Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Global Maps Detail Human-Caused Ocean Acidification

11.11.2014

Oceans Changing in Step with Rising CO2 Emissions

A team of scientists has published the most comprehensive picture yet of how acidity levels vary across the world’s oceans, providing a benchmark for years to come as enormous amounts of human-caused carbon emissions continue to wind up at sea.


In northern winter, the Bering Sea, dividing Alaska and Siberia, becomes the most acidic region on earth (in purple) as shown in this February 2005 acidity map in pH scale. Temperate oceans are less acidic. The equatorial Pacific is left blank due to its high variability around El Niño and La Niña events. (Takahashi)


The saturation state of the mineral aragonite, essential to shell-builders, tends to fall as waters become more acidic. The South Pacific Ocean is heavily oversaturated with respect to aragonite (in red) while the polar oceans (in blue) are less saturated, as shown in this February 2005 map. The pink lines represent approximate polar sea ice edges. (Takahashi)

“We have established a global standard for future changes to be measured,” said Taro Takahashi, a geochemist at Columbia’s Lamont-Doherty Earth Observatory who published the maps with his colleagues in the August issue of the journal Marine Chemistry.

The maps provide a monthly look at how ocean acidity rises and falls by season and geographic location, along with saturation levels of calcium carbonate minerals used by shell-building organisms. The maps use 2005 as a reference year and draw on four decades of measurements by Lamont-Doherty scientists and others.

The oceans have taken up a quarter of the carbon dioxide humans have put in the atmosphere over the last two hundred years. But their help in offsetting global warming has come at a price: the oceans are growing more acidic as they absorb our excess CO2.

To what extent ocean acidification may harm marine life and ecosystems is still unclear, but already signs of stress have appeared in corals, mollusks and other shell-builders living in regions with naturally more acidic water. Since the industrial era began, average surface seawater pH in temperate oceans has fallen from 8.2 to 8.1 by 0.1 pH unit, equal to a 30 percent increase in acid concentration. (A lower pH indicates more acidic conditions.)

The saturation state of the mineral aragonite, essential to shell-builders, tends to fall as waters become more acidic. The South Pacific Ocean is heavily oversaturated with respect to aragonite (in red) while the polar oceans (in blue) are less saturated, as shown in this February 2005 map. The pink lines represent approximate polar sea ice edges. (Takahashi)

Taro Takahashi has spent more than four decades measuring the changing chemistry of the world’s oceans. Here, aboard the R/V Melville, he celebrates after sampling waters near the bottom of the Japan Trench in 1973. (Lamont-Doherty archives)

The vast tropical and temperate oceans, where most coral reefs grow, see the least variation, with pH hovering between 8.05 and 8.15 as temperatures fluctuate in winter and summer. Here, the waters are oversaturated with respect to the mineral aragonite—a substance that shell-building organisms need to thrive.

Ocean pH fluctuates most in the colder waters off Siberia and Alaska, the Pacific Northwest and Antarctica. In spring and summer, massive plankton blooms absorb carbon dioxide in the water, raising pH and causing seawater acidity to fall. In winter, the upwelling of CO2-rich water from the deep ocean causes surface waters to become more acidic. Acidification of the Arctic Ocean in winter causes aragonite levels to fall, slowing the growth of pteropods, planktic snails that feed many predator fish.

The maps reveal that the northern Indian Ocean is at least 10 percent more acidic than the Atlantic and Pacific oceans, which could be due to its unique geography. Cut off from the Arctic Ocean, the chemistry of the northern Indian Ocean is influenced by rivers draining the massive Eurasian continent as well as seasonal monsoon rains.

By analyzing long-term data collected off Iceland, Bermuda, the Canary Islands, Hawaii and the Drake Passage, off the southern tip of South America, Takahashi finds that waters as far north as Iceland and as far south as Antarctica are acidifying at the rate of 5 percent per decade. His estimate corresponds to the amount of CO2 humans are adding to the atmosphere, and is consistent with several recent estimates, including a 2014 study in the journal Oceanography led by Nicholas Bates, research director at the Bermuda Institute of Ocean Sciences.

“This is exactly what we’d expect based on how much CO2 we’ve been putting in the air,” said Rik Wanninkhof, a Miami-based oceanographer with the National Oceanic and Atmospheric Administration (NOAA) who was not involved in the study. “This is an important point for scientists to underscore—these calculations are not magic.”

If the current pace of ocean acidification continues, warm-water corals by 2050 could be living in waters 25 percent more acidic than they are today, said Takahashi. While corals can currently tolerate shifts that big, marine biologists wonder if they can sustain growth at lower pH levels year-round. “In the long run it is the average pH that corals see that matters to their ability to grow and build a coral reef,” said Chris Langdon, a marine biologist at the University of Miami, who was not involved in the study.

Ocean acidification is already having an impact, especially in places where the seasonal upwelling of deep water has made seawater naturally more acidic. In a recent study by researchers at NOAA, more than half of the pteropods sampled off the coast of Washington, Oregon and California showed badly dissolved shells.

Ocean acidification has been linked to fish losing their ability to sniff out predators, and the die-off of baby oysters in hatcheries off Washington and Oregon, where more acidic deep water comes to the surface each spring and summer.

By 2100, ocean acidification could cost the global economy $3 trillion a year in lost revenue from fishing, tourism and intangible ecosystem services, according to a recent United Nations report. The U.S. Government Accountability Office, the watchdog arm of Congress, has reached similar findings and recommended that President Obama create a research and monitoring program dedicated to ocean acidification.

Other authors of the study: Stuart Sutherland, David Chipman (now retired), John Goddard and Cheng Ho, all of Lamont-Doherty; and Timothy Newberger, Colm Sweeney and David Munro, all of University of Colorado, Boulder.


Media Inquiries:
Kim Martineau
kmartine@ldeo.columbia.edu
Office:(845) 365-8708
Cell: (646)-717-0134

Kim Martineau | EurekAlert!
Further information:
http://www.ldeo.columbia.edu/news-events/new-global-maps-detail-human-caused-ocean-acidification

More articles from Earth Sciences:

nachricht Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

nachricht Modeling magma to find copper
13.01.2017 | Université de Genève

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>