According to Malcolm McCulloch, a coral reef researcher at the Ocean Institute at the University of Western Australia in Crawley and lead author of the new study, the temperature has been underestimated by about half a degree. nature-in.
The calculations so far have used global average temperature values for the pre-industrial period between 1850 and 1900, which are the oldest instrumental sea surface temperature data measured on ships. But according to Malcolm McCulloch, those marine sponges that were already around in the 18th century and are still with us today are more reliable indicators of temperature.
He and his colleagues analyzed the composition of strontium and calcium in a 300-year-old calcium carbonate skeleton of Ceratoporella nicholsoni, a type of coral-like sponge that lives off the coast of Puerto Rico, and which is affected only by changes in water temperature. Sponges live at depths ranging from 33 to 91 metres, which is important because sea surface temperatures can vary greatly,
But the data for this intermediate depth are representative of the entire system down to a few hundred metres, and are in equilibrium with the atmospheric temperature.
This part of the Caribbean Sea is relatively protected from large ocean currents and major weather events (such as El Niño), which means that water temperatures do not fluctuate as much as in other ocean areas. According to the sponge skeletons, the planet began warming as early as the mid-1860s. During the relatively stable period between 1700 and 1860, global sea surface temperatures varied by less than 0.2°C.
Malcolm McCulloch and colleagues calculate that the global temperature may actually have been about 0.5 degrees Celsius higher than previously estimated, and global warming exceeded 1.5 degrees in the period 2010-2012. The research team verified the accuracy of temperature data from the sponges by comparing them to global average temperature records from 1964 to 2012.
However, many climate scientists are skeptical about coral scales, because their temperature may not always be constant. A global investigation into global warming will likely require additional data from around the planet and from more sources.
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