Scientists are warning that marine species are at risk of entering a phase of extinction unprecedented in human history.

A preliminary report arising from a ‘State of the Oceans’ workshop held at the University of Oxford in April, is the first ever to consider the cumulative impact of all pressures on the oceans. Considering the latest research across all areas of marine science, the workshop examined the combined effects of pollution, acidification, ocean warming, over-fishing and deoxygenation.

The scientific panel concluded that the combination of stresses on the ocean is creating the conditions associated with every previous major extinction of species in Earth’s history. And the speed and rate of degeneration in the ocean is far greater than anyone has predicted. As a result, although difficult to assess, the first steps to globally significant extinction may have begun with a rise in the extinction threat to marine species such as reef-forming corals.

“The findings are shocking,” says Dr Alex Rogers, Scientific Director of the International Programme on the State of the Ocean (IPSO) which convened the workshop. “As we considered the cumulative effect of what humankind does to the ocean, the implications became far worse than we had individually realized. This is a very serious situation demanding unequivocal action at every level. We are looking at consequences for humankind that will impact in our lifetime, and worse, our children’s and generations beyond that.”

Marine scientists from institutions around the world gathered at Oxford University under the auspices of IPSO and the IUCN. The group reviewed over 50 of the most recent research papers by world ocean experts and found firm evidence that the effects of climate change, coupled with other human-induced impacts such as over-fishing and nutrient run-off from farming, have already caused a dramatic decline in ocean health.

Increasing hypoxia and anoxia (absence of oxygen, known as ocean dead zones) combined with warming of the ocean and acidification are the three factors which have been present in every mass extinction event in Earth’s history.

There is strong scientific evidence that these three factors are combining in the ocean again, exacerbated by multiple severe stresses. The panel concluded that a new extinction event was inevitable if the current trajectory of damage continues, and could be said to have already begun.

The report concludes that “Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, overexploitation, pollution and habitat loss, the next globally significant extinction event in the ocean. It is notable that the occurrence of multiple high intensity- stressors has been a prerequisite for all the five global extinction events of the past 600 million years.”

It highlights these keypoints:
– Human actions have resulted in warming and acidification of the oceans and are now causing increased hypoxia.
– The speeds of many negative changes to the ocean are near to or are tracking worst-case scenarios. Some are as predicted but many are faster than anticipated and accelerating.
– The magnitude of the cumulative impacts on the ocean is greater than previously understood.
– Timelines for action are shrinking: the longer the delay in reducing emissions, the higher the annual reduction rate will have to be and the greater the financial cost.
– Resilience of the ocean to climate change impacts is severely compromised by other stressors from human activities, including fisheries, pollution and habitat destruction.
– The extinction threat to marine species is rapidly increasing.

The authors also give a solution, but comment that society’s values are a barrier to implementing what needs to be done.
– Reduce CO2 emissions
– Reduce fishing to sustainable levels
– Establish a global system of marine protected areas.
– Reduce pollution
– Avoid, reduce or at least strictly regulate oil, gas and mineral extraction
– Assess, monitor and control other uses of the marine environment such as renewable energy schemes
– Activities to proceed only if they are shown positively not to harm the ocean
– UN global body to ensure compliance with the UN Convention on the Law of the Sea

Further Reading:
Summary of the conclusions and recommendations of the international Earth system expert workshop on ocean stresses and impacts
Multiple ocean stresses threaten “globally significant” marine extinction