Archive for April, 2007

Sea life at risk as acid levels rise in oceans

Carbon dioxide released by fossil fuel combustion has increased acidity levels of the ocean by 30 percent, and in the decades ahead will create new risks for coral, zooplankton and other creatures that help support North Pacific fisheries, according to researchers who gathered Monday at the University of Washington.

In a two-day workshop that ends today, these scientists are reviewing what is known about this grim corner of climate change and brainstorming ways to measure and assess the threats to a marine ecosystem that yields North America’s largest seafood harvests.

Hal Bernton, Seattle Times Newspaper, 24 April 2007. Article.

Globally increased pelagic carbonate production during the Mid-Brunhes dissolution interval and the CO2 paradox of MIS 11

The Mid-Brunhes dissolution interval (MBDI) represents a period of global carbonate dissolution, lasting several hundred thousand years, centred around Marine Isotope Stage (MIS) 11. Here we report the effects of dissolution in ODP core 982, taken from 1134 m in the North Atlantic. Paradoxically, records of atmospheric CO2 from Antarctic ice-cores reveal no long term trend over the last 400 kyr and suggest that CO2 during MIS 11 was no higher than during the present interglacial. We suggest that a global increase in pelagic carbonate production during this period, possibly related to the proliferation of the Gephyrocapsa coccolithophore, could have altered marine carbonate chemistry in such a way as to drive increased dissolution under the constraints of steady state. An increase in the production of carbonate in surface waters would cause a drawdown of global carbonate saturation and increase dissolution at the seafloor. In order to reconcile the record of atmospheric CO2 variability we suggest that an increase in the flux of organic matter from the surface to deep ocean, associated with either a net increase in primary production or the enhanced ballasting effect provided by an increased flux of CaCO3, could have countered the effect of increased calcification on CO2.

Barker et al., 2006. Globally increased pelagic carbonate production during the Mid-Brunhes dissolution interval and the CO2 paradox of MIS 11. Quaternary Science Reviews 25: 3278-3293. Article.

NOAA Seeks Guidance on Ocean Acidification Research

As the concentration of carbon dioxide in the atmosphere increases, the oceans become more acidic. The U.S. National Oceanic and Atmospheric Administration (NOAA) has already developed a 5- year interdisciplinary program on ocean acidification, which includes establishing coral reef monitoring stations, research on the physiological responses of various organisms to increasing ocean acidity, modeling of ocean acidification and its socioeconomic effect, and development of technology for measuring and monitoring carbon dioxide in the oceans.

NOAA’s Science Advisory Board (SAB) is considering whether the agency’s plans are appropriate for addressing the requirements of both science and national policy and whether NOAA should be the lead agency in this area of research.

At the SAB’s 6 March meeting, Richard Feely, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory, updated Board members on the current state of knowledge on ocean acidification. “Ocean acidification is one of the most serious threats to the world’s ocean ecosystems aris- ing from carbon dioxide emissions,” he said.

Under current carbon dioxide scenarios, by the end of the century the world’s oceans could be unable to maintain current rates of calcification, according to Feely. Populations of many species at the bottom of the food chain that rely on calcification, such as coccolithophores, foraminifera, and pteropods, could be devastated by these changes to ocean acidity. In that fish larvae are very sensitive to changes in carbon dioxide in the ocean, Feely said. Changes in the food chain or larvae survival rates could affect fisheries, such as the Pacific salmon fishery.

Congress requested, in its 2006 renewal of the Magnuson Stevens Fishery Conservation and Management Act, that the U.S. National Research Council (NRC) conduct a study on ocean acidification and how this process affects the United States. However, before the study can begin, NOAA needs to develop a statement of task describing what it would like the committee to focus on and needs to find funds for the study.

John Snow, dean of the College of Atmospheric and Geographic Sciences at the University of Oklahoma, Norman, said that there are several areas where the SAB could provide advice to NOAA about its involvement in ocean acidification research, such as helping to design the statement of task for the NRC committee. In addition, Snow, an SAB member, said the Board could recommend that NOAA develop an observing system for ocean acidification and that NOAA work with other U.S. agencies or international partners in this research.

Eos, 88(11):133, 13 March 2007. Journal web site.

Ocean experts urge faster action on marine reserves

The Earth’s oceans are being destroyed at a much faster rate than they are being protected, said the world’s leading marine experts at the end of the IUCN Marine Protected Area Summit.

To make oceans more resistant to the impacts of climate change, other stress factors such as pollution and overfishing need to be kept away from marine ecosystems such as coral reefs, a major source of income and protein for millions of people worldwide.

“Climate change makes oceans warmer and more acidic, which causes corals to bleach and erodes their ability to build reef skeletons. But corals can adapt and survive if they are healthy and don’t suffer from sedimentation or disruptive fishing practices,” said Carl Gustaf Lundin, Head of IUCN’s Marine Programme.

Better management of marine environments will also save mankind from accelerated climate change. Today, oceans are the world’s largest carbon sink, absorbing around 50 per cent of atmospheric CO² every year. However, continued discharges of carbon dioxide and poor marine management may turn oceans from a carbon sink into a major carbon source, releasing vast stores of carbon into the atmosphere, thus exacerbating climate change., 6 April 2007. Article.

