Oops, scientists may have miscalculated the timeline for global warming

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  • The Paris Climate Accords in 2015 set an ambitious (and necessary) target of holding global temperatures to 1.5°C above pre-industrial temperatures. But a new study says we may have crossed that threshold several years ago.

  • A new study by the Ocean Institute at the University of Western Australia studied long-lived Caribbean sponges and established a timeline of ocean temperature dating back to the 18th century.

  • While the study claims we exceeded 1.5°C in 2020, other scientists question whether data from just one part of the world is enough to capture the enormous thermal complexity of our oceans.


Whatever your position Climate change (It’s true, let’s move on), it’s impossible to ignore the near-universal call to action to “hold temperatures to within 1.5 degrees Celsius of pre-industrial levels.” Over the past few years, the somewhat bureaucratic phrase has become a rallying cry for climate enthusiasts.

This ambitious goal appeared for the first time yet Paris climate agreementIt describes a kind of climate threshold – if we exceed a long-term average increase in temperature of 1.5°C, and maintain these levels for several years, we will do some serious damage to ourselves and our environment.



Well, a new paper from the Ocean Institute at the University of Western Australia has some bad news: the world may have crossed that threshold. Four years ago. Published in the magazine The nature of climate changeThe paper reached this conclusion through an unexpected route: analyzing six hard sponges, a type of sponge Sea sponge That cling to underwater caves in the ocean. These sponges are commonly studied by climate scientists and are referred to as “Natural archives“Because they grow very slowly. Like a fraction of a millimeter per year slowly. This allows them to essentially preserve climate data in their limestone structures, which is not very different from tree rings or ice cores.”

By analyzing the ratios of strontium to calcium in these sponges, the team was able to effectively calculate water temperatures dating back to the year 1700. The sponge’s aquatic habitat in the Caribbean is also a plus, as are the major oceans. Currents Does not corrupt or distort temperature readings. This data could be particularly useful, since direct human measurement of sea temperature dates back to about 1850, when sailors dipped buckets into the ocean. This is why the Intergovernmental Panel on Climate Change (IPCC) uses 1850 and 1900 as a pre-industrial baseline. According to the Grist website.

“The big picture is that Global Warming Malcolm McCulloch, lead author of the study, said the clock on cutting emissions to reduce the risks of dangerous climate change has been advanced by at least a decade. News agency. “Basically, we’re running out of time.”



The study concludes that global warming began nearly 80 years earlier than the Intergovernmental Panel on Climate Change estimates, and that we have already exceeded 1.7 degrees Celsius in 2020. This is a big moment, if true, but some scientists are skeptical. One of these scholars, Talk to LiveScienceHe said it was “naive to claim that the instrumental record is wrong based on ancient sponges from one region of the world.” world…It honestly doesn’t make sense to me. Other experts He would like to see more data Before completely upending climate targets set by the Intergovernmental Panel on Climate Change, which says the Earth is currently hovering at a long-term temperature change of about 1.2°C.

Unfortunately, even if Sponge If we are wrong, there is mounting evidence that we are crossing the 1.5 degree threshold as we speak. This January was the hottest on record, reaching 1.7 degrees above pre-industrial temperatures. according to new world, this means that we have been above 1.5 degrees of change for at least a year. It does not take the longer term average above the 1.5 line, but it is definitely a sign that we are quickly approaching.

Regardless of the percentage, one thing is certain: climate change is a systemic crisis. In order to save the planet for future habitability, Humans We need to reduce emissions immediately – after all, sea sponges are telling us so.

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(tags for translation)University of Western Australia Ocean Institute

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