By SILKE SCHMIDT
Two independent technical reports published in August 2013 summarize the current state of knowledge about the effects of a changing climate on marine ecosystems. The first is called “Oceans and Marine Resources in a Changing Climate.” It was prepared by more than sixty U.S. scientists and published by the National Oceanic and Atmospheric Administration (NOAA).
The second report specifically examined the consequences of the ocean’s increasing acidity on multiple marine species and was published by Great Britain’s Royal Society. The oceans’ increasing acidity, or decrease in measured pH value, is caused by their uptake of 30-40% of the carbon dioxide released by humans into the atmosphere.
Both reports agree that oceanic acidification affects different organisms very differently. There are expected “winner” and “loser” species, as well as organisms that are quite robust to climate-induced changes. For example, some researchers found that certain worm species are able to adapt and adjust to waters high in carbon dioxide, while closely-related worm species are poisoned by them.
Other researchers demonstrated that tiny ocean organisms called coccolithophores, a type of phytoplankton, maintain their ability to grow calcified shells in more acidic oceans. This finding contradicted earlier studies of shorter duration that reported a failure of coccolithophores to build these plated shells under acidic conditions.
Yet another study highlighted the importance of competition: in carbon dioxide-enriched water, mat-forming algae were the “winners” that outperformed the “losers” corals and kelp.
According to the U.S. report, another consequence of climate change is that the overall species range is shifting toward the poles at a greater rate for marine than terrestrial organisms.