Archive for March, 2007

Corals more resilient to climate change than earlier believed

Reef-building corals may be more resilient against climate change than previously thought and 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, a new study by an Israeli zoologist has revealed., 30 March 2007. Article.

Overloaded oceans

Ocean acidification is a real and potentially devastating consequence of climate change that demands immediate attention.

An excess of fossil fuel-derived carbon dioxide is causing profound changes in ocean chemistry. These changes are some of the most pressing problems presented by the burning of fossil fuels, but they get little attention.

A small but growing number of scientists are turning their thoughts to the oceans and their findings demand that we take action.

Tony Haymet, ninemsn, 30 March 2007. Article.

Some corals may survive acidification caused by rising CO2

Several studies have shown that increased atmospheric carbon dioxide levels are acidifying the world’s oceans. This is significant for coral reefs because acidification strips carbonate ions from seawater, making it more difficult for corals to build the calcium carbonate skeletons that serve as their structural basis. Research has shown that many species of coral, as well as other marine microorganisms, fare quite poorly under the increasingly acidic conditions forecast by some models. However, the news may not be bad for all types of corals. A study published in the March 30 issue of the journal Science, suggests that some corals may weather acidification better than others.

Israeli biologists Maoz Fine and Dan Tchernov found that some stony corals can survive increased acidity by morphing into soft-bodied polyp forms. The corals produce hard skeletons again once pH level returns to normal., 29 March 2007. Article.

Scleractinian Coral Species Survive and Recover from Decalcification

Anthropogenic-driven accumulation of carbon dioxide in the atmosphere and projected ocean acidification have raised concerns regarding the eventual impact on coral reefs. This study demonstrates that skeleton-producing corals grown in acidified experimental conditions are able to sustain basic life functions, including reproductive ability, in a sea anemone-like form and will resume skeleton building when reintroduced to normal modern marine conditions. These results support the existence of physiological refugia, allowing corals to alternate between nonfossilizing soft-body ecophenotypes and fossilizing skeletal forms in response to changes in ocean chemistry. This refugia, however, does not undermine the threats to reef ecosystems in a high carbon dioxide world.

Fine M. & Tchernov D., 2007. Scleractinian coral species survive and recover from decalcification. Science 315: 1811. 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.

Michael Armstrong, Homer News, 28 March 2007. Article.

Whatever The Warming, Ocean Acidifies From Carbon-dioxide Buildup

A new study indicates that future changes in ocean acidification caused by atmospheric carbon dioxide emissions are largely independent of the amount of climate change caused by those emissions.

ScienceDaily, 27 March 2007. Article.

Climate change feedbacks on future oceanic acidification

Oceanic anthropogenic CO2 uptake will decrease both the pH and the aragonite saturation state (Ωarag) of seawater leading to an oceanic acidification. However, the factors controlling future changes in pH and Ωarag are independent and will respond differently to oceanic climate change feedbacks such as ocean warming, circulation and biological changes. We examine the sensitivity of these two CO2-related parameters to climate change feedbacks within a coupled atmosphere-ocean model. The ocean warming feedback was found to dominate the climate change responses in the surface ocean. Although surface pH is projected to decrease relatively uniformly by about 0.3 by the year 2100, we find pH to be insensitive to climate change feedbacks, whereas Ωarag is buffered by ~15%. Ocean carbonate chemistry creates a situation whereby the direct pH changes due to ocean warming are almost cancelled by the pH changes associated with dissolved inorganic carbon concentrations changes via a reduction in CO2 solubility from ocean warming. We show that the small climate change feedback on future surface ocean pH is independent to the amount of ocean warming. Our analysis therefore implies that future projections of surface ocean acidification only need to consider future atmospheric CO2 levels, not climate change induced modifications in the ocean.

McNeil BI & Matear, RJ, 2007. Climate change feedbacks on future oceanic acidification. Tellus B 59:2 191-198. Article.

Time to address threat of ocean acidification’s impact on key members of ecosystem

Scientists’ warnings about global climate change have been a hard sell in some quarters over the years because the consequences unfold over the course of decades, too slow to even seem tangible. For every ice sheet chunk that falls into the ocean, there’s one weekend of really heavy snow to restore complacency.

Sandiegosource, 22 March 2007. Article. (subscription required)

Study: Oceans acidify from CO2 buildup

A U.S. study suggests ocean acidification changes from CO2 emissions are mostly independent of any temperature increase caused by the emissions.

The ocean plays a major role in the uptake of carbon dioxide emitted from fossil-fuel burning, helping to moderate future climate change. However, the addition of the gas to the ocean alters marine chemistry by increasing acidity, posing a threat to shelled organisms and their predators.

Long Cao of the University of Illinois and colleagues sought to quantify the effect of climate change on ocean acidity and on the calcium-carbonate minerals.

m&c, 22 March 2007. Article.

Global warming ‘threatening’ shellfish

MUSSELS, among other shellfish species, are reportedly in danger of being wiped out by increasing greenhouse gas levels in seawater.

Certain types of shellfish are being threatened by the rise of global warming, European scientists have discovered.
Most shellfish are at some risk, but the worst affected species are oysters and mussels, which are in serious danger of being wiped out because of the increase in greenhouse gas levels in seawater, according to the scientists.

The report, which was carried out by French and Dutch scientists at France’s CNRS research centre and the Netherlands Institute of Ecology has found that rising levels of acid in the sea caused by carbon dioxide emissions are threatening some of the world’s most popular edible shellfish. Scientists said the carbon dioxide (Co2) was preventing oysters and mussels from producing shells, making them slow to develop and vulnerable to predators.
The report also found that the creatures’ shells were reduced by up to 25% in seawater, with Co2 levels predicted for the end of this century. Increasing Co2 levels in the water led to the shells dissolving completely. It is estimated that 25-million tonnes of Co2 are absorbed by the sea.

Fishfarmer Magazine, 21 March 2007. Article.

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Ocean acidification in the IPCC AR5 WG II

OUP book