the maximum heat likely in July 2023 would have been virtually impossible to occur in the US-Mexico region and Southern Europe, the scientists found.

According to the analysis, the scientists found that if there is no rapid decarbonisation of the world’s economy, the incidence, extent and duration of extreme heatwaves will continue to increase.

“A heatwave like the recent ones would occur every two to five years in a world that is 2 degrees warmer than the pre-industrial climate,” it says.

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