While part of the world tries to limit global warming to within the threshold of 1.5 degrees above pre-industrial temperatures, as also required by the 2015 Paris Agreement, it is possible that in reality this limit has already been exceeded: this would be indicated by the sponges that inhabit the oceans around the Caribbean, which constitute natural 'archives' of ocean temperatures, whose data were analyzed in a study published in the journal Nature Climate Change and led by the University of Western Australia.
The findings show that even the goal of keeping warming below 2 degrees could be exceeded by the end of the decade.
Coral sponges, also called sclerosponges, are fundamental for the functioning of coral reefs and have a calcareous skeleton in which all climate changes are recorded.
Researchers led by Malcolm McCulloch then collected samples in the eastern Caribbean, where the natural variability of temperatures is lower than in other places, to reconstruct the climate history of the last 300 years.
The data obtained suggest that warming linked to human activities began as early as the mid-1860s, i.e. about 80 years earlier than what the measurements made on the sea surface using instruments show.
Therefore, in the 1961-1990 reference period that is used to calculate any anomalies, the temperatures of the uppermost layer of the oceans had already increased by 0.9 degrees compared to the corrected pre-industrial period, a value greater than the 0.4 degrees so far esteemed.
This implies that global temperatures may already be above the 1.5 degree mark and that the 2 degree mark is fast approaching.
According to the authors of the study, in fact, between 2018 and 2022 the ocean surface may have recorded an increase of 1.7 degrees compared to pre-industrial temperatures.
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