(© Quality Stock Arts - stock.adobe.com)
CORVALLIS, Ore. – The amount of carbon dioxide in Earth’s atmosphere is increasing at a speed that has never been seen before in modern times, a dire new study warns. Specifically, a detailed chemistry analysis of Antarctic ice shows the rate of atmospheric carbon dioxide is rising 10 times faster than at any other point in the last 50,000 years.
Researchers from Oregon State University say the findings can provide new insight into how climate change has affected Earth in the past and what it might mean for the planet in the future.
“Studying the past teaches us how today is different. The rate of CO2 change today really is unprecedented,” says Kathleen Wendt, an assistant professor in Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences and the study’s lead author, in a media release. “Our research identified the fastest rates of past natural CO2 rise ever observed, and the rate occurring today, largely driven by human emissions, is 10 times higher.”
Carbon dioxide is a greenhouse gas that occurs naturally in the atmosphere. When carbon dioxide builds up in the atmosphere, it contributes to the greenhouse effect — gases trap heat in the atmosphere, causing heat to reflect back to Earth instead of venting out into space. This trapped heat further warms the Earth up. In the past, carbon dioxide levels in the atmosphere have fluctuated because of ice age cycles and other natural events. Fast forward to today, and carbon dioxide levels have risen to unprecedented levels because of human-created emissions.
One of the best ways to measure carbon dioxide levels from the past is to examine ancient slabs of ice. Antarctic ice has built up over hundreds of thousands of years and contains ancient atmospheric gasses trapped in air bubbles. In the study, researchers drilled for ice core samples up to two miles deep to analyze trace chemicals and build records of past climate activity.
Previous research on the last ice age, which ended about 10,000 years ago, showed several periods where carbon dioxide levels soared higher than average. However, the measurements were incomplete and could not explain what caused this escalation in carbon dioxide.
“You probably wouldn’t expect to see that in the dead of the last ice age,” says Wendt. “But our interest was piqued, and we wanted to go back to those periods and conduct measurements at greater detail to find out what was happening.”
The ice core samples in the current study came from the West Antarctic Ice Sheet Divide. Study authors found a pattern that showed the increases in carbon dioxide levels occurred alongside North Atlantic cold intervals called Heinrich Events, which were linked to abrupt climate shifts around the world.
“These Heinrich Events are truly remarkable,” says Christo Buizert, an associate professor in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University and co-author of the study. “We think they are caused by a dramatic collapse of the North American ice sheet. This sets into motion a chain reaction that involves changes to the tropical monsoons, the Southern hemisphere westerly winds and these large burps of CO2 coming out of the oceans.”
In one of the largest jumps in carbon dioxide levels, carbon dioxide soared by about 14 parts per million in 55 years. The jumps used to happen once every 7,000 years. Nowadays, it takes five or six years for carbon levels to soar.
While today’s carbon rates are due to fossil fuels and human emissions, westerly winds seemed to be the cause behind rising carbon dioxide levels in the past. These winds would help strengthen circulation in the deep ocean, leading to a fast release of carbon dioxide from the Southern Ocean.
The Southern Ocean helps absorb human-generated carbon dioxide. However, if westerly winds get stronger, the ocean will be less capable of trapping carbon dioxide. Other bodies of research predict that western winds are expected to get stronger over the next century due to climate change.
The study is published in the Proceedings of the National Academy of Sciences.
