This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Marine heat waves are a consequence of climate change and are increasingly altering marine and coastal regions worldwide. An international study led by the Helmholtz-Zentrum Hereon now shows that many coastal seas absorb more CO₂ from the atmosphere during these extreme events than under normal conditions.
The effect is particularly pronounced in polar and subpolar shelf seas of the Northern Hemisphere, where sea ice is declining as temperatures rise. The study investigates a specific factor that can help improve the assessment of the highly complex climate processes on Earth. The work was recently published in the journal Nature Communications.
Researchers define marine heat waves as periods during which seawater temperatures remain higher than 90% of the temperature values measured for the same region during a 30-year reference period for at least five days. They can last for several weeks. Until now, scientists assumed that warmer seawater can absorb less CO₂ because the physical solubility of gases decreases with increasing temperature.
Previous studies from the open ocean clearly show a corresponding weakening of natural CO₂ uptake during heat waves. In polar and subpolar shelf seas, however, the Hereon study shows the opposite effect. Shelf seas are shallow marine areas along the edges of continents, such as regions of the Northwest Pacific and North Atlantic.
They account for about 7% of the global ocean area. In polar regions, marine heat waves lead to a reduction in sea ice. As a result, the area of open water can increase by up to 30%.
A continuous exchange of gases takes place between the atmosphere and the ocean. Water absorbs, among other gases, CO₂ from the air. A thick layer of sea ice acts as a barrier and inhibits this exchange.
Extract — continue reading at the source.
