Julia Whitty

Witches' brew: CO2 from water pollution interacts with CO2 from atmosphere in a warming ocean to intensify acidification: Witches: ~Brenda-Starr~. Scallop: walknboston. Anemonefish: lakewentworth. Seahorse: Mr. Mohammed Al Momany | NOAA. Starfish: MikeMurphy. Mashup: Julia WhittyA new kind of witchy interaction is underway in the oceans, report the authors of a new paper in Environmental Science & Technology.

William G. Sunda and Wei-Jun Cai created a model to predict how CO2 from water pollution—that is, runoff from chemical fertilizers (farms), human waste (sewage), and animal waste (feedlots, ranches), plus nitrogen oxide from fossil fuel burning—might interact with the better-known source of CO2 that enters the ocean from the atmosphere, much of it a result of fossil fuel burning.

In either case, too much CO2 entering the ocean lowers the pH of seawater, which raises the acidity of the waters, preventing many marine organisms from getting access to the calcium carbonate needed to make their shells or skeletons. The result, called ocean acidification—sometimes called the "other CO2 problem," global warming being the original—is already impacting commercial oyster beds in the Pacific Northwest. This process has been firmly on the scientific radar for the past 10+ years.

But no one has spent a whole lot of time thinking about the excess CO2 created by water pollution running off the land. Here's what happens. Enriched waters wash off farms, feedlots, and cities to fertilize the ocean. Enough fertilized runoff triggers a cascade of catastrophic events:

• Fertilizing huge algal blooms
• Which lead to massive die-offs of the huge algal blooms
• Which settle to the bottom and feed the growth of bacteria
• Who consume much of the available oxygen in the water and release large amounts of CO2

The result is a dead zone: where oxygen levels are too low (hypoxic) to support most marine life. A good example is the Gulf of Mexico dead zone that "blooms" every spring and summer when the spring and summer rains wash the excess nutrients from the bread basket of the American heartland downstream into the ocean. I wrote more about that here and here.

But there's the excess CO2 of a dead zone too—which also causes ocean acidification. Basically the other other CO2 problem.

So the authors wondered: what happens when you get ocean acidification from the atmosphere mixing with ocean acidification from water pollution?

Their model predicts that rising acidity from water pollution will interact synergistically—that is, more than just the sum of the two sources—with rising acidity from air pollution at intermediate to higher temperatures. Together, the two processes could substantially increase ocean acidification and impact commercial fisheries in places with dead zone problems, like the northern Gulf of Mexico and the Baltic Sea.

Lead author Bill Sunda says: "The largest acidification effects from decaying algal blooms actually occur in colder waters such as those in coastal waters of Northern Europe or Alaska. However, in warmer ocean waters, where the acidification effects from this source are currently smaller, the rising atmospheric CO2 not only lowers the pH (raises the acidity) of the water, but makes the additional acidification effects from decaying algal blooms much worse; i.e., there's a synergistic effect (the effect of the two processes together are more than additive in lowering pH [or are more than multiplicative in raising acidity])."

From the paper:

Thus, while the impact of the two acidification mechanisms by themselves may be moderate in many instances, the combined effect of the two can be much larger. Such large combined acidification effects may cause significant negative impacts on coastal benthic [seafloor] ecosystems that are already stressed by hypoxia and rising water temperatures. Coastal systems support most world finfish production and the overwhelming majority of shellfish production, so the combined negative future impact of these anthropogenic stressors to marine ecosystems and fisheries production could be substantial. However, future impacts will not only be dependent on increasing atmospheric PCO2 [partial pressure of CO2] or the amount of respiratory depletion of O2 [oxygen], but also on temperature and salinity, which will be influenced in the future by a changing climate linked to increasing CO2 in the atmosphere.

 

The bubbling brew of CO2 synergies: Witches: ~Brenda-Starr~. Diagram: Sunda and Cai, ES&T doi: 10.1021/es300626f. Mashup: Julia Whitty

The paper:

William G. Sunda and Wei-Jun Cai. Eutrophication Induced CO2-Acidification of Subsurface Coastal Waters: Interactive Effects of Temperature, Salinity, and Atmospheric PCO2. Environmental Science & Technology (2012). DOI:10.1021/es300626f

 

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Noble Discoverer, Shell's Arctic drill rig: US Coast Guard via Flickr

Shell's comedy-of-errors season of not-drilling in the Arctic drew to a close today as the company announced it was wrapping up ahead of its 24 September deadline.

Shell was hoping that its $4.5 billion investment and multiple years of preparation would allow it to pierce the virgin seafloor of Alaska's Chukchi Sea and squeeze out some of the 22 percent of Earth's undiscovered fossil fuels believed to be underlying the Arctic and recoverable by current technology, according to the USGS.

Here's a list of some of what went awry with Shell's opening season:

1. Their drill ship Noble Discoverer—seriously, that's its name—sailed late from New Zealand. Remember Xena the Princess Warrior, aka Lucy Lawless, occupied the ship briefly in protest in February?
2. The late start ate into a season already shortened by the US Bureau of Ocean Management.
3. En route to the Chukchi Sea, Noble Discoverer ignobly dragged anchor in the port of Dutch Harbor in the Aleutian Islands under only 35mph of wind... a morning breeze in the Arctic.
4. Drilling was delayed again because Shell's primary safety vessel, the oil spill containment barge Arctic Challenger, wasn't still being built in the shipyards in Bellingham, WA.
5. Shell failed to meet some limits on air pollution emissions for its operations set by the EPA.
6. Test drilling (nowhere near a real oil field, because Arctic Challenger wasn't there) finally began on 9 September, nearly two months later than scheduled. "This is an exciting time for Alaska and for Shell," said Royal Dutch Shell on its website. "We look forward to continued drilling progress throughout the next several weeks and to adding another chapter to Alaska's esteemed oil and gas history."
   
7. Noble Discoverer got in 300+ feet of a thin pilot hole—the first drilling offshore in the Alaska Arctic in two decades—before it was halted the next day when a massive iceberg 30 miles long by 12 miles wide came within 105 miles of the drill rig.
8. Also, damagingly, documents obtained by PEER (Public Employees for Environmental Responsibility) under a Freedom of Information Act request showed that original field-testing of the "capping stack"—a containment dome designed to contain a Deepwater Horizon type blowout—deployed on Arctic Challenger took place over a mere two hours on 25 and 26 June and was not verified by anyone other than two officials from the Bureau of Safety and Environmental Enforcement. "The first test merely showed that Shell could dangle its cap in 200ft of water without dropping it," said Kathryn Douglass, a Peer staff lawyer, via The Guardian. "The second test showed the capping system could hold up under laboratory conditions for up to 15 minutes without crumbling.
9. Finally that same "capping stack" was damaged during final testing off Bellingham, Washington, benching it for the remainder of the season... and ending Shell's miserable Noble Discoverer season.

Peter Slaiby, a VP of Shell Alaska, claimed: "The [Arctic] sea conditions in terms of the wind, waves and currents are not even as extreme as the North Sea, although, clearly, there is no ice in the North Sea." Sounds like the prelude to dangerous hubris.

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