Arctic Warming: Some Effects May Remain Irreversible Despite Reduced Carbon Dioxide Levels

Even if atmospheric carbon dioxide returns to pre-industrial levels and the global temperature decreases, the Arctic is projected to warm by approximately 1.5 degrees Celsius.

It is also expected that the region will receive about 0.1 millimeter of extra precipitation daily, regardless of the implementation of large-scale carbon dioxide removal (CDR) strategies.

“These findings emphasize the irreversible aspect of climate change in the Arctic, even with aggressive CDR efforts,” the researchers stated in their publication.

Current atmospheric CO2 levels are roughly 1.5 times greater than pre-industrial levels, resulting in a warming of 3°C or more. A study published in March revealed that even if extra carbon dioxide were removed, sea ice coverage would still average 1 million square kilometers less.

In a new investigation, researchers led by Xiaodong from the Institute of Atmospheric Physics in Beijing utilized 11 distinct climate models to assess the likelihood of continued Arctic warming. The findings also indicate that precipitation is likely to increase, according to Michael Meredith from the British Antarctic Survey, who was not part of the study.

The primary reason for this persistent warming is that oceans, which have absorbed 90% of the heat from global warming, will continue to warm the Arctic for centuries, even when atmospheric temperatures decrease. This situation will likely be amplified by feedback mechanisms, such as diminishing sea ice, which causes the open ocean to raise air temperatures.

“Even if the atmosphere continues to cool, the oceans will lag behind and counteract this trend,” Meredith remarked.

Many experts express skepticism about whether CDR methods, including tree planting and mechanical CO2 extraction, can significantly lower atmospheric CO2 levels due to the financial and energy challenges, a process that could take thousands of years.

Dong et al. examined a theoretical scenario where atmospheric CO2 levels quadrupled from pre-industrial amounts over 140 years, decreased for another 140 years, and then remained at pre-industrial levels for 60 additional years.

The study also reviewed two potential real-world climate scenarios: one in which humanity immediately reduces emissions, and another where emissions remain high but CDR efforts ramp up quickly starting in 2070. In these scenarios, similar to the theoretical model, the Arctic was found to be approximately 1.5 degrees Celsius warmer with precipitation increasing by an additional 0.1 mm per day by 2100.

The models forecast a decrease in temperatures and precipitation in the waters just south of Greenland and Iceland, contrasting with other regions in the Far North. This suggests a decline in the Atlantic Meridional Overturning Circulation (AMOC), which is responsible for transporting warm surface water from the tropics to this area. This current is already weakening as global ocean temperatures rise, a trend that might lead to colder winters in Europe over time.

Climate-related effects, such as thawing permafrost and melting of the Greenland ice sheet, are likely to persist but were not included in this study’s models.

“The Greenland ice sheet is expected to behave as observed, meaning it will continue to lose mass and contribute to sea level rise,” stated Mark Selles from the US National Snow and Ice Data Center.

While the study indicates that the Arctic will remain warm for centuries, it is anticipated that it will eventually cool over the course of many more centuries or even millennia.