Ocean acidification

Scott Mandia has a long and devastating post up about ocean acidification, The 800 lb. Gorilla in the Ocean:

When most of us think of climate change and global warming we think of the atmosphere – warmest decades on record recently, atmospheric CO2 at record levels and climbing, increased floods, droughts, hurricanes, melting glaciers, etc. When we do speak about the oceans, it is typically about heat content, Arctic ice melt, and sea level rise. However, the 800 lb. gorilla in the room just might be ocean acidification.

The ocean has absorbed about half of all the anthropogenic (human) carbon emissions since the beginning of the Industrial Revolution (Doney, 2006). The CO2 that the oceans absorb is causing a lower pH which means the oceans are moving toward more acidic conditions. The consequences could be dire.

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The Unknowns:

When one reads Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Future Research, (Kleypas et al., 2006) it becomes quite clear that the impact of ocean acidification on marine life is uncertain because it is essentially a fledgling field. It was not part of the IPCC TAR (2001) however the IPCC Fourth Assessment Report on Climate Change (2007) stated in the Summary for Policy Makers, “The progressive acidification of the oceans due to increasing atmospheric carbon dioxide is expected to have negative impacts on marine shell-forming organisms (e.g. corals) and their dependent species.” Ocean acidification and its impact will be seriously addressed by the Fifth Assessment Report of the IPCC to be released in 2013.

The Knowns:

According to Iglesias-Rodriguez, Doney, Widdicombe, Barry, Caldeira, & Hall-Spencer (2010): “The rate of human-driven ocean acidification is about 100 times faster in the surface ocean than that experienced by marine ecosystems globally for tens of millions of years.”

According to Barry, Schmidt, & Caldeira (2010): “Other than at times of the great mass extinctions, there is no evidence in the geologic record for sustained rates of change in atmospheric CO2 that have been as great or greater than today’s. Even during extreme ocean chemistry changes in geological history- for example, during the Paleocene/Eocene thermal maximum (PETM) 55 million years ago when carbonate minerals dissolved in most of the deep and intermediate ocean-these changes probably happened over several thousands of years. In general, ocean life recovers from extinction episodes by adaptation and evolution of new species, but this takes roughly 10 million years to achieve pre-extinction levels of biodiversity.”

Although much is unknown, it seems clear that humans are altering the oceans in a manner unique to their history and to the history of the marine life within. Just as the grand experiment we are undertaking with the climate, we are doing the same with the oceans. The results of both of these experiments will likely be harmful to life on this planet.

Scott walks the reader through the science of what’s going on and what the ramifications could be for life in the oceans.

Very highly recommended. Please read it yourself and then pass the link on to others, especially those who think that all of the impacts of climate change are caused by increasing temperatures.