By 2025, Earth's CO2 Levels Will Reach All-Time High In Past 3.3 Million Years
It would seem that COVID-19 lockdown has decreased carbon dioxide levels in the world
Despite a decline in carbon dioxide emissions worldwide during the COVID-19 pandemic, atmospheric CO2 is set to reach an all time high in 2025 since the last 3.3 million years, a new study warns.
Jim Salinger, Lisa Alexander
The new research by a team from the University of Southampton is titled "Atmospheric CO2 during the Mid-Piacenzian Warm Period and the M2 glaciation" and has now been published in Nature Scientific Reports.
To come to the drastic conclusion, the team studied the chemical composition of tiny fossils present deep in the ocean sediments of the Caribbean Sea.
The scientists used the findings from the minuscule pieces of fossils to reconstruct the concentration of CO2 in Earth's atmosphere during the Pliocene epoch, a geologic timescale extending from 5.332 million to 2.588 million years before present.
(Representative Image: Reuters)
During the Pliocene epoch, Earth was more than 3¡ãC warmer than it is at present. As a result, the planet had smaller polar ice caps and higher global sea-levels. Studying the role of atmospheric CO2 in shaping the climate at the time can help us predict what to expect with such CO2 levels in the future.
As Dr. Elwyn de la Vega, who led the study, said: "Knowledge of CO2 during the geological past is of great interest because it tells us how the climate system, ice sheets and sea-level previously responded to the elevated CO2 levels. We studied this particular interval in unprecedented detail because it provides great contextual information for our current climate state."
The CO2 experiment
In order to find out the atmospheric CO2 at the time, the team studied impurities in the shells of zooplankton called foraminifera or 'forams'. These forams are around half a millimeter in size and are found in huge quantities on the seabed.
Scientists studied the isotopic composition of the element boron found in their shells. The acidity (pH) of the seawater in which the forams live hints at the atmospheric CO2 present. CO2 presence in the past can be calculated from measurement of the boron in these ancient shells.
Impact of CO2 levels on global warming
(Representative Image: Reuters)
Dr. Thomas Chalk, a co-author of the study, said: "A striking result we've found is that the warmest part of the Pliocene had between 380 and 420 parts per million CO2 in the atmosphere. This is similar to today's value of around 415 parts per million, showing that we are already at levels that in the past were associated with temperature and sea-level significantly higher than today.¡±
The study even predicts what¡¯s to come. ¡°Currently, our CO2 levels are rising at about 2.5 ppm per year, meaning that by 2025 we will have exceeded anything seen in the last 3.3 million years," adds Dr Chalk.
We do not see similar sea levels and global warming yet though. Professor Gavin Foster, also a part of the study, explains this: "The reason we don't see Pliocene-like temperatures and sea-levels yet today is because it takes a while for Earth's climate to fully equilibrate (catch up) to higher CO2 levels and, because of human emissions, CO2 levels are still climbing. Our results give us an idea of what is likely in store once the system has reached equilibrium."
