Southern Ocean carbon sink weakens
Scientists have observed the first evidence that the Southern Ocean’s ability to absorb carbon dioxide, the major greenhouse gas, has weakened by about 15 per cent per decade since 1981. The Southern Ocean normally cycles about 15% of the world's carbon dioxide, but can no longer keep up. Researchers had predicted this weakening would occur somewhere in the second half of this century, not this soon. The Southern Ocean's efficiency at cycling vast amounts of carbon dioxide is due to its cool waters.
Now a four-year study by scientists from Germany's Max-Planck Institute for Biogeochemistry, the University of East Anglia (UEA) and the British Antarctic Survey (BAS) reveals that an increase in winds over the Southern Ocean, caused by greenhouse gases and ozone depletion, has led to a release of stored CO2 into the atmosphere and is now preventing further absorption of the greenhouse gas.
The study [*abstract] published in Science today shows that this weakening of one of the Earth’s major carbon dioxide sinks will lead to higher levels of atmospheric carbon dioxide in the long-term, in what is called a 'positive feedback'.
The Biopact thinks these findings once again strengthen the case of those who say we may already be facing a 'dangerous climate change' scenario that warrants radical interventions and the uncompromising implementation of the precautionary principle. Likewise, the case for the massive introduction of carbon negative bioenergy systems ('BECS') that take historic CO2 emissions out of the atmosphere is becoming ever stronger:
biofuels :: energy :: sustainability :: climate change :: carbon dioxide :: carbon sink :: Southern Ocean :: abrupt climate change :: Bio-energy with Carbon Storage :: carbon negative :: biomass :: bioenergy ::
Professor Chris Rapley, Director of British Antarctic Survey makes the point on the need to limit our reliance on fossil fuels: "Since the beginning of the industrial revolution the world's oceans have absorbed about a quarter of the 500 gigatons of carbon emitted into the atmosphere by humans. The possibility that in a warmer world the Southern Ocean - the strongest ocean sink - is weakening is a cause for concern."
The saturation of the Southern Ocean was revealed by scrutinising observations of atmospheric CO2 from 40 stations around the world. Since 1981 the Southern Ocean sink ceased to increase, whereas CO2 emissions increased by 40%.
Dr Paul Fraser, who leads research into atmospheric greenhouse gases at Australia's CSIRO Marine and Atmospheric Research, says the international team’s four-year study concludes that the weakening is due to human activities.
“The researchers found that the Southern Ocean is becoming less efficient at absorbing carbon dioxide due to an increase in wind strength over the Ocean, resulting from human-induced climate change,” Dr Fraser says.
“The increase in wind strength is due to a combination of higher levels of greenhouse gases in the atmosphere and long-term ozone depletion in the stratosphere, which previous CSIRO research has shown intensifies storms over the Southern Ocean.”
The increased winds influence the processes of mixing and upwelling in the ocean, which in turn cause an increased release of carbon dioxide into the atmosphere, reducing the net absorption of carbon dioxide into the ocean.
More information:
Corinne Le Quéré, et al., Saturation of the Southern Ocean CO2 Sink Due to Recent Climate Change, Science, Published Online May 17, 2007, Science DOI: 10.1126/science.1136188
Eurekalert: Climate change affects Southern Ocean carbon sink - May 18, 2007.
CSIRO: Southern ocean carbon sink weakened - May 18, 2007.
Article continues
Now a four-year study by scientists from Germany's Max-Planck Institute for Biogeochemistry, the University of East Anglia (UEA) and the British Antarctic Survey (BAS) reveals that an increase in winds over the Southern Ocean, caused by greenhouse gases and ozone depletion, has led to a release of stored CO2 into the atmosphere and is now preventing further absorption of the greenhouse gas.
The study [*abstract] published in Science today shows that this weakening of one of the Earth’s major carbon dioxide sinks will lead to higher levels of atmospheric carbon dioxide in the long-term, in what is called a 'positive feedback'.
"This is the first time that we've been able to say that climate change itself is responsible for the saturation of the Southern Ocean sink. This is serious. All climate models predict that this kind of 'feedback' will continue and intensify during this century. The Earth's carbon sinks - of which the Southern Ocean accounts for 15% � absorb about half of all human carbon emissions. With the Southern Ocean reaching its saturation point more CO2 will stay in our atmosphere." - Lead author Dr Corinne Le Quéré, UEA and BAS.The new research suggests that stabilisation of atmospheric CO2 is even more difficult to achieve than previously thought. Additionally, acidification in the Southern Ocean is likely to reach dangerous levels earlier than the projected date of 2050.
The Biopact thinks these findings once again strengthen the case of those who say we may already be facing a 'dangerous climate change' scenario that warrants radical interventions and the uncompromising implementation of the precautionary principle. Likewise, the case for the massive introduction of carbon negative bioenergy systems ('BECS') that take historic CO2 emissions out of the atmosphere is becoming ever stronger:
biofuels :: energy :: sustainability :: climate change :: carbon dioxide :: carbon sink :: Southern Ocean :: abrupt climate change :: Bio-energy with Carbon Storage :: carbon negative :: biomass :: bioenergy ::
Professor Chris Rapley, Director of British Antarctic Survey makes the point on the need to limit our reliance on fossil fuels: "Since the beginning of the industrial revolution the world's oceans have absorbed about a quarter of the 500 gigatons of carbon emitted into the atmosphere by humans. The possibility that in a warmer world the Southern Ocean - the strongest ocean sink - is weakening is a cause for concern."
