The next decade will be crucial in combating declining ocean oxygen levels which are threatening sealife and could eventually put humankind at risk, according to experts.

The new study, which is the biggest report of its kind, was carried out by the International Union for the Conservation of Nature (IUCN).

Its findings were presented in Madrid, Spain, at the global UN Climate Change conference earlier today.

The researchers found that climate change and pollution were the main causes of oxygen loss, also known as deoxygenation.

The next decade will be crucial in combating declining ocean oxygen levels which are threatening sealife and could eventually put humankind at risk, according to experts. pictured: Reef at Gray's Reef National Marine Sanctuary

There are thought to be more than 1,000 dead zones in the ocean, where deoxygenation has taken hold, with currently around 700 already confirmed.

But prior to 1960 there were just 45, showing that the areas completely depleted of oxygen have quadrupled over the past five decades.

Peter Thomson, the UN's special envoy for oceans, said in the study: 'I believe the report demonstrates that the next 10 years will be more important for humanity than the last hundred, indeed thousands of years have been for our survival.'

The report went on to say that deoxygenation is now altering the balance of marine life as it favours the species which do not require as much oxygen to thrive.

These include jellyfish, microbes and some squid.

Those particularly at risk include tuna, marlin and sharks because their size means that they have higher energy demands to their marine companions.

It seems as though these species are in turn moving to shallower areas where they become much more vulnerable to over-fishing.

The report went on to say that deoxygenation is now altering the balance of marine life as it favours the species which do not require as much oxygen. This puts species such as tuna (stock image), marlin and sharks at risk

There were 67 experts from 17 countries who were involved in the study.

IUCN acting director general, Dr Grethel Aguilar, said: 'With this report, the scale of damage climate change is wreaking upon the ocean comes into stark focus.

'As the warming ocean loses oxygen, the delicate balance of marine life is thrown into disarray.

'The potentially dire effects on fisheries and vulnerable coastal communities mean that the decisions made at the ongoing UN Climate Change Conference are even more crucial.'

Oceans are expected to lose up to four per cent of their oxygen by the end of the century and the report warns that the ripple effect could prove costly for millions of people.

Isabella Lovin, Sweden's minister for environment and climate, wrote in the report: 'Whilst we have known about dead zones in the ocean for many decades, ocean warming is now expected to further amplify deoxygenation across great swathes of the ocean.

'Ocean deoxygenation is putting life at risk. Failing to protect our ocean will jeopardize humankind, as our security, economy and our very own survival depends on it.'



Three of this year's Nobel Prize laureates recently spoke out about the need to address climate change during a news conference in Sweden.

