Archive for December, 2008

A sea of troubles

Man is assaulting the oceans. They will smite him if he does not take care

Not much is known about the sea, it is said; the surface of Mars is better mapped. But 2,000 holes have now been drilled in the bottom, 100,000 photographs have been taken, satellites monitor the five oceans and everywhere floats fitted with instruments rise and fall like perpetual yo-yos. Quite a lot is known, and very little is reassuring.
The worries begin at the surface, where an atmosphere newly laden with man-made carbon dioxide interacts with the briny. The sea has thus become more acidic, making life difficult, if not impossible, for marine organisms with calcium-carbonate shells or skeletons. These are not all as familiar as shrimps and lobsters, yet species like krill, tiny shrimp-like creatures, play a crucial part in the food chain: kill them off, and you may kill off their predators, whose predators may be the ones you enjoy served fried, grilled or with sauce tartare. Worse, you may destabilise an entire ecosystem.
That is also what acidification does to coral reefs, especially if they are already suffering from overfishing, overheating or pollution. Many are, and most are therefore gravely damaged. Some scientists believe that coral reefs, home to a quarter of all marine species, may virtually disappear within a few decades. That would be the end of the rainforests of the seas.

So far, the rising sea levels, dying corals and spreading algal blooms are only minor distractions for most people. A few more hurricanes like Katrina, a few dramatic floods in the coastal cities of the rich world, perhaps even the shutting down of a part of the world’s great conveyor belt of ocean currents, especially if it were the one that warms up western Europe: any of these would catch the attention of policymakers. The trouble is that by then it may be too late.

Continue reading ‘A sea of troubles’

Breakthrough of the year, areas to watch: Ocean fizz

Acidification of the oceans driven by rising atmospheric carbon dioxide continues apace. The falling pH is bad news for sea creatures, from coral reefs to microscopic plankton. But the looming threat has yet to gain a poster child the likes of global warming’s polar bear. Look for a rising tide of studies confirming the pervasive detrimental effects of ocean acidification, although whether more science will grab the public’s attention is problematic.

Continue reading ‘Breakthrough of the year, areas to watch: Ocean fizz’

50 things we didn’t know a year ago

Well, well, well. Wasn’t 2008 a newsy little year?

Believe it or not, stuff happened that had nothing to do with the
presidential election, gas prices or Michael Phelps. Not that you’d
have an easy time sifting through all the media debris to find the
information that actually meant something.

For those and other warm, delicious infomuffins, we humbly present
our list of stuff you know this year that you didn’t know this time
last year. Feel free to unleash these at your New Year’s Eve party:

10. The world’s oceans are growing more acidic at an increasing
rate, a phenomenon that may lead to major disruptions for corals,
lobster, oysters, crabs, mussels and snails, which have difficulty
building their calcium crusts in such conditions.

Continue reading ’50 things we didn’t know a year ago’

The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic

Compositions and abundances of calcareous nannofossil taxa have been determined in a ca 170 kyrs long time interval across the Paleocene/Eocene boundary at 1-cm to 10-cm resolution from two ODP Sites (1262, 1263) drilled along the flank of the Walvis Ridge in the South Atlantic. The results are compared to published data from ODP Site 690 in the Weddell Sea. The assemblages underwent rapid evolution over a 74 kyrs period, indicating stressed, unstable and/or extreme photic zone environments during the PETM hyperthermal. This rapid evolution, which created 5 distinct stratigraphic horizons, is consistent with the restricted brief occurrences of malformed and/or weakly calcified morphotypes. The production of these aberrant morphotypes is possibly caused by major global scale changes in carbon cycling in the ocean-atmosphere system, affecting also photic zone environments. No marked paleoecologically induced changes are observed in abundances of the genera Discoaster, Fasciculithus and Sphenolithus at the Walvis Ridge sites. Surprisingly, there is no significant correlation in abundance between these three genera, presumed to have had a similar paleoecological preference for warm and oligotrophic conditions.

