Oceans are running out of oxygen at an unprecedented rate as a result of the climate emergency, scientists have warned.
A large number of vital ecosystems are in danger of collapse, with sharks, tuna, marlin and other large fish species found to be at particular risk.
Dead zones – where oxygen is effectively absent – have quadrupled in the last half-century, and there are at least 700 areas where oxygen is at dangerously low levels, up from 45 when research was first undertaken in the 1960’s.
The International Union for the Conservation of Nature presented the findings on Saturday, December 7, at the UN Climate Conference in Madrid, where officials are negotiating ways to tackle the climate crisis.
Grethel Aguilar, the acting director general of the International Union for Conservation of Nature (IUCN), said the health of the oceans needs to be a key consideration in the talks. ‘As the warming ocean loses oxygen, the delicate balance of marine life is thrown into disarray,’ she said, as per The Guardian.
The director general continued:
The potentially dire effects on fisheries and vulnerable coastal communities mean that the decisions made at the conference are even more crucial.
Some ocean areas are naturally lower in oxygen than others, and these areas are even more susceptible to damage when their oxygen levels are depleted further, the report’s authors said.
Species that can more easily tolerate low oxygen levels – such as jellyfish, some squid and marine microbes – can flourish at the expense of fish, upsetting the balance of ecosystems even further.
And while all fish need dissolved oxygen, the biggest species are particularly vulnerable to depleted oxygen levels because they need much more of it to survive. Evidence shows these depleted levels are forcing them to move towards the surface and to shallow areas of the sea, where they are more vulnerable to fishing.
In recent years, the threat to the oceans has become more severe due to climate change and global heating. As more carbon dioxide is released – enhancing the greenhouse effect – much of the heat is absorbed by the oceans, with these warmer waters holding less oxygen.
In fact, oceans are expected to lose around 3-4% of their oxygen by the end of this century.
Changing the outcome of what will happen to the oceans is the responsibility of the world’s political leaders, which is why the report has been launched at the UN Climate Conference.
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