The slow and inevitable destruction of the ocean

The June 18, 2010 issue of Science contains a chilling summary by Scott C. Doney of the poisoning of our oceans. In an article entitled “The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry” (abstract; article behind pay wall) Doney attempts a comprehensive review of the chemical alteration of the ocean caused by human activities including carbon emissions and pollution from fertilizers and industrial activities. Doney is a marine geochemist at the Woods Hole Oceanographic Institution (WHOI). The WHOI news release quotes him as saying “that climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and the many forms of pollution are ‘altering fundamentally the … ocean, often on a global scale and, in some cases, at rates greatly exceeding those in the historical and recent geological record.’” It summarizes his findings:

  • Global ocean pH and chemical saturation states are changing at an “unprecedented” rate, 30 to 100 times faster than temporal changes in the recent geological past, “and the perturbations will last many centuries to millennia.”
  • “Ocean acidification will likely reduce shell and skeleton growth by many marine calcifying species, including corals and mollusks.”
  • “Ocean acidification may also reduce the tolerance of some species to thermal stress … Polar ecosystems may be particularly susceptible…”
  • Fertilizer runoff and nitrogen from fossil fuels are increasing the severity and duration of coastal hypoxia, or decreased oxygen.

It is perhaps common knowledge that increased carbon dioxide in the atmosphere has resulted in the “acidification” of the ocean: The ocean “absorbs” carbon dioxide from the atmosphere, possibly as much as one-third of the amount added. Dissolved carbon dioxide produces carbonic acid, dissociation of which yields hydrogen ions and a bicarbonate alkalinity, the anion (HCO3-). The pH of the ocean drops as the concentration of carbon dioxide increases. What is now learned is that the acidification is increasing faster than previously expected. The February 2009 issue of Scientific American described this alarming news:

“Marine ecologist J. Timothy Wootton of the University of Chicago and his colleagues spent eight years compiling measurements of acidity, salinity, temperature and other data from Tatoosh Island off the northwestern tip of Washington State. They found that the average acidity rose more than 10 times faster than predicted by climate simulations.”

Doney himself has been one of the more prominent in publicizing the dire consequences of ocean acidification. In March 2006 he wrote a popular article on “The Dangers of Ocean Acidification” (behind pay wall). The most apparent effect is that it can dissolve the calcium carbonate in shells of creatures such as corals and mollusks.

The increased carbon input is only one of the dangers Doney describes. Increased nitrogen input (from fertilizer runoff, among other things) and industrial pollution (including mercury) have profoundly disturbing effects on the ocean chemistry and ultimately ecosystems, particularly by reducing the dissolved oxygen content of coastal waters (as a result of the organic use of increased nutrients) and introduction of toxins into the food chain (for example, mercury, which cannot be eliminated by organisms, and therefore results in increasing concentration in animal tissue over time as it is recycled in the food chain).

Even more alarming is that efforts to reduce atmospheric carbon output have not produced visible effects; quite the contrary:

“’Over the last decade, CO2 emissions have continued to climb despite efforts to control emissions,’ Doney said.  ‘Preliminary evidence suggests that the land and ocean may be becoming less effective at removing CO2 from the atmosphere, which could accelerate future climate change.’” [WHOI press release.]

Doney concludes that there isn’t even sufficient means for determining the change in the ocean. In the Science paper he explains the need for “a deeper understanding of human impacts on ocean biogeochemistry…Although some progress has been made on a nascent ocean observing system for CO2, the marine environment remains woefully undersampled for most compounds. The oceanographic community needs to develop a coordinated observational plan …”

Needless to say, at a time when scientific news about human impact on the planet is almost never cheerful, a detailed synthesis of the state of knowledge, such as Doney has produced, is quite distressing. The disconnect between the state of scientific knowledge (even though the extent of the danger is incomplete) and the state of public discourse on solutions (or even whether solutions are necessary!) is sufficient ground for a profoundly pessimistic view of the future of mankind.


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