Could Acidification of the Oceans Be the Most Irreversible Consequence of Climate Change?

In 2004 the Royal Society, the United Kingdom’s national academy of science, launched an investigation of growing ocean acidity and its potential implications for humanity and ecosystems. With 20 to 25 million tons of carbon dioxide being added to the world’s oceans each day it is projected that the pH of the oceans may drop about 0.5 units by 2100, moving to a much more acidic state. Drawing on the work of nine of the world’s leading ocean scientists, the Royal Society in releasing the Working Group’s Report noted:

"Evidence indicates that emissions of carbon dioxide from human activities over the past 200 years have already led to a reduction in the average pH of surface seawater of 0.1 units and could fall by 0.5 units by the year 2100. This pH is probably lower than has been experienced for hundreds of millennia and, critically, at a rate of change probably 100 times greater than at any time over this period."

The whole Report is available here.

An October 5 American Meteorological Seminar at the Dirksen Senate Office Building heard from two of the world’s leading researchers on this issue: Dr, Richard A, Feely, Supervisory Oceanographer of NOAA’s Pacific Marine Environmental Laboratory in Seattle, Washington, and Dr. Kenneth Caldeira of the Department of Global Ecology, Carnegie Institution, Stanford University, himself a member of the Royal Society Working Group.

Although delivered with the caution characteristic of leading scientific researchers, the presentations now on line at the American Meteorological Society site pointed to the likelihood of mass extinctions of coral well before the end of the current century and large-scale disruption of the entire marine food chain. At this point it is not possible to project the precise implications for global food security, but the projections would suggest this could be a grave concern, particularly as fisheries are already being squeezed by various factors including over fishing.

What was perhaps the most striking aspect of the projections was the long recovery time from acidification of the oceans — on the order of ten thousand years or more. Many changes to the terrestrial environment caused by climate change - sea level rise related inundation and erosion, and in some regions forest dieback- can be ameliorated or adapted to by sometimes heroic measures within decades or centuries. The time frame in recovering from a great increase in ocean acidity is likely to be several orders of magnitude longer.