Archive for November, 2008

Oceans Ten Times More Acidic Than Thought

Increasing levels of carbon dioxide in the atmosphere may make Earth’s oceans more acidic faster than previously thought—unbalancing ecosystems in the process, a new study says.

Since 2000, scientists have measured the acidity of seawater around Tatoosh Island off the coast of Washington state. The acidity increased ten times quicker than climate models predicted.

The research also revealed the corrosive effect of acidic oceans could trigger a dramatic shift in coastal species and jeopardize shellfish stocks.

“The increase in acidity we saw during our study was about the same magnitude as we expect over the course of the next century,” said study co-author Timothy Wootton, a marine biologist from the University of Chicago.
Continue reading ‘Oceans Ten Times More Acidic Than Thought’

Acidic seas threaten coral and mussels

Impact of rising carbon dioxide levels far worse than previously thought

Rising carbon dioxide levels are increasing acidity in the oceans 10 times faster than scientists thought, posing a greater threat to shell-forming creatures such as coral and mussels.

An eight-year project in the Pacific has found that rising marine acid levels will challenge many organisms, because their shell-making chemistry is critically dependent on a less acidic, more alkaline environment. The study monitored seawater pH levels at the north-east Pacific island of Tatoosh off Washington state in the United States.
Continue reading ‘Acidic seas threaten coral and mussels’

Marine life faces ‘acid threat’

Man-made pollution is raising ocean acidity at least 10 times faster than previously thought, a study says.

Researchers say carbon dioxide levels are having a marked effect on the health of shellfish such as mussels.

They sampled coastal waters off the north-west Pacific coast of the US every half-hour for eight years.

The results, published in the journal PNAS, suggest that earlier climate change models may have underestimated the rate of ocean acidification.
Continue reading ‘Marine life faces ‘acid threat’’

Ocean turning to acid at lightning speed

Increased carbon dioxide (CO2) in the atmosphere is making the Pacific coast acidic far more rapidly than previously believed, potentially wreaking havoc for creatures living in it that are unable to tolerate the swiftly changing environment.

Ecologists at the University of Chicago tracked the acidity of the Pacific off an island close to Washington state over the course of eight years. Their results, published today in Proceedings of the National Academy of Sciences: the waters here are becoming acidic 10 times more quickly than had been predicted using other models. Their data also shows that populations of mussels—key animals in that ecosystem—are declining rapidly as the ocean becomes less alkaline.
Continue reading ‘Ocean turning to acid at lightning speed’

Unexpected rise in carbon-fuelled ocean acidity threatens shellfish, say scientists

The world’s oceans are becoming acidic more quickly than climate change models predict, according to scientists who claim it will have a dramatic impact on marine ecosystems.

Water samples collected around an island in the eastern Pacific over the past eight years showed seawater had acidified more than 20 times faster than scientists expected. The effect could be devastating for shellfish and other crustaceans, because acidic waters dissolve calcium carbonate used by the organisms to make their protective shells.
Continue reading ‘Unexpected rise in carbon-fuelled ocean acidity threatens shellfish, say scientists’

Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year dataset

Increasing global concentrations of atmospheric CO2 are predicted to decrease ocean pH, with potentially severe impacts on marine food webs, but empirical data documenting ocean pH over time are limited. In a high-resolution dataset spanning 8 years, pH at a north-temperate coastal site declined with increasing atmospheric CO2 levels and varied substantially in response to biological processes and physical conditions that fluctuate over multiple time scales. Applying a method to link environmental change to species dynamics via multispecies Markov chain models reveals strong links between in situ benthic species dynamics and variation in ocean pH, with calcareous species generally performing more poorly than noncalcareous species in years with low pH. The models project the long-term consequences of these dynamic changes, which predict substantial shifts in the species dominating the habitat as a consequence of both direct effects of reduced calcification and indirect effects arising from the web of species interactions. Our results indicate that pH decline is proceeding at a more rapid rate than previously predicted in some areas, and that this decline has ecological consequences for near shore benthic ecosystems.
Continue reading ‘Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year dataset’

