This Ancient Ice Block Unveils Current CO2 Levels

Although there’s increasing evidence suggesting that we’re experiencing unparalleled levels of atmospheric greenhouse gases, our limited historical understanding has impeded our ability to contextualize current CO2 emissions over the long term. What if we could utilize the Earth’s natural historical records to fill in these crucial gaps?

In a daring move, researchers from Oregon State University (OSU) and the University of St Andrews, in collaboration with the US National Science Foundation, have embarked on a groundbreaking study.

They have unveiled a 50,000-year history of atmospheric carbon dioxide by analyzing minuscule bubbles preserved in Antarctic ice, which have remained frozen beneath the Earth’s surface for millennia.

Understanding the Unprecedented CO2 Fluctuations Today

“Exploring the past provides insights into the uniqueness of the present,” commented Kathleen Wendt, an assistant professor at OSU and the lead author of the study. “The pace of CO2 fluctuation today truly stands out as unparalleled.”

By examining frozen samples from the West Antarctic Ice Sheet (WAIS) Divide ice core, retrieved through drilling two miles (3.2 km) deep, the team conducted chemical analyses on the minute pockets of preserved gases within the ice cores to elucidate the historical shifts in atmospheric CO2 levels spanning many millennia.

What the researchers discovered was that although there have been periods of heightened CO2 levels in the atmosphere well beyond the “normal” range, those levels are dwarfed by the current situation exacerbated by anthropogenic greenhouse gas emissions.

Historical CO2 Fluctuations

Over the span of 50,000 years, the team observed that the natural fluctuations in atmospheric CO2 levels increased by an estimated 14 parts per million every 7,000 years or so. In contrast, today, CO2 levels surge by the same amount every five to six years.

In essence, the rate of CO2 increase now is tenfold faster than at any other point in the past 50,000 years.

“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,” stated Wendt.

The team’s analysis has provided a comprehensive, long-term depiction of the Earth’s historical atmospheric CO2 fluctuations, which also revealed spikes coinciding with North Atlantic cold intervals, known as Heinrich events, associated with sudden and significant climate changes.

“These Heinrich events are truly remarkable,” remarked Christo Buizert, an associate professor at OSU and co-author of the study. “We believe they are caused by a dramatic collapse of the North American ice sheet, triggering a cascade of changes to the tropical monsoons, the Southern Hemisphere westerly winds, and significant releases of CO2 from the oceans.”

Strengthening Westerly Winds and Reduced CO2 Absorption

Existing climate data indicates that these westerly winds are likely to become stronger and more frequent as the planet warms, potentially reducing the Southern Ocean’s capacity to absorb and contain human-generated CO2. This feedback loop is concerning for scientists as the planet continues to warm.

“We rely on the Southern Ocean to absorb part of the carbon dioxide we emit, but rapidly increasing southerly winds weaken its ability to do so,” explained Wendt, who believes that historical insights will enhance our understanding of Earth’s processes and improve our intervention strategies.

“The rate and magnitude of atmospheric CO2 rises resolved in this study provide critical insights into carbon-cycle variability during abrupt climate shifts and highlight the possibility that the modern-day Southern Ocean carbon sink could weaken in response to ongoing poleward enhancement of the Southern Hemisphere westerlies,” concluded the researchers.

Read the original article on: New Atlas

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