The saturation of the Southern Ocean was revealed by scrutinising observations of atmospheric CO2 from 40 stations around the world. Since 1981 the Southern Ocean sink ceased to increase, whereas CO2 emissions increased by 40%.
Dr Paul Fraser, who leads research into atmospheric greenhouse gases at Australia's CSIRO Marine and Atmospheric Research, says the international team’s four-year study concludes that the weakening is due to human activities.
“The researchers found that the Southern Ocean is becoming less efficient at absorbing carbon dioxide due to an increase in wind strength over the Ocean, resulting from human-induced climate change,” Dr Fraser says.
“The increase in wind strength is due to a combination of higher levels of greenhouse gases in the atmosphere and long-term ozone depletion in the stratosphere, which previous CSIRO research has shown intensifies storms over the Southern Ocean.”
The increased winds influence the processes of mixing and upwelling in the ocean, which in turn cause an increased release of carbon dioxide into the atmosphere, reducing the net absorption of carbon dioxide into the ocean.
More information:
Corinne Le Quéré, et al., Saturation of the Southern Ocean CO2 Sink Due to Recent Climate Change, Science, Published Online May 17, 2007, Science DOI: 10.1126/science.1136188
Eurekalert: Climate change affects Southern Ocean carbon sink - May 18, 2007.
CSIRO: Southern ocean carbon sink weakened - May 18, 2007.
Article continues
Friday, May 18, 2007
Researchers improve bio-oil refining, aim for carbon negative production system
The group's findings [*abstract] are detailed in the early online edition of the American Chemical Society journal Energy and Fuels. Tom Adams, author and director of the UGA Faculty of Engineering outreach service, explains that scientists have long been able to derive oils from wood, but they had been unable to process it effectively or inexpensively so that it can be used in conventional engines. The researchers have developed a new chemical process, which they are working to patent, that inexpensively treats the oil so that it can be used straight in unmodified diesel engines or blended with biodiesel and petroleum diesel.
The new process works as follows: wood chips and pellets - roughly a quarter inch in diameter and six-tenths of an inch long - are heated in the absence of oxygen at a high temperature, a process known as pyrolysis. Up to a third of the dry weight of the wood becomes charcoal, while the rest becomes a gas. Most of this gas is condensed into a liquid bio-oil and chemically treated. When the process is complete, about 34 percent of the bio-oil (or 15 to 17 percent of the dry weight of the wood) can be used to power engines. The researchers are currently working to improve the process to derive even more oil from the wood.
Towards carbon-negative biofuels
Adams points out that the pyrolysis system offers an opportunity to make biofuels radically carbon-negative, meaning that they do not merely reduce heat-trapping carbon dioxide in the atmosphere, but actually take more of it out than they release (see: "Biochar soil sequestration and pyrolysis most climate-friendly way to use biomass for energy"). As long as new trees are planted to replace the ones used to create the fuel, the biofuel is carbon-neutral. But if the charcoal fraction obtained from pyrolysis is stored as a fertilizer in soils, then the biofuel becomes carbon-negative:
bioenergy :: biofuels :: energy :: sustainability :: wood :: biomass :: pyrolysis :: bio-oil :: biochar :: charcoal :: terra preta :: carbon sequestration :: carbon-negative ::
The researchers have created test plots to explore whether the charcoal can indeed be used as a fertilizer. If the economics work for the charcoal fertilizer, going carbon negative becomes a very green option.
The idea of storing "bio-char" or "carbon black" into soils is thousands of years old. Scientists working in the Amazon and in the West African rainforest found that native populations had been using the technique of sequestring charcoal in soils for millennia. Such "terra preta" or "dark earth" plots are surprisingly fertile compared to non-treated soils (earlier post). The technique is currently receiving a lot of attention from the renewable energy community and from climate scientists alike, because it promises to offer a reliable and affordable method to reduce carbon dioxide emissions. The process could be implemented on a vast scale in low-fertility and problematic soils across the tropics and the subtropics.
But more research is needed. As Adams says, although the new biofuel with carbon negative potential has performed well, further tests will allow the researchers to assess its long-term impact on engines, its emissions characteristics and the best way to transport and store it. "It's going to take a while before this fuel is widely available", Adams said. "We've just started on developing a new technology that has a lot of promise."
The research was funded by the U.S. Department of Energy, the Georgia Traditional Industries Pulp and Paper Research Program and the State of Georgia upon the recommendation of the Governor's Agriculture Advisory Committee.
More information:
Manuel Garcia-Perez, Thomas T. Adams, John W. Goodrum, Daniel P. Geller, and K. C. Das, "Production and Fuel Properties of Pine Chip Bio-oil/Biodiesel Blends" [*abstract], Energy and Fuels, May 18, 2007, ASAP Article 10.1021/ef060533e S0887-0624(06)00533-0.
University of Georgia: New biofuel from trees developed at UGA: Still-unnamed fuel can be blended with biodiesel, petroleum diesel - May 18, 2007.
Article continues
posted by Biopact team at 5:57 PM 1 comments links to this post