Procedures for measurement of carbonate ion concentrations in seawater by direct spectrophotometric observations of Pb(II) complexation

The health of coral reefs and calcareous plankton is strongly influenced by the carbonate saturation state of seawater. Calculations of carbonate saturation states currently require measurements of two CO2 system parameters, such as pH and total dissolved carbon, plus thermodynamic calculations that relate carbonate ion concentrations to directly measured parameters. In this work we report novel procedures for direct measurements of carbonate ion concentrations and saturation states in seawater. Measurements are obtained via ultraviolet spectroscopic observations of Pb(II) spectra as the relative concentrations of PbCO30 and an ensemble of lead chloride complexes vary in response to dissolved CO32−. Measurement precision is enhanced by parameterization in terms of absorbance ratios. The PbCO30 stability constant, and Pb(II) molar absorbance ratios in seawater, were determined at 25 °C over a range of salinity between 36 and 20. The procedures described in this work are well suited to measurements throughout the normal range of carbonate ion concentrations in the oceans. Rapid equilibration rates for Pb(II) carbonate complexation make the procedures described in this work well suited to rapid direct analysis in situ.
Continue reading ‘Procedures for measurement of carbonate ion concentrations in seawater by direct spectrophotometric observations of Pb(II) complexation’

Acid Test: Are the Oceans Already Lost?

Continue reading ‘Acid Test: Are the Oceans Already Lost?’

The Ocean Becomes More Acidic by Human-induced CO2 Emissions

Researchers in Australia have discovered that the tipping point for ocean acidification caused by human-induced CO2 emissions is much closer than first thought, with estimates suggesting that the Southern Ocean could become too acidic by 2030.

According to a report by ABC News, scientists from the University of New South Wales (UNSW) and CSIRO looked at seasonal changes in pH and the concentration of an important chemical compound, carbonate, in the Southern Ocean.

The results show that these seasonal changes will actually amplify the effects of human carbon dioxide emissions on ocean acidity, speeding up the process of ocean acidification by 30 years.

The ocean is an enormous sink for CO2, but unfortunately this comes at a cost, according to Dr Ben McNeil, senior research fellow at the UNSW’s Climate Change Research Centre.

“The ocean is a fantastic sponge for CO2, but as it dissolves in the ocean it reduces the pH of the ocean, so the ocean becomes more acidic,” said Dr McNeil.
Continue reading ‘The Ocean Becomes More Acidic by Human-induced CO2 Emissions’

Ocean growing more acidic faster than once thought

Increasing acidity threatens sea life

University of Chicago scientists have documented that the ocean is growing more acidic faster than previously thought. In addition, they have found that the increasing acidity correlates with increasing levels of atmospheric carbon dioxide, according to a paper published online by the Proceedings of the National Academy of Sciences on Nov. 24.

“Of the variables the study examined that are linked to changes in ocean acidity, only atmospheric carbon dioxide exhibited a corresponding steady change,” said J. Timothy Wootton, the lead author of the study and Professor of Ecology and Evolution at the University of Chicago.

The increasingly acidic water harms certain sea animals and could reduce the ocean’s ability to absorb carbon dioxide, the authors said. Scientists have long predicted that higher levels of atmospheric carbon dioxide would make the ocean more acidic. Nevertheless, empirical evidence of growing acidity has been limited.

The new study is based on 24,519 measurements of ocean pH spanning eight years, which represents the first detailed dataset on variations of coastal pH at a temperate latitude—where the world’s most productive fisheries live.

“The acidity increased more than 10 times faster than had been predicted by climate change models and other studies,” Wootton said. “This increase will have a severe impact on marine food webs and suggests that ocean acidification may be a more urgent issue than previously thought, at least in some areas of the ocean.”
Continue reading ‘Ocean growing more acidic faster than once thought’

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Ocean acidification in the IPCC AR5 WG II

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