Carbon emissions causing ocean acidification

An acidic ocean that disintegrates microscopic sea life might sound like “The Horror from the Deep,” the plot of a bad 1950s science fiction movie. It’s a scenario with chilling effects, including the destruction of pteropods, the zooplankton which feed salmon, cod, herring, mackerel and baleen whales.

Along with rising sea levels, warmer temperatures and shrinking glaciers, ocean acidification is another effect of increased carbon dioxide in the earth’s atmosphere. Only recently have scientists begun to study the change in ocean chemistry caused by human-caused carbon emissions.

“This is a very young field,” said Dr. Jeff Short, an environmental chemist and adviser to the Alaska Marine Conservation Council. “It has only been widely appreciated in the last five years.”, Michael Armstrong, 28 March 2007. Article.

California Adopts First Phase of Ocean Preserves

California wildlife regulators adopted a sweeping ocean protection plan on Friday, the first such statewide effort in the country, intended to establish a network of underwater refuges.

The plan, unanimously approved by members of the California Fish and Game Commission, will create a statewide system of connected ocean preserves where fishing and other human activities would be limited or banned.

The first phase sets aside the waters along a 200-mile stretch of the coast, including tidal areas that fan out three miles from shore, to protect marine habitat between Point Conception, near Santa Barbara, and Half Moon Bay, about 25 miles south of here.

Environmental advocates hailed the vote, with the Natural Resources Defense Council calling the approved plan a “balanced compromise using high quality science.” But commercial fishermen say the plan does little more than further restrict their industry.

“Just protecting part of the ocean won’t work,” said Zeke Grader, executive director of the Pacific Coast Federation of Fishermen’s Associations. “We can’t just restrict fishermen. We need to address pollution and acidification of the oceans.”

The New York Times, 14 APril 2007. Article.

World Heritage List Sites At Serious Risk From Climate Change

Some of the world’s most renowned natural and cultural sites, from the Great Barrier Reef to Kilimanjaro National Park to the city of Venice, are at serious threat from climate change, according to a report released by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Rising sea levels, melting glaciers, increased risks of flooding and reduced marine and land biodiversity could all have potentially disastrous effects on the 830 sites inscribed on the UNESCO World Heritage List, the report said.

UNESCO Director-General Koïchiro Matsuura called for “an integrated approach to issues of environmental preservation and sustainable development,” warning that climate change will constitute an enormous challenge over the next century.

The report, which featured 26 case studies, focused on five areas: glaciers, marine biodiversity, terrestrial biodiversity, archaeological sites, and historic cities and settlements.

One of the at-risk sites is the Great Barrier Reef, off the north-eastern coast of Australia. The report found that rising sea temperatures and increasing oceanic acidification mean that corals are more and more likely to bleach and turn white, jeopardizing the numerous fish species which rely on the reef.
Europaworld, 15 April 2007. Web site.

B/Ca in planktonic foraminifera as a proxy for surface seawater pH

Boron isotope systematics indicate that boron incorporation into foraminiferal CaCO3 is determined by the partition coefficient, KD (= inline equation), and [B(OH)4 −/HCO3 −]seawater, providing, in principle, a method to estimate seawater pH and PCO2. We have measured B/Ca ratios in Globigerina bulloides and Globorotalia inflata for a series of core tops from the North Atlantic and the Southern Ocean and in Globigerinoides ruber (white) from Ocean Drilling Program (ODP) site 668B on the Sierra Leone Rise in the eastern equatorial Atlantic. B/Ca ratios in these species of planktonic foraminifera seem unaffected by dissolution on the seafloor. KD shows a strong species-specific dependence on calcification temperature, which can be corrected for using the Mg/Ca temperature proxy. A preliminary study of G. inflata from Southern Ocean sediment core CHAT 16K suggests that temperature-corrected B/Ca was 30% higher during the last glacial. Correspondingly, pH was 0.15 units higher and aqueous PCO2 was 95 μatm lower at this site at the Last Glacial Maximum. The covariation between reconstructed PCO2 and the atmospheric pCO2 from the Vostok ice core demonstrates the feasibility of using B/Ca in planktonic foraminifera for reconstructing past variations in pH and PCO2.

Yu, J., H. Elderfield, and B. Hönisch (2007), B/Ca in planktonic foraminifera as a proxy for surface seawater pH. Paleoceanography 22, PA2202, doi:10.1029/2006PA001347. Abstract.

Marine life at peril as CO2 rises

Rising carbon dioxide emissions are making the world’s oceans more acidic, particularly closer to the poles, heralding disaster for marine life.

The warning comes in a major UN report on climate change impact., 7 April 2007. Article

Corals can survive acidic waters

Mediterranean corals could strip, but not die, in response to climate change.

Reef-building corals may be more resilient against climate change than scientists had previously thought. Researchers have discovered that some species are able to survive an increase in seawater acidity, even though it strips the individual coral polyps of their protective calcium carbonate skeletons. This may be good news for individual polyps, but it doesn’t change the gloomy outlook for reef ecosystems.

As atmospheric carbon dioxide levels continue to rise, so do the levels of dissolved carbon dioxide in sea water. This leads to an increase in ocean-borne carbonic acid, which is capable of dissolving calcium carbonate. “This is a major problem for corals,” says Maoz Fine, a marine zoologist at Bar-Ilan University in Israel. “Essentially, acidification leads to naked coral.”

Fairless D., Nature News, 29 March 2007, Article

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Ocean acidification in the IPCC AR5 WG II

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