Oceans to enter Holocene Mass Extinction

The cumulative effect of environmental threats like climate change, ocean acidification and overfishing, brings the world’s interconnected ocean close to a phase of extinction of marine species that is ‘globally significant’ and unprecedented in human history, an international panel of marine scientists states.

On Monday the International Programme on the State of the Ocean (IPSO) has released a preliminary report looking into the state of ongoing research, which concludes:

  • The cumulative threats create conditions comparable to those during the Earth’s big marine mass extinctions.
  • The speed and rate of degeneration in the ocean is far faster than anyone has predicted.
  • Many of the negative impacts previously identified are greater than the worst predictions.
  • Although difficult to assess because of the unprecedented speed of change, 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.

In our collective understanding we are slowly getting to the essence of the environmental problems of our time. In the ‘Anthropocene’ the world’s entire ecosystem is influenced by just one species – not by one of its actions, but by the culmination of them all.

And this understanding may also have implications for our attempt to abate our planet’s sustainability crises – as evidence is mounting we may need to adopt the same holistic view to these problems as to their solutions. Multiple causes demand integrated strategies.

Micro: the bees

On a microscale we use CCD as our textbook example. It’s not the environmental disturbance around one single virus or one invasive mite. It’s not one insecticide we abundantly spray, not just the decline in flower biodiversity that modern agriculture causes, or the high-frequency jamming of millions of cell phones. It is all of such stresses combined that inflate the problem to stretch beyond the natural regenerative capacity of the dynamic equilibrium that any ecosystem is, and lead to a collapse, and escalating damage.

Macro: marine life

And on a macroscale we can draw the parallel to the world’s one single ocean, the IPSO report indicates. Because the world’s marine ecosystems suffer the cumulative effects of pollution, acidification, ocean warming, overfishing and hypoxia the associated ecological damage is no longer limited to densely populated coastlines or popularly consumed fish species.

Dividing moment in planetary history

In fact, the world’s interconnected ocean as a whole is sliding into the Holocene Mass Extinction, the geological event that some scientists use to divide the boundary of the Holocene and the Anthropocene epoch, the one that’s named after us – and that may still be visible in the Earth’s geological record hundreds of millions of years from now, because species of fish, shellfish, crustaceans and other marine life, that were abundant on this planet for millions of years – suddenly, in less than the blink of a geologist’s eye, vanished – for good.

It means we humans are currently writing planetary history – and not really to anyone’s advantage.

Three death signs: boiling, dissolving, suffocating

The IPSO scientists state “increasing hypoxia (low oxygen levels) 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 stressors.

‘Worse than PETM extinction’

As example the scientists make a comparison with the PETM extinction event, the methane-fed climate event 55.8 million years ago we recently reported on:

“The rate at which carbon is being absorbed by the ocean is already far greater now than at the time of the last globally significant extinction of marine species, some 55 million years ago, when up to 50% of some groups of deep-sea animals were wiped out.” [“Indeed,” we hear our regular visitors say, “10 times as fast”.]

The researchers also point to ecological damage of recent coral bleaching records, like the 1998 event, which ‘killed 16% of the world’s tropical coral reefs [‘coral reeds threatened with extinction by 2050‘/’coral reefs die at pH <7.7‘] – and to some commercial fish populations that have already declined by ‘more than 90%’ – and warn specifically of ecological damage of pollutants to the polar seas [where concentrations for dissolved CO2 and toxic chemicals like PCBs are higher], far beyond our visual horizon.

Monitoring the biodiversity decline

It is not the first time scientists warn our planet’s sixth mass extinction may already be underway. It is however much easier for us to witness biodiversity declines on land – and to see for instance even plant life does not escape – than in the oceans, hidden beneath the waves, which is why another big research group has set out to establish a marine biodiversity baseline – from which to monitor further declines. [These researchers estimate the world’s oceans are home to more than one million unique species, 90 percent of which are microbial. Of the higher life forms there are probably over 20,000 different types of fish – of which 16,764 have been discovered by science. This means we may be killing fish we never even officially caught.]

© Rolf Schuttenhelm | www.bitsofscience.org

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