Continue reading ‘The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic’

In situ boron isotope analysis in marine carbonates and its application for foraminifera and palaeo-pH

The boron isotope composition of marine carbonates such as foraminiferal tests and coral skeletons is increasingly being used to reconstruct seawater pH values and atmospheric pCO2 concentrations spanning hundreds of thousands or even millions of years. However, inter specific and small scale (microns) intra specific isotopic variation, either due to life processes of an organism or patchy recrystallisation and dissolution in fossilised material, can limit the use of the boron isotope ratio as palaeo-pH recorder. One approach to address this problem is the combined use of in situ and high spatial resolution mass spectrometry and high precision bulk analytical techniques. While much effort has been invested to establish reference material for silicates little attention has been devoted towards characterizing and using carbonate material allowing direct isotopic comparisons between B isotope data produced on carbonates by different techniques and laboratories. Hence, here we present data on the boron isotope composition of carbonate material determined by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS), thermal ionization mass spectrometry (TIMS), and secondary ionization mass spectrometry (SIMS). The new reference material permits
the B isotope analysis of single foraminiferal chambers using SIMS and to empirically relate between seawater pH, the B isotope composition of O. universa and the predicted foraminiferal vital effect.

Continue reading ‘In situ boron isotope analysis in marine carbonates and its application for foraminifera and palaeo-pH’

Effect of progressive acidification on stable carbon isotope of dissolved inorganic carbon in surface waters

Acidification of surface waters by acid mine drainage (AMD) contamination or atmospheric deposition perturbs the carbonate equilibrium, with unknown effects to the isotope ratio of dissolved inorganic carbon (DIC). We progressively acidified samples of NaHCO3, stream water, groundwater, and spring water contaminated by AMD (AMD spring) to a pH < 3 using H2SO4 under open conditions (exposed to the atmosphere) and closed conditions (isolated from the atmosphere). The δ13CDIC of the acidified samples were enriched by 0.7‰ to 5.0‰ during the HCO3 dehydration phase and depleted by 0.6‰ to 2.3‰ during the phase after HCO3 was exhausted. The δ13CCO2 showed enrichment and depletion trends that were similar to those of DIC. The positive enrichment in δ13CDIC during the HCO3 dehydration phase was driven by 1) kinetic fractionation of CO2 during diffusion, or 2) a combination of fractionation accompanying HCO3 dehydration to CO2(aq) followed by isotopic exchange of carbon between CO2(aq) and HCO3. We conclude that carbon isotope values in conjunction with concentrations of DIC species (CO2(aq), HCO3, and CO32-) can be used to provide evidence for the effects of acidification on DIC in surface waters.

Continue reading ‘Effect of progressive acidification on stable carbon isotope of dissolved inorganic carbon in surface waters’

Acid tests

Researchers warn that the excess carbon dioxide we produce increases the acidity of the oceans much faster than expected. Michael Gross investigates.

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Les océans intoxiqués par le gaz carbonique

L’augmentation continue du CO2 dans l’atmosphère entraîne le réchauffement de la planète mais aussi l’acidification des océans. Certains organismes marins commencent déjà à en souffrir sérieusement.

Continue reading ‘Les océans intoxiqués par le gaz carbonique’

What do we know about climate change?

It seems you can’t open any newspaper these days without seeing the words “climate change” in bold print. Climate change is environmental, social, political and most of all controversial. It is the looming threat on the horizon that may impact the human race in every possible way. Climate change has been highlighted in every form of media and has been displayed in thousands of venues all over the world.

Continue reading ‘What do we know about climate change?’

Fear in the Air, Inc.

A New York Times Op-Ed recently proclaimed that the ocean was becoming more acidic due to the absorption of man-produced carbon dioxide. The concern being that among other calamities, marine life will be endangered due to CO2-produced carbonic acid dissolving the calcium carbonate in the skeletons of corals.

Continue reading ‘Fear in the Air, Inc.’

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Ocean acidification in the IPCC AR5 WG II

OUP book