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Ocean Acidification Will Exact a Severe Toll on Some Nations

By Lauren Morello, E&E reporter
9/24/2012 12:34:46 PM

Small island states' and coastal African nations' fisheries will be hardest hit by the effects of man-made greenhouse gas emissions, according to a report released today by the environmental group Oceana.

Fishing nets photo courtesy of echiner1

The analysis attempts to determine the 50 nations where climate change and ocean acidification are most likely to threaten food security by midcentury by reducing the availability of fish and shellfish.

At the top of the list is tiny Comoros, an island nation off the coast of Madagascar, followed by the West African country of Togo and the Cook Islands, dots in the South Pacific Ocean.

Nations whose fisheries are most at risk from climate change, ocean acidification

1. Comoros
2. Togo
3. Cook Islands
4. Kiribati
5. Eritrea
6. Mozambique
7. Madagascar
8. Pakistan
9. Sierra Leone
10. Thailand

Source: Oceana

"People often wrongly think that climate change stops where the water begins, but the oceans are absorbing most of the heat and the carbon dioxide that we've created, so it's a serious threat to the ocean bread basket," said the report's author, Matt Huelsenbeck, a marine scientist with Oceana's energy and climate group.

Worldwide, 1.5 billion people depend on seafood for at least one-fifth of the animal protein they consume. Demand for fish and shellfish is expected to rise over the next several decades as the planet's population rises.

Previous studies have attempted to determine which nations are most vulnerable to the effects of climate change or ocean acidification, but Huelsenbeck said the new report is the first to rank countries based on their combined risks.

As the ocean warms, many commercial fish stocks are moving poleward in search of cooler waters. And rising ocean temperatures have triggered coral bleaching events that have caused widespread damage to the world's reefs, which serve as a habitat for many species.

Population growth as seafood declines

Three-quarters of the planet's reefs are now threatened by a combination of factors that include overfishing, coastal development, water pollution, climate change and changes in ocean chemistry caused by rising carbon dioxide emissions, according to a report released last year by the World Resources Institute that was compiled by more than 25 science and environment groups.

As man-made emissions of CO2 have increased, oceans have absorbed more and more of the heat-trapping gas. That has left the global oceans 30 percent more acidic than they were before the Industrial Revolution began -- a transformation that has occurred faster than at any time in the past 300 million years, according to research published last year in the journal Science.

The long-term effects of that continuing ocean acidification could be severe. Researchers believe the phenomenon could scramble ocean ecosystems by making it harder for sea creatures like oysters, coral, clams and plankton to grow the hard, chalky shells that protect them from predators. At some point, the shift in ocean chemistry may overwhelm the animals' ability to form any shell at all.

To rank countries' vulnerability to climate change, the new report examined model projections of lost fisheries catch potential in individual countries' exclusive economic zones, data on fish and seafood consumption compiled by the U.N. Food and Agriculture Organization, and U.S. government projections of population growth through 2050 and statistics on per capita gross domestic product.

To rank the nations' vulnerability to ocean acidification, the report relies on model projections of changes in ocean acidification, data on mollusk consumption and coral reef-dependent fisheries, and the same U.S. government population and economic data used in the climate change rankings.

The ultimate ranking combines both types of vulnerability. It finds tiny Comoros most threatened.

"They have very poor adaptation factors, as one of the least-developed nations on this list," Huelsenbeck said. "They already have a very high level of undernourishment, so any potential loss of food sources would be very damaging. And they have a very fast-growing population on a very small island."

Rounding out the top 10 are other small island nations and coastal African states, along with a few surprises. Pakistan is ranked No. 8 on the list, due in part to its long coastline and widespread poverty. Thailand is No. 10.

Least able to adapt hit hardest

But the list does not tell the whole story.

"One of the hardest things that this report can reach to is the regional impacts, which might be much more severe than what this assessment tells you," Huelsenbeck said.

Some islands in the Philippines (ranked 34th) may be more severely affected than the nation as a whole, depending on the level of local dependence on fish protein, he said.

While the United States is not included in the top 50 ranking, that does not mean that its fisheries are not vulnerable to climate change and ocean acidification, the report notes.

"Predicted regional losses in fisheries catch potential along the continental U.S. coasts range from losses of five percent to more than 50 percent in some regions," the analysis says. "If marine species continue to move further offshore into deeper waters and higher latitudes it would significantly raise the costs of catching seafood, and this might put many small-scale fishermen out of business."

Alaska could benefit from fish's poleward migration, the report continues, but the state is especially vulnerable to ocean acidification because cold water holds more carbon dioxide than warm water does.

In the short term, adaptation measures designed to reduce existing stresses on fisheries and reefs -- like overfishing and water pollution -- may help blunt the effects of rising temperatures and changing ocean acidity, the Oceana analysis says.

But in the long term, cutting man-made greenhouse gas emissions "is number one," Huelsenbeck said. "In order to keep conditions stable in the oceans, we need to reduce CO2 emissions."

Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500. E&E Publishing is the leading source for comprehensive, daily coverage of environmental and energy issues. Click here to start a free trial to E&E's information services.

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