Ocean Warming Creates Dead Zones That Devour The Oxygen

Ocean Warming Creates Dead Zones That Devour The OxygenExtremes of heat deprive fish of the oxygen they need to survive near the ocean surface. Image: Naren Gunasekera via Flickr

Marine life faces increased threats as researchers warn that warmer waters caused by climate change could seriously reduce the levels of oxygen in the world’s seas.

Scientists in the US have identified a new hazard in a world in which the climates change and the oceans warm: measurable stretches of the seas could become sapped of oxygen.

They say that parts of the southern Indian Ocean, the eastern tropical Pacific and the Atlantic are already less oxygen-rich because of global warming. And oxygen deprivation could become increasingly widespread across large regions of ocean between 2030 and 2040.

Anyone who has ever kept a home aquarium knows that, in the summer, the fish in the tank are more likely to be seen gasping nearer the surface. That is because the colder the water, the greater its capacity for dissolved oxygen.

Chemistry change

Growing concentrations in the atmosphere of the greenhouse gas carbon dioxide have begun to change the ocean chemistry, making sea water gradually and alarmingly more acidic and less hospitable to many of the species adapted to ocean life.

Now Matthew Long, an oceanographer at the US National Centre for Atmospheric Research in Boulder, Colorado and colleagues report in Global Biogeochemical Cycles journal that they repeatedly modelled changes in the ocean’s oxygen content over the years 1920 to 2100.

“This new study tells us when we can expect the impact from climate change to overwhelm the natural variability”

Oxygen from the atmosphere gets into the sea only when it dissolves directly, or is released by photosynthesising marine plants and phytoplankton. The warmer the water, the harder life is for the creatures nearer the surface.

To make things more difficult, warmer waters are less dense, making them less likely to sink and bring the colder, more oxygen-rich waters to the surface. In unusually hot weather, “dead zones” appear in the seas, where fish and shellfish cannot survive.

The researchers warn that there will be more of these as global temperatures continue to rise. “Loss of oxygen in the ocean is one of the serious side-effects of a warming atmosphere, and a major threat to marine life,” Dr Long says.

Swiftly detectable

“Since oxygen concentrations in the ocean naturally vary, depending on variations in winds and temperature at the surface, it’s been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability.”

The new map suggests that even by 2100, some waters – off the east coasts of Africa and Australia and Southeast Asia, and parts of the South Atlantic, for instance – will remain oxygen-rich. But oxygen loss due to climate change will become detectable much more swiftly in northern waters in the Pacific, and parts of the Atlantic.

There are uncertainties. Oxygen measurements in the world’s oceans − and 70% of the planet is covered by blue water – are relatively sparse.

“We need comprehensive and sustained observations of what’s going on in the oceans to compare with what we’re learning from our models, and to understand the full impact of a changing climate,” Dr Long says.

Climate News Network

About the Author

Tim Radford, freelance journalistTim Radford is a freelance journalist. He worked for The Guardian for 32 years, becoming (among other things) letters editor, arts editor, literary editor and science editor. He won the Association of British Science Writers award for science writer of the year four times. He served on the UK committee for the International Decade for Natural Disaster Reduction. He has lectured about science and the media in dozens of British and foreign cities. 

Science that Changed the World: The untold story of the other 1960s revolutionBook by this Author:

Science that Changed the World: The untold story of the other 1960s revolution
by Tim Radford.

Click here for more info and/or to order this book on Amazon. (Kindle book)



enafarzh-CNzh-TWnltlfrdehiiditjakomsfaptruesswsvthtrurvi

LATEST VIDEOS

Blue Ocean Event : Game Over?
by Just Have a Think
A Blue Ocean Event, or Ice-Free Arctic, is the source of almost fever pitch speculation in the climate science world.…
Climate Change - The Facts by Sir David Attenborough
by David Attenborough, BBC
After one of the hottest years on record, Sir David Attenborough looks at the science of climate change and potential…
Why it’s time to think about human extinction
by Kerwin Rae
After listening to this ep with Dr David Suzuki, you’ll never be the same again. The environmentalist, activist,…
Record Temperatures 20-25C Above Norm in far North
by Paul Beckwith
The Northwest Territories of Canada had March temperatures above 20C for the first time (hit 21.6C or 71F); breaking…
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
by Chris Hawes
According to a recent major UN report, if we are to limit temperature rise to 1.5 °C and prevent the most catastrophic…
Why Climate Change Will Dull Autumn Leaf Displays
Why Climate Change Will Dull Autumn Leaf Displays
by Matthew Brookhouse
Every autumn we are treated to one of nature’s finest seasonal annual transitions: leaf colour change and fall.
Climate denial isn’t stopping climate action.
by David Wallace-Wells
Climate change denial draws headlines. But is it actually an obstacle to climate action? A great majority of Americans…
Energy Storage: How to store renewable energy?
by Total
Under your bed, in the attic even on your mobile phone, it seems there's never enough storage. It turns out it's also…

LATEST ARTICLES

Crops at risk from changing climate
Crops at risk from changing climate
by Tim Radford
Global warming could bring yet more challenges to a hungry world. New studies have identified precise ways in which a…
Seeing The Planet Break Down In Climate Crisis Is Depressing – How To Turn Your Pain Into Action
Seeing The Planet In Climate Crisis Is Depressing – Turn Your Pain Into Action
by Cameron Brick
Environmentalism can feel like a drag. People trying to reduce their environmental impact often feel stressed and…
Global Inequality Is 25% Higher Than It Would Have Been In A Climate-stable World
by Nicholas Beuret
Those least responsible for global warming will suffer the most. Poorer countries – those that have contributed far…
Jason Kenney's Victory Means We'll All Pay The Price For Fossil Fuel Emissions
Jason Kenney's Victory In Alberta Means We'll All Pay The Price For Fossil Fuel Emissions
by D.T. Cochrane
Jason Kenney has led the United Conservative Party to victory in Alberta. There were manyobjectionablecomponents to the…
How Can Trees Really Cool Our Cities Down?
How Can Trees Really Cool Our Cities Down?
by Roland Ennos, University of Hull
In cities around the world, trees are often planted to help control temperatures and mitigate the effects of the “urban…
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
by Global Warming & Climate Change
But Varshini Prakash, executive director of the Sunrise Movement, a youth-led activist group that has advocated for the…
Should The Sahara Desert Be Turned Into A Huge Solar Farm?
Should The Sahara Desert Be Turned Into A Huge Solar Farm?
by Amin Al-Habaibeh
Whenever I visit the Sahara I am struck by how sunny and hot it is and how clear the sky can be.
How Retreating From The Sea Level Rise Will Affect Our Health?
How Retreating From The Sea Level Rise Will Affect Our Health?
by Jackson Holtz
Managed retreat in the face of sea level rise will be a mixed bag, researchers predict.