Scientists warn of 'deadly trio' risk to ailing oceans

Oct 03, 2013 by Mariette Le Roux
Buildings are seen near the ocean as on March 14, 2012 in North Miami, Florida.

Marine scientists warned Thursday that our oceans are declining more rapidly than previously thought—becoming ever warmer and more acidic and losing oxygen at an alarming rate.

"We have been taking the for granted," states a report that warns of a "deadly trio" of , acidification, and loss.

"We are... exposing organisms to intolerable evolutionary pressure," it said. "The next mass (species) extinction event may have already begun."

The scientific review by the International Programme on the State of the Ocean (IPSO) and the International Union for the Conservation of Nature cautioned of unprecedented ocean acidification as humans keep burning oil and coal and pump out carbon dioxide (CO2)—about a third of which is absorbed by the sea.

Today's rate of carbon release, about 30 gigatonnes of CO2 per year, was at least 10 times faster than that which preceded the last major species extinction on Earth about 55 million years ago, it said.

The level of is unparallelled in at least 300 million years, said the review released just a week after the UN's Intergovernmental Panel on Climate Change said the ocean was absorbing more than 90 percent of the heat trapped on Earth by greenhouse gas emissions.

The new report said the average upper ocean temperature has increased by 0.6 degrees Celsius (1.08 deg Fahrenheit) over the last 100 years. Further warming will likely cause the disappearance of Arctic summer sea ice, further oxygen depletion and the release of Earth-warming methane trapped in the Arctic seabed.

It also warned of a fast drop in dissolved oxygen in seawater—with predictions of a 1-7 percent decline by 2100 caused by the effects of and nutrient runoff into the sea from agricultural fertilisers and sewage.

"It is the simultaneous occurence of the 'deadly trio' of , warming and deoxygenation that is seriously affecting how productive and efficient the ocean is," said a summary of the reports that make up the review.

"Many organisms will find themselves in unsuitable environments" as the water consistency changes, the number of oxygen-poor "dead zones" increase and coral reefs die off.

This is all happening in marine ecosystems already damaged by human activities like overfishing and pollution, said the document.

Its authors propose urgent interventions: reducing Earth-warming to make sure we contain the global temperature rise to 2.0 C (3.6 F) over pre-Industrial Revolution levels—a UN target that seems ever more out of reach.

They also called for the elimination of harmful fishing subsidies that drive overexploitation, and banning destructive fishing practices like bottom-trawling that indiscriminately damage the ocean floor and the creatures that live there.

The ocean covers nearly three quarters of the Earth's surface, provides about half of the oxygen we breathe and feeds billions of people every year.

"The health of the ocean is spiralling downwards far more rapidly than we had thought," IPSO scientific director Alex Rogers said of the review.

"We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated. The situation should be of the gravest concern to everyone since everyone will be affected by changes in the ability of the ocean to support life on Earth."

Explore further: Ocean acidification amplifies global warming (Update)

add to favorites email to friend print save as pdf

Related Stories

Ocean acidification amplifies global warming (Update)

Aug 25, 2013

Scientists at the Max Planck Institute for Meteorology (MPI-M), Dr. Katharina Six, Dr. Silvia Kloster, Dr. Tatiana Ilyina, the late Dr. Ernst Maier-Reimer and two co-authors from the US, demonstrate that ...

Speed of ocean acidification concerns scientists

Sep 27, 2012

Speaking at the Third International Symposium on the Ocean in a High-CO2 World this week in Monterey, California, Dr Daniela Schmidt, a geologist from the University of Bristol, warned that current rates ...

Past decade saw unprecedented warming in the deep ocean

Jul 02, 2013

From 1975 on, the global surface ocean has shown a pronounced-though wavering-warming trend. Starting in 2004, however, that warming seemed to stall. Researchers measuring the Earth's total energy budget-the balance of sunlight ...

Peering through the global carbon cycle

Aug 21, 2013

The oceans are one of the sink absorbing carbon dioxide derived from human activity. Yet fully quantifying the ocean's carbon uptake under a changing climate remains challenging.

Recommended for you

'Shocking' underground water loss in US drought

2 hours ago

A major drought across the western United States has sapped underground water resources, posing a greater threat to the water supply than previously understood, scientists said Thursday.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Howhot
5 / 5 (4) Oct 09, 2013
Our oceans are becoming warmer and more acidic and losing oxygen at an alarming rate! We all agree. All in favor; aye. no Nays, the motion caries.