Through a simulation of a worst-case emissions scenario, the study revealed that the maximum CO2 absorption by the oceans would be reached by 2100 and could drop to half its current effectiveness by 2300.
The decreased absorption of CO2 is attributed to the presence of a thin layer of low-alkalinity water that hampers the ocean's capacity to absorb carbon dioxide. Alkalinity, a chemical property, affects the amount of carbon dioxide that can be dissolved in seawater.
Although the chances are low due to global efforts to limit greenhouse gases, the study discovered a previously unrecognized tipping point that, if reached, could remove a significant check on global warming, according to the researchers.
Megumi Chikamoto, a research fellow at the University of Texas Institute for Geophysics, emphasized that we must consider these adverse scenarios to understand the impact of our CO2 emissions on the oceans over the next two centuries. The study was published in the Geophysical Research Letters journal.
The University of Texas Institute for Geophysics studied the effects of potential future warming on the Gulf of Mexico in 2017. Their research indicated potential chemical changes in the ocean's surface that could boost climate change. Credit: Jackson School of Geosciences/Tiannong "Skyler" Dong
According to current estimates, the oceans are absorbing around one-third of CO2 emissions from human activities. Previous simulations had demonstrated that the rate of absorption is diminishing, yet none of them had taken into account alkalinity as a potential factor. To reach their conclusion, the researchers modified components of a 450-year simulation until they identified alkalinity as the cause for the slowing.
Research has shown that climatic shift can cause an increase in rainfall and decelerate ocean currents. This leads to the formation of a warm layer of fresh water on the surface of the ocean that is not easy to combine with the cooler, more alkaline waters underneath. As the surface layer becomes more saturated with CO2, its alkalinity drops, decreasing its capacity to take in the gas. This creates a surface layer that serves as a hindrance for the absorption of CO2. Consequently, less of the greenhouse gas goes into the ocean and more is retained in the atmosphere, causing faster warming that maintains and intensifies the low-alkalinity surface layer.
Pedro DiNezio, an affiliate researcher at the University of Texas Institute for Geophysics and associate professor at the University of Colorado, pointed out that this discovery is a stark reminder that the world must lower its carbon dioxide emissions in order to prevent surpassing this tipping point, as well as numerous others.
He stated that it is critical to steer clear of the various possible catastrophes that could arise, such as the melting of ice sheets. To determine if the alkalinity mechanism is activated under less extreme emissions, he said the following step is to figure this out.
Nikki Lovenduski, a professor at the University of Colorado who was part of the Intergovernmental Panel on Climate Change 2021 climate report, noted that this research would assist in more accurate forecasting of future climate change.
The researcher stated that there may be additional components contributing to the climate change issue that are presently unknown. Nevertheless, the investigation that uncovered an ocean climate feedback mechanism is likely to spark further study of the carbon cycle, historical climate changes, and possibly even create options for approaching any upcoming issues.
In an investigation of ocean carbon uptake, Megumi O. Chikamoto, Pedro DiNezio and Nicole Lovenduski have discovered in their article, "Long-Term Slowdown of Ocean Carbon Uptake by Alkalinity Dynamics" (9 January 2023, Geophysical Research Letters; DOI: 10.1029/2022GL101954), a long-term slowdown in the process.
Funding for the research was provided by the National Science Foundation.
Post a Comment