Climate Change Turning Seas Acid

Climate change is turning the oceans more acid in a trend that could endanger everything from clams to coral and be irreversible for thousands of years, national science academies said.

"To avoid substantial damage to ocean ecosystems, deep and rapid reductions of carbon dioxide emissions of at least 50 percent (below 1990 levels) by 2050, and much more thereafter, are needed," the academies said in a joint statement.

The academies said rising amounts of carbon dioxide, the main greenhouse gas emitted mainly by human use of fossil fuels, were being absorbed by the oceans and making it harder for creatures to build protective body parts. The shift disrupts ocean chemistry and attacks the "building blocks needed by many marine organisms, such as corals and shellfish, to produce their skeletons, shells and other hard structures", it said.

On some projections, levels of acidification in 80 percent of Arctic seas would be corrosive to clams that are vital to the food web by 2060, it said. And "coral reefs may be dissolving globally," it said, if atmospheric levels of carbon dioxide were to rise to 550 parts per million (ppm) from a current 387 ppm.
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Truth Behind the Fact...

Increasing use of fossil fuels means more carbon dioxide is going into the air, and most of it will eventually be absorbed by seawater. Once in the water, it reacts to form carbonic acid.

This, in turn, reduces the amount of calcium carbonate in the ocean -- which turns out to be a chemical widely used by marine life.

The acidification of the oceans will ultimately be a temporary state that naturally corrects itself over time. But as we keep pumping CO2 into the sky and the chemistry of the oceans have to keep adjusting to deal with the carbonic acid, life in the oceans could suffer serious decline. The changes occurring in the ocean today are truly extraordinary.This needs immediate attention.

Corals are home to many species of fish. These changes in ocean chemistry are irreversible for many thousands of years, and the biological consequences could last much longer. As acid levels rise in the surface waters, Feeley said, many species of plankton and other creatures at the base of the marine food chain can't develop properly because of the acid-caused decline in calcium carbonate.

Calcification decreases significantly,Many of these species are the primary food sources for juvenile salmon and other important species for mankind. We may be having a very significant impact on the food web.

Most organisms live near the surface, where the greatest pH change would be expected to occur, but deep-ocean lifeforms may be more sensitive to pH changes.

"Coral reefs are like the rain forests of the ocean," noted co-author Chris Langdon, a coral expert at the University of Miami. Acidification of seawater undermines the skeletal structures of coral, Langdon said, which in turn undermines this basic marine ecosystem and harms other species that have evolved to depend upon it.

Coral reefs and other organisms whose skeletons or shells contain calcium carbonate may be particularly affected, the team speculate. They could find it much more difficult to build these structures in water with a lower pH.
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The warning was issued by the Inter-Academy Panel, representing science academies of countries from Albania to Zimbabwe and including those of Australia, Britain, France, Japan and the United States. Martin Rees, president of the Royal Society, the British science academy, said there may be an "underwater catastrophe".

The effects will be seen worldwide, threatening food security, reducing coastal protection and damaging the local economies that may be least able to tolerate it.

In recent years some people have suggested deliberately storing carbon dioxide from power stations in the deep ocean as a way of curbing global warming.

Previously, most experts had looked at ocean absorption of carbon dioxide as a good thing - because in releasing CO2 into the atmosphere we warm the planet; and when CO2 is absorbed by the ocean, it reduces the amount of greenhouse warming.

The academies' statement said that, if current rates of carbon emissions continue until 2050, computer models indicate that "the oceans will be more acidic than they have been for tens of millions of years".

It also urged actions to reduce other pressures on the oceans, such as pollution and over-fishing.
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