Global warming is making the oceans more stable, raising surface temperatures and reducing the carbon they can absorb, according to research released Monday by climate scientists who warned the findings have “profound and troubling” implications.
Human-caused climate change has increased surface temperatures across the planet, leading to atmospheric instability and amplifying extreme weather events, such as storms.
But in the oceans, higher temperatures have a different effect, slowing the mixing between the warming surface and the cooler, oxygen-rich waters below, the researchers said.
This ocean “layering” means shallower water is rising to the surface carrying oxygen and nutrients, while surface water absorbs less atmospheric carbon dioxide to bury deep.
In a report published in the journal Nature climate change, the international team of climate scientists said they found that global stratification increased by a “substantial”
Most of this stabilization occurred towards the surface and was largely attributed to temperature increases.
They said this process is also exacerbated by the melting of sea ice, meaning that more fresh water – which is lighter than salt water – also accumulates on the ocean’s surface.
Study co-author Michael Mann, a professor of climate science at Pennsylvania State University, said in a comment posted in Newsweek that “the seemingly technical discovery has profound and troubling implications.”
These potentially include driving “more intense and destructive hurricanes” as the ocean surface warms.
Mann also pointed to a reduction in the amount of CO2 absorbed, which could mean that carbon pollution builds up faster than expected in the atmosphere.
He warned that sophisticated climate models often underestimate the stratification of the oceans and may even underestimate its impact.
With warmer upper waters receiving less oxygen, there are implications for marine life as well.
By absorbing a quarter of man-made CO2 and absorbing more than 90% of the heat generated by greenhouse gases, the oceans keep the population alive, but at a terrible cost, according to the Intergovernmental Panel for Climate Change (IPCC).
The seas have turned acid, potentially undermining their ability to absorb CO2. Warmer surface water has expanded the strength and reach of deadly tropical storms.
Marine heatwaves are sweeping away coral reefs and accelerating the melting of glaciers and ice sheets that cause sea level rise.
Last year, research published in Proceedings of the National Academy of Sciences of the United States calculated that climate change would empty the ocean of nearly a fifth of all living creatures, measured by mass, by the end of the century.
© Agence France-Presse