by The rate of increase of carbon dioxide in the atmosphere is currently 10 times faster than at any point in the last 50,000 years, research in Scotland and the US has shown.
A team of researchers led by the University of St. Andrews and Oregon State University undertook a detailed chemical analysis of ancient Antarctic ice (pictured below), revealing the stark results and the impact of human emissions.
The findings, published in the Proceedings of the National Academy of Sciences (PNAS), provide an important understanding of past periods of abrupt climate change on Earth and shed light on the potential impacts of climate change.
The rate of increase in carbon dioxide (CO2) was branded “unprecedented” and driven by human emissions.
When the gas enters the atmosphere, it contributes to the warming of the climate due to the greenhouse effect.
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In the past, the levels have changed due to ice age cycles and other natural causes, but today they are rising due to human emissions, according to scientists.
Dr. Kathleen Wendt, assistant professor in Oregon State University’s College of Earth, Ocean and Atmospheric Sciences (CEOAS) and lead author of the study, said: “Studying the past teaches us how the present is different. The rate of change of CO2 today is unprecedented.
“Our research has identified the fastest rates of past natural CO2 rise ever observed, and the rate occurring today, driven primarily by human emissions, is 10 times higher .”
Among the ice that has formed in the Antarctic over hundreds of thousands of years are ancient atmospheric gases trapped in air bubbles.
The scientists used ice samples, collected by drilling cores up to two miles deep, to analyze trace chemicals and make records of past climate.
The US National Science Foundation supported the ice core drilling and chemical analysis used in the study.
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Previous research has shown that during the last ice age, which ended about 10,000 years ago, there were several periods when carbon dioxide levels appeared to jump much higher than average, but the measurements detailed enough to reveal the full nature of the rapid changes. , limiting the ability of scientists to understand what was happening.
Dr Wendt said: “You probably wouldn’t expect to see that in the dead of the last ice age.
“But our interest was piqued, and we wanted to go back to those periods and make more detailed measurements to find out what was happening.”
Using samples from the West Antarctic Division ice core, Dr Wendt and his colleagues investigated what was happening during these periods, and identified a pattern that showed the jumps in carbon dioxide occurred alongside periods cold in the North Atlantic known as Heinrich Events which are associated with sudden. climate changes around the world.
Christo Buizert, associate professor in the College of Earth, Ocean and Atmospheric Sciences, and co-author of the study, said: “These Heinrich Events are truly remarkable. We think they caused the North American ice sheet to collapse significantly.
“This sets off a chain reaction of changes in the tropical monsoons, the westerly winds in the Southern Hemisphere and these big plumes of CO2 coming out of the oceans.”
Dr James Rae, from the School of Earth and Environmental Sciences at the University of St Andrews, and co-author of the study, said: “These Heinrich Events start a remarkable sequence of rapid climate changes around the world. They begin with a weakening of the North Atlantic circulation system, causing rapid cooling in Northwest Europe, expansion of sea ice from Scotland to New York, and disruption of tropical cyclones.
“Our paper shows that they change winds and circulation in the ocean around Antarctica, which releases CO2.”
During the greatest natural increases, carbon dioxide increased by about 14 parts per million in 55 years, and the jump occurred about once every 7,000 years or so – compared to current rates, when that increase takes only five to six years.
The evidence suggests that during periods of natural carbon dioxide rise in the past, the westerly winds that play an important role in deep ocean circulation also strengthened, resulting in the release of CO2 quickly from the Southern Ocean.
Other research has suggested that these westerlies will strengthen in the next century due to climate change.
The results suggest that if that happens, it will reduce the Southern Ocean’s ability to absorb human-generated carbon dioxide, the researchers noted.
Dr Wendt said: “We rely on the Southern Ocean to absorb some of the carbon dioxide we emit, but rapidly increasing southerly winds weaken its ability to do so.”
