By 2025, it is very likely that the levels of carbon dioxide in the atmosphere will be higher than they were during the warmer period of 3 million and 300 thousand years.
This situation foreshadows the exacerbation of the greenhouse phenomenon, global warming, and hence sea levels rise and coastal drowning.
These findings came in a new research conducted by a team from the University of Southampton, which was published in the Scientific Reports of the Nature Foundation on July 9, and reported by Phys.org.
Pleiocene fossils
The team studied the chemical composition of small pinhead-sized fossils collected from deep oceanic sediments in the Caribbean Sea. The team used these data to reconstruct knowledge of the concentration of carbon dioxide in the Earth's atmosphere during the Pliocene era, that is, about three million years ago when our planet was more than three degrees Celsius warmer than it is today with smaller polar ice caps and higher global marine levels.
Dr. Aline de la Vega, who led the study, said, "Knowledge of carbon dioxide during the geological past is of great importance because it tells us how the climate system, ice caps and sea level previously responded to its elevated levels."
"We studied this time lag with unprecedented detail, because it provides great contextual information for our current climate condition," he added.
Plankton shells
To determine the atmospheric carbon dioxide, the team used the isotopic composition of the boron component, which is naturally present as impurities in zooplankton shells called "foraminifera" or "forams" for short.
The plankton is about half a millimeter in size and gradually accumulates in huge quantities on the sea floor, and forms a treasure trove of information about Earth's past climate.
The isotopic composition of boron in its crust depends on the acidity (pH) of the seawater in which plankton lives.
Because there is a close relationship between the carbon dioxide in the atmosphere and the pH in seawater, this means that carbon dioxide can be calculated in the past from the accurate measurement of boron in ancient shells.
Amazing resemblance
One of the study's authors, Dr. Thomas Chuck, added that focusing on a warm historical period prior to when the sun was the same today gives us a way to study how the Earth is currently responding to the carbon dioxide effect.
"The surprising result that we found was that the warmest part of the Pliocene era contained between 380 and 420 parts per million carbon dioxide in the atmosphere. This is similar to today's value of about 415 parts per million, which indicates that we have already arrived," he said. To levels that were previously related to temperature and sea level much higher than today. "
He explained that currently, our carbon dioxide levels rise by about 2.5 parts per million annually, which means that by 2025 we will have exceeded anything we have seen in the past 3 million and 300 thousand years.
Unprecedented levels
For his part, Professor Gavin Foster, who also participated in the study, said, "The reason we do not see plosin-like temperatures and sea levels yet is that the Earth's climate takes some time until it reaches stability at the highest levels of carbon dioxide."
"After we exceed the pliocene levels of carbon dioxide by 2025, these levels will be unprecedented at any time during the past 15 million years, since the middle of the optimal myocene climate, a time that was warmer than pliocene," concluded Dr. de la Vega.