Courtesy Mark RyanTwo recent stories in the news highlight environmental issues with Earth’s oceans. The first deals with how the oceans’ pH levels are changing at a much faster rate than normally due to increased levels of carbon dioxide (CO2) in the atmosphere. The second concerns the rise of sea levels due to climate change.
With the first story, Prince Albert II of Monaco and over 150 marine scientists are urging world policymakers to confront the problem of ocean acidification. They stated their concerns in the Monaco Declaration, a document that arose from the 2nd International Symposium on the Ocean in a High-CO2 World held in Monaco last October.
According to the Monaco Declaration, the rapid change in seawater chemistry is already measurable and could by mid-century cause oceans to become inhospitable to coral reefs, inhibit calcification in mussels, plankton, and other calcifying organisms, and subsequently harm the fish population to the extent of causing massive deficits in the food source for millions of people.
The world’s oceans have long acted as buffers against CO2 - absorbing up to a third of it - but are now straining to keep up with rising levels of the greenhouse gas. When CO2 dissolves in seawater it causes pH levels to drop, resulting in a more acidic chemistry. Oceans are 30 percent more acidic than before the Industrial Revolution, and in recent years, researchers at Scripps Oceanography have recorded a drop in the pH from 8.16 to 8.05
The declaration warns that only a serious and immediate reduction in CO2 levels will reverse ocean acidification.
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In the second story, the rise of sea levels due to climate change may actually be a greater threat than previously thought. The potential for rising water from melting ice sheets is not news. Earlier studies have predicted rising ocean levels from the melting of the West Antarctic ice sheet and other ice could, by the end of the century, inundate coastal cities and low-lying areas with up to 3 feet of water.
But previously unrecognized factors are ratcheting up the severity of that number. Authors of a new study say related events triggered by the initial ice melt could cause the sea-levels to rise as much as 21 feet. But it’s really more of a “could happen” rather than a “will happen” situation.
Geophysicist Jerry X. Mitrovica (University of Toronto) and geoscientist Peter Clark (Oregon State) predict not only would the melted ice add more water to the oceans, but also the reduced gravitational pull from the melted (and missing) ice sheet could cause the Antarctic water levels to decrease while northern water levels increased. Also, once the weight of the heavy ice sheet was gone the Antarctic land mass would rebound, pushing more water outward. Finally, the redistribution of water could cause a shift in the Earth’s rotation and potentially push more water northward toward highly populated coastal regions.
University of Toronto physics grad student Natalya Gomez also contributed to the study that appears in the journal Science.