Climate change: Oceans running out of oxygen as temperatures rise
“Climate change and nutrient pollution are driving the oxygen from our oceans, and
threatening many species of fish.
While nutrient run-off has been known for decades, researchers say that climate change is
making the lack of oxygen worse. Around 700 ocean sites are now suffering from low oxygen,
compared with 45 in the 1960s.
Researchers say the depletion is threatening species including tuna, marlin and sharks.
The scientists estimate that between 1960 and 2010, the amount of the gas dissolved in the
oceans declined by 2%. That may not seem like much as it is a global average, but in some tropical
locations the loss can range up to 40%.
If countries continue with a business-as-usual approach to emissions, the world's oceans are
expected to lose 3-4% of their oxygen by the year 2100.
This is likely to be worse in the tropical regions of the world. Much of the loss is expected in
the top 1,000m of the water column, which is richest in biodiversity.
"Ocean oxygen depletion is menacing marine ecosystems already under stress from ocean
warming and acidification," said Dan Laffoley, also from IUCN and the report's co-editor. "To stop
the worrying expansion of oxygen-poor areas, we need to decisively curb greenhouse gas emissions
as well as nutrient pollution from agriculture and other sources."”
(Adapted from https://www.bbc.com/news/science-environment-50690995)
In the text, the word “”greenhouse”, in “greenhouse gas emissions”, means, in Portuguese: