Archive for November, 2006

Sour sea change

The oceans are in danger, and we are responsible.

It’s more than a matter of overfishing, global warming, rising sea levels and catastrophic current changes, though we have had a hand it that.

Scores of scientists have been studying and monitoring the effects of carbon dioxide on the ocean’s waters. And the news is not good…

Trenton Times, 26 November 2006. Article.

Large accumulation of anthropogenic CO2 in the East (Japan) Sea and its significant impact on carbonate chemistry

This paper reports on a basin-wide inventory of anthropogenic CO2 in the East (Japan) Sea determined from high-quality alkalinity, chlorofluorocarbon, and nutrient data collected during a summertime survey in 1999 and total dissolved inorganic carbon data calculated from pH and alkalinity measurements. The data set comprises measurements from 203 hydrographic stations and covers most of the East Sea with the exception of the northwestern boundary region. Anthropogenic CO2 concentrations are estimated by separating this value from total dissolved inorganic carbon using a tracer-based (chlorofluorocarbon) separation technique. Wintertime surface CFC-12 data collected in regions of deep water formation off Vladivostok, Russia, improve the accuracy of estimates of anthropogenic CO2 concentrations by providing improved air-sea CO2 disequilibrium values for intermediate and deep waters. Our calculation yields a total anthropogenic CO2 inventory in the East Sea of 0.40 ± 0.06 petagrams of carbon as of 1999. Anthropogenic CO2 has already reached the bottom of the East Sea, largely owing to the effective transport of anthropogenic CO2 from the surface to the ocean interior via deep water formation in the waters off Vladivostok. The highest specific column inventory (vertically integrated inventory per square meter) of anthropogenic CO2 of 80 mol C m−2 is found in the Japan Basin (40°N−44°N). Comparison of this inventory with those for other major basins of the same latitude band reveal that the East Sea values are much higher than the inventory for the Pacific Ocean (20−30 mol C m−2) and are similar to the inventory for the North Atlantic (66−72 mol C m−2). The substantial accumulation of anthropogenic CO2 in the East Sea during the industrial era has caused the aragonite and calcite saturation horizons to move upward by 80−220 m and 500−700 m, respectively. These upward movements are approximately 5 times greater than those found in the North Pacific. Both the large accumulation of anthropogenic CO2 and its significant impact on carbonate chemistry in the East Sea suggest that this sea is an important site for monitoring the future impact of the oceanic invasion of anthropogenic CO2.

Park, G.-H., K. Lee, P. Tishchenko, D.-H. Min, M. J. Warner, L. D. Talley, D.-J. Kang, and K.-R. Kim, 2006. Large accumulation of anthropogenic CO2 in the East (Japan) Sea and its significant impact on carbonate chemistry. Global Biogeochemical Cycles 20, GB4013, doi:10.1029/2005GB002676. Article.

The Darkening Sea

Elizabeth Kolbert reports on the impact of carbon-dioxide emissions on the ocean, which is resulting in “ocean acidification” and threatening the entire marine ecosystem (“The Darkening Sea,” p. 66). Kolbert explains that acidification is caused by the decrease in the ocean’s pH level due to its uptake of carbon dioxide, or CO2, noting that the ocean, which covers seventy per cent of the earth’s surface, absorbs and releases gases from and into the atmosphere at roughly equal rates. “But change the composition of the atmosphere, as we have done, and the exchange becomes lopsided: more CO2 from the air enters the water than comes back out,” she writes. Kolbert reports that humans have already pumped some hundred and twenty billion tons of carbon into the oceans, to produce a .1 decline in surface pH, which represents a rise in acidity of roughly thirty per cent. “This year alone, the seas will absorb another 2 billion tons of carbon, and next year it is expected that they will absorb another 2 billion tons,” Kolbert reports. “Every day, every American, in effect, adds forty pounds of carbon dioxide to the oceans.” Kolbert writes, “Because of the slow pace of deep-ocean circulation and the long life of carbon dioxide in the atmosphere, it is impossible to reverse the acidification that has already taken place. Nor is it possible to prevent still more from occurring. Even if there were some way magically to halt the emission of CO2 tomorrow, the oceans would continue to take up carbon until they reached a new equilibrium with the air. . . . Humans have, in this way, set in motion change on a geological scale. The question that remains is how marine life will respond.”

The New Yorker, 20 November 2006. Web site.

Model Simulations of Carbon Sequestration in the Northwest Pacific by Patch Fertilization

Iron fertilization of nutrient-rich surface waters of the ocean is one possible way to help slow the rising levels of atmospheric CO2 by sequestering it in the oceans via biological carbon export. Here, I use an ocean general circulation model to simulate a patch of nutrient depletion in the subpolar northwest Pacific under various scenarios. Model results confirm that surface fertilization is an inefficient way to sequester carbon from the atmosphere (Gnanadesikan et al., 2003), since only about 20% of the exported carbon comes initially from the atmosphere. Fertilization reduces future production and thus CO2 uptake by utilizing nutrients that would otherwise be available later. Effectively, this can be considered as leakage when compared to a control run. This “effective” leakage and the actual leakage of sequestered CO2 cause a significant, rapid decrease in carbon retention (only 30-45% retained after 10 years and less than 20% after 50 years). This contrasts markedly with the almost 100% retention efficiency for the same duration using the same model, when carbon is disposed directly into the northwest Pacific (Matsumoto and Mignone, 2005). As a consequence, the economic effectiveness of patch fertilization is poor in two limiting cases of the future price path of carbon. Sequestered carbon in patch fertilization is lost to the atmosphere at increasingly remote places as time passes, which would make monitoring exceedingly difficult. If all organic carbon from one-time fertilization reached the ocean bottom and remineralized there, acidification would be about -0.05 pH unit with O2 depletion about -20 mmol kg-1. These anomalies are probably too small to seriously threaten deep sea biota, but they are underestimated in the model because of its large grid size. The results from this study offer little to advocate purposeful surface fertilization as a serious means to address the anthropogenic carbon problem.

Matsumoto M., 2006. Model Simulations of Carbon Sequestration in the Northwest Pacific by Patch Fertilization. Journal of Oceanography, 62(6):887-902. Article.

Cyanobacterial calcification, carbon dioxide concentrating mechanisms, and Proterozoic-Cambrian changes in atmospheric composition

Photosynthetic uptake of inorganic carbon can raise the pH adjacent to cyanobacterial cells, promoting CaCO3 precipitation. This effect is enhanced by CO2 concentrating mechanisms that actively transport HCO3- into cells for carbon fixation. CO2 concentrating mechanisms presumably developed in response to atmospheric decrease in CO2 and increase in O2 over geological timescales. In present-day cyanobacteria, CO2 concentrating mechanisms are induced when the atmospheric partial pressure of CO2 (pCO2) falls below ~0.4%. Reduction in pCO2 during the Proterozoic may have had two successive effects on cyanobacterial calcification. First, fall in pCO2 below ~1% (33 times present atmospheric level, PAL) resulted in lower dissolved inorganic carbon (DIC) concentrations that reduced pH buffering sufficiently for isolated CaCO3 crystals to begin to nucleate adjacent to cyanobacterial cells. As a result, blooms of planktic cyanobacteria induced precipitated ‘whitings’ of carbonate mud in the water column whose sedimentary accumulation began to dominate carbonate platforms ~1400–1300 Ma. Second, fall in pCO2 below ~0.4% (10 PAL) induced CO2-concentrating mechanisms that further increased pH rise adjacent to cells and promoted in vivo cyanobacterial sheath calcification. Crossing of this second threshold is indicated in the fossil record by the appearance of Girvanella 750–700 Ma. Coeval acquisition of CO2 concentrating mechanisms by planktic cyanobacteria further stimulated whiting production. These inferences, that pCO2 fell below ~1% ~1400–1300 Ma and below ~0.4% 750–700 Ma, are consistent with empirical and modelled palaeo-atmosphere estimates. Development of CO2 concentrating mechanisms was probably temporarily slowed by global cooling ~700–570 Ma that favoured diffusive entry of CO2 into cells. Lower levels of temperature and DIC at this time would have reduced seawater carbonate saturation state, also hindering cyanobacterial calcification. It is suggested that as Earth emerged from ‘Snowball’ glaciations in the late Neoproterozoic, global warming and O2 rise reactivated the development of CO2 concentrating mechanisms. At the same time, rising levels of temperature, calcium ions and DIC increased seawater carbonate saturation state, stimulating widespread cyanobacterial in vivo sheath calcification in the Early Cambrian. This biocalcification event promoted rapid widespread development of calcified cyanobacterial reefs and transformed benthic microbial carbonate fabrics.

Riding R., 2006. Cyanobacterial calcification, carbon dioxide concentrating mechanisms, and Proterozoic–Cambrian changes in atmospheric composition. Geobiology 4(4), 299-316. Article.

Coral bleaching will hit the world’s poor

… Climate change is responsible for increased sea surface temperatures and ocean acidification – due to higher levels of dissolved CO2 – which lead to increased mass coral bleaching and mortality, reduced growth of corals and weakened animal skeletons. More acid ocean waters have already reduced coral reef calcification, and therefore growth rates and structural strength of coral skeletons, by 30 percent.

IUCN press release, 17 November 2006.

Significant long-term increase of fossil fuel CO2 uptake from reduced marine calcification

Analysis of available plankton manipulation experiments demonstrates a previously unrecognized wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat” of planktic calcifiers, Emiliania huxleyi not representative of calcification generally. We assess the implications of the experimental uncertainty in plankton calcification response by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response. We predict a substantial future reduction in marine carbonate production, with ocean CO2 sequestration across the model ensemble enhanced by between 62 and 199 PgC by the year 3000, equivalent to a reduction in the atmospheric fossil fuel CO2 burden at that time of up to 13%. Concurrent changes in ocean circulation and surface temperatures contribute about one third to the overall importance of reduced plankton calcification.

Ridgwell A., Zondervan I, Hargreaves J. C. , Bijma J., Lenton T. M., 2006.  Significant long-term increase of fossil fuel CO2 uptake from reduced marine calcification. Biogeosciences Discussions, 3, 1763-1780, 2006. Article.

Oceanic implications for climate change policy

Under the United Nations convention on the law of the sea (1982), each participating country maintains exclusive economic and environmental rights within the oceanic region extending 200 nm from its territorial sea, known as the exclusive economic zone (EEZ). Although the ocean within each EEZ is undoubtedly an anthropogenic CO2 sink, it has been over-looked within international climate policy. In this paper I use an area-weighted scaling argument to show that the inclusion of the EEZ CO2 sink within national carbon accounts would have significant implications in tracking national greenhouse commitments to any future climate change policy initiative. The advantages and disadvantages for inclusion of the EEZ CO2 sink into global climate change policy are also explored. The most compelling argument for including the EEZ CO2 sink is that it would enhance the equity and resources among coastal nations to combat and adapt against future climate change that will inherently impact coastal nations more so than land locked nations. If included, the funds raised could be used for either monitoring or adaptive coastal infrastructure among the most vulnerable nations. On the other hand, the EEZ anthropogenic CO2 sink cannot be directly controlled by human activities and could be used as a disincentive for some developed nations to reduce fossil-fuel related greenhouse gas emissions. This may therefore dampen efforts to ultimately reduce atmospheric greenhouse gas concentrations. In consideration of these arguments it is therefore suggested that an “EEZ clause” be added to Kyoto and any future international climate policy that explicitly excludes its use within national carbon accounts under these international climate frameworks.
McNeil BI, 2006. Oceanic implications for climate change policy. Environmental Science & Policy 7(9):595-606. Article.

CO2 Sensing at Ocean Surface Mediated by cAMP in a Marine Diatom

Marine diatoms are known to be responsible for about a quarter of global primary production and their photosynthesis is sustained by inorganic carbon-concentrating mechanisms and/or C4 metabolism. Activities of the inorganic carbon-concentrating mechanism are attenuated under enriched [CO2]; however, impacts of this factor on primary productivity and the molecular mechanisms of CO2 responses in marine diatoms are unknown. In this study, transgenic cells were generated of the marine diatom Phaeodactylum tricornutum by the introduction of a beta-glucuronidase reporter gene under the control of an intrinsic CO2-responsive promoter, which is the sequence between –80 to +61 relative to the transcription start site of a chloroplastic-carbonic anhydrase gene, ptca1, obtained from P. tricornutum. The activity of the ptca1 promoter was effectively repressed in air-level CO2 by treating cells with a 1.0 mM cAMP analog, dibutyryl cAMP, or a cAMP phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine. Deletion of the intrinsic cAMP-response element from the ptca1 promoter caused a lack of repression of the reporter gene uidA, even under elevated [CO2] and a null phenotype to the strong repressive effects of dibutyryl cAMP and 3-isobutyl-1-methylxanthine on the ptca1 promoter. Deletion of the cAMP-response element was also shown to cause derepression of the uidA reporter gene in the dark. These results indicate that the cytosolic cAMP level increases under elevated [CO2] and represses the ptca1 promoter. This strongly suggests the participation of cAMP metabolism, presumably at the cytosolic level, in controlling CO2-acquisition systems under elevated [CO2] at the ocean surface in a marine diatom.

Harada H., Nakajima K., Sakaue K., Matsuda Y. CO2 sensing at ocean surface mediated by cAMP in a marine diatom. Plant Physiol. 142: 1318-1328. Article.

Expert Says Oceans Are Turning Acidic

NAIROBI, Kenya — The world’s oceans are becoming more acidic, which poses a threat to sea life and Earth’s fragile food chain, a climate expert said Thursday.

Oceans have already absorbed a third of the world’s emissions of carbon dioxide, one of the heat-trapping gases blamed for global warming, leading to acidification that prevents vital sea life from forming properly.

“The oceans are rapidly changing,”said professor Stefan Rahmstorf on the sidelines of a U.N. conference on climate change that has drawn delegates from more than 100 countries to Kenya.”Ocean acidification is a major threat to marine organisms.”

FOXNews.com, 9 Novembre 2006. Article.

Online Event – Ocean Acidification

On November 13th-14th, 2006, The World Ocean Observatory will present an online, interactive web-cast on Ocean Acidification. This is a unique opportunity for students, educators and interested individuals to participate in the first demonstration of an ongoing series of global online events to explore ocean issues. Those who attend this 45 minute event hosted in Australia will participate in a real-time interactive presentations and discussions with leading scientists around the world.

More information: The World Ocean Observatory

Effects of anthropogenic seawater acidification on acid–base balance in the sea urchin Psammechinus miliaris

The purple-tipped sea urchin, Psammechinus miliaris, was exposed to artificially acidified seawater treatments (pHw 6.16, 6.63 or 7.44) over a period of 8 days. Urchin mortality of 100% was observed at pHw 6.16 after 7 days and coincided with a pronounced hypercapnia in the coelomic fluid producing an irrecoverable acidosis. Coelomic fluid acid–base measures showed that an accumulation of CO2 and a significant reduction in pH occurred in all treatments compared with controls. Bicarbonate buffering was employed in each case, reducing the resultant acidosis, but compensation was incomplete even under moderate environmental hypercapnia. Significant test dissolution was inferred from observable increases in the Mg2+ concentration of the coelomic fluid under all pH treatments. We show that a chronic reduction of surface water pH to below 7.5 would be severely detrimental to the acid–base balance of this predominantly intertidal species; despite its ability to tolerate fluctuations in pCO2 and pH in the rock pool environment. The absence of respiratory pigment (or any substantial protein in the coelomic fluid), a poor capacity for ionic regulation and dependency on a magnesium calcite test, make echinoids particularly vulnerable to anthropogenic acidification. Geological sequestration leaks may result in dramatic localised pH reductions, e.g. pH 5.8. P. miliaris is intolerant of pH 6.16 seawater and significant mortality is seen at pH 6.63.

Miles et al., in press. Effects of anthropogenic seawater acidification on acid–base balance in the sea urchin Psammechinus miliaris. Marine Pollution Bulletin. Article.

Dropping pH in the Oceans Causing a Rising Tide of Alarm

One of the most unexpected consequences of global climate change may well turn out to be one of the most severe in terms of impacts on life on earth. As continued carbon emissions accelerate global warming, the carbon dioxide contained in those emissions is able to silently yet dramatically reduce the alkalinity of the oceans. And as the pH drops, marine organisms that produce shells and carbonate skeletons grow weak and die off.

The discovery that carbon dioxide emissions can lower global ocean pH is very recent, even though chemists and biologists have for long known that when carbon dioxide dissolves in water, carbonic acid results. However, the sheer volume of water in the oceans has always been assumed to be so vast as to be safe from changes in chemical balance brought about by small scale inputs. In effect, it is just plain hard to imagine that atmospheric inputs of any kind could significantly alter the chemical composition and nature of over 1.3 trillion cubic kilometers of ocean water. Thus when intrepid oceanographers and marine ecologists set out to address the question of how changing atmospheric conditions that lead to changes in pH could affect marine life, they raised alarms about the possibilities of very large scale impacts.

Tundi Agardy, The W2O Observer. Article.

Apocalypse now

Sir Nicholas Stern was commissioned by British Chancellor Gordon Brown to write a landmark report on climate change, amid growing fears about the human and economic cost of global warming. Stern, an internationally regarded economist, spent more than a year examining the complex problem. After a week of rumours and leaks, on October 30 he formally launched his 579-page report. Though dry in its delivery, it had a simple and apocalyptic message: climate change is fundamentally altering the planet; the risks of inaction are high; and time is running out. This is a summary of the key findings.

David Adam and Larry Elliott, Mail & Guardian Online, 2 November 2006. Article

Scandal below the surface

By NICHOLAS D. KRISTOF

The New York Times, 31 October 2006. Article.
The crucial issue this year is Iraq, and the most important issue this decade may be the risk that nuclear proliferation results in the incineration of Wall Street by terrorists. Both topics are spurring useful debate this campaign season.

But one of the more important issues this century is generating no serious discussion on the campaign trail. And, in place of a drumroll, let’s look at the chemistry experiment in which we’re all taking part.

If you think of the earth’s surface as a great beaker, then it’s filled mostly with ocean water. It is slightly alkaline, and that’s what creates a hospitable home for fish, coral reefs and plankton — and indirectly, higher up the food chain, for us.

But scientists have discovered that the carbon dioxide we’re spewing into the air doesn’t just heat up the atmosphere and lead to rising seas. Much of that carbon is absorbed by the oceans, and there it produces carbonic acid — the same stuff found in soda pop.

That makes oceans a bit more acidic, impairing the ability of certain shellfish to produce shells, which, like coral reefs, are made of calcium carbonate. A recent article in Scientific American explained the indignity of being a dissolving mollusk in an acidic ocean: “Drop a piece of chalk (calcium carbonate) into a glass of vinegar (a mild acid) if you need a demonstration of the general worry: the chalk will begin dissolving immediately.”

The more acidic waters may spell the end, at least in higher latitudes, of some of the tiniest variations of shellfish — certain plankton and tiny snails called pteropods. This would disrupt the food chain, possibly killing off many whales and fish, and rippling up all the way to humans.

We stand, so to speak, on the shoulders of plankton.

“There have been a couple of very big events in geological history where the carbon cycle changed dramatically,” said Scott Doney, senior scientist at the Woods Hole Oceanographic Institution in Massachusetts. One was an abrupt warming that took place 55 million years ago in conjunction with acidification of the oceans and mass extinctions. Most scientists don’t believe we’re headed toward a man-made variant on that episode — not yet, at any rate. But many worry that we’re hurtling into unknown dangers.

“Whether in 20 years or 100 years, I think marine ecosystems are going to be dramatically different by the end of this century, and that’ll lead to extinction events,” Mr. Doney added.

“This is the only habitable planet we have,” he said. “The damage we do is going to be felt by all the generations to come.”

So that should be one of the great political issues for this century — the vandalism we’re committing to our planet because of our refusal to curb greenhouse gases. Yet the subject is barely debated in this campaign.

Changes in ocean chemistry are only one among many damaging consequences of carbon emissions. Evidence is also growing about the more familiar dangers: melting glaciers, changing rainfall patterns, rising seas and more powerful hurricanes.

Last year, the World Health Organization released a study indicating that climate change results in an extra 150,000 deaths and five million sicknesses each year, by causing the spread of malaria, diarrhea, malnutrition and other ailments.

A report prepared for the British government and published yesterday, the Stern Review on the Economics of Climate Change, warned that inaction “could create risks of major disruption to economic and social activity, on a scale similar to those associated with the great wars and the economic depression of the first half of the 20th century.”

If emissions are not curbed, climate change will cut 5 percent to 20 percent of global G.D.P. each year, declared the mammoth report. “In contrast,” it said, “the costs of action — reducing greenhouse gas emissions to avoid the worst impacts of climate change — can be limited to around 1 percent of global G.D.P. each year.” Some analysts put the costs of action higher, but most agree that it makes sense to invest far more in alternative energy sources, both to wean ourselves of oil and to reduce the strain on our planet.

We know what is needed: a carbon tax or cap-and-trade system, a post-Kyoto accord on emissions cutbacks, and major research on alternative energy sources. But as The Times’s Andrew Revkin noted yesterday, spending on energy research and development has fallen by more than half, after inflation, since 1979.

Melting glaciers and corroding pteropods aren’t as sensational as a Congressional page scandal, or as urgent as the Iraq war. But they are just as scandalous. We have no responsibility greater than as stewards of our planet, and we’re blowing it.

We’ll pay the price later for abusing Earth now

… But one of the more important issues this century is generating no serious discussion on the campaign trail. And in place of a drumroll, let’s look at the chemistry experiment in which we’re all taking part.

If you think of the earth’s surface as a great beaker, then it’s filled mostly with ocean water. It is slightly alkaline, and that’s what creates a hospitable home for fish, coral reefs and plankton — and indirectly, higher up the food chain, for us. But scientists have discovered that the carbon dioxide we’re spewing into the air doesn’t just heat up the atmosphere and lead to rising seas. Much of that carbon is absorbed by the oceans, and there it produces carbonic acid — the same stuff found in soda pop. That makes oceans a bit more acidic, impairing the ability of certain shellfish to produce shells

Kansas City Star, 1st November 2006. Article.

Under-threat coral reefs get protection strategy

A new report has outlined a strategy to protect the world’s declining coral reefs. Covering just 0.2 per cent of the ocean floor, the reefs are home to 25 per cent of marine species globally. They also provide livelihoods to 100 million people and the basis for industries such as tourism and fishing, which are worth an annual net benefit of $US 30 billion (£16 billion). But climate change is threatening these tropical ecosystems; 20 per cent have already been wrecked and a further 50 per cent are facing immediate or long-term danger of collapse due to increases in sea temperature and ocean acidification.

inthenews.co.uk, 1st November 2006. Article.

Building Resilience May Help Corals, Mangroves Survive

GENEVA, Switzerland, October 31, 2006 (ENS) – Survival strategies for coral reefs and mangroves threatened by climate change are outlined by scientists of IUCN-World Conservation Union and the Nature Conservancy in two new publications launched today. The strategies rely on managing stressors other than global warming so that corals and mangroves are more resilient and able to survive in a warming world.

Climate change is destroying tropical marine ecosystems through sea temperature increase and ocean acidification. Scientists say 20 percent of the world’s coral reefs have already been ruined and a further 50 percent are facing immediate or long term danger of collapse.

Environment News Service, 1st November 2006. Article.


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