Human carbon emissions make oceans corrosive: study

Human carbon emissions make oceans corrosive: study

Reuters

WASHINGTON (Reuters) - Carbon dioxide spewed by human activities has made ocean water so acidic that it is eating away at the shells and skeletons of starfish, coral, clams and other sea creatures, scientists said on Thursday.

Marine researchers knew that ocean acidification, as it's called, was occurring in deep water far from land. What they called "truly astonishing" was the appearance of this damaging phenomenon on the Pacific North American continental shelf, stretching from Mexico to Canada.

"This means that ocean acidification may be seriously impacting our marine life on our continental shelf right now, today," said Richard Feely of the Pacific Marine Environmental Laboratory, part of the U.S. National Oceanic and Atmospheric Administration.

Other continental shelf regions around the world are likely to face the same fate, he said.

Plenty of natural activities, including human breath, send the greenhouse gas carbon dioxide into the atmosphere, but for the last 200 years or so, industrial processes that involve the burning of fossil fuels such as coal and petroleum have pushed emissions higher.

Oceans have long been repositories for the carbon dioxide, absorbing some 525 billion tonnes of the climate-warming substance over the last two centuries -- about one-third of all human-generated carbon dioxide for that period.

But the daily absorption of 22 million tonnes of the stuff has changed the chemistry and biology of the oceans, turning it corrosive and making it difficult or impossible for some animals to produce their calcium carbonate shells and skeletons, the researchers said.

CHURNING OCEAN WATERS

This change has been observed over the last three decades, the scientists said in research published in the journal Science.

The acidic waters are coming up onto the continental shelf -- the shallow area near a big land mass like North America -- because of a long-term churning ocean pattern that moves cold deep water up toward the surface in the spring and summer, the scientists said.

The carbon-loaded waters that are now near the U.S. West Coast took about 50 years to get there, starting somewhere on the ocean surface and absorbing their share of carbon dioxide, then sinking deep down and eventually welling upward.

The natural process called ocean respiration could not explain the high levels of carbon dioxide that caused the corrosive water the scientists found on the continental shelf; the addition of human-generated carbon dioxide did.

This acidic water is corroding the shells of clams, mussels, starfish and the free-floating sea-snails called pterapods that nourish young salmon, the researchers said, citing data from a 2007 research cruise.

Corrosion occurred in water that absorbed carbon dioxide from the atmosphere in 1957, when levels of this gas were considerably lower than they are now, the researchers said.

"This means that even if we were to stop instantaneously the current rate of rise of carbon dioxide in the atmosphere, the corrosivity of these upwelling waters would increase for the next 50 years," said Burke Hales, a professor of chemical oceanography at Oregon State University.

(Editing by Will Dunham and Philip Barbara)

© Thomson Reuters 2008.

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Everglades Park Counts the Good and the Bad After a Blaze

The New York Times

Friday 23 May 2008

REDLAND, Fla. — Rick Anderson, the fire management officer for Everglades National Park, stood in the burnt grass where the largest fire in 19 years began here last week and assessed the costs and benefits.

The fire, which was 70 percent under control on Thursday, has scorched about 40,000 acres, sent smoke over Miami and forced schools to close temporarily. And yet, it has also poured nutrients into the soil, killed nonnative plants and made it harder for hawks to prey on the endangered Cape Sable seaside sparrow.

Park officials said someone sparked the fire accidentally or by arson, but is the impact good or bad?

“Like so much here, it’s not just one thing,” said Mr. Anderson, who starts planned fires in addition to fighting those that are unwanted. He added, “Fire is our grizzly bear or our wolf: it has to be here.” Then he pointed toward a house in the distance. “But it can’t be over there.”

The Everglades has long faced the challenge of balancing humankind versus nature, and the latest fire is no exception. From its start in a beer-bottle strewn area on the park’s eastern edge, near both homes and the seaside sparrow’s habitat, the blaze has exemplified the struggle to revive a fragile ecosystem that abuts one of the nation’s most developed areas.

Many environmentalists here have described the fire as an indictment of the federal Everglades restoration plan, which after eight years has failed to seize enough water from nearby communities to rehydrate the so-called river of grass.

“This is exactly the area of the park where we should be having more water this time of year,” said Alan Farago, executive director of the Everglades Defense Council. “The park’s on fire, Florida Bay is a disaster, and we’re still fighting over getting enough water of the right quality.”

Mr. Anderson warned that more water alone would not have kept the Everglades from burning. With its wispy vegetation, dry season and high winds, “this place is built to burn,” he said. Even in an idealized Everglades, “there would still be fires,” he said.

But several scientists at the park said the perpetual lack of water had made the fire’s impact more severe. Indeed, the blaze burned 100 acres in just its first few hours, before sunrise on the morning of May 14. And from there it took off, racing along at speeds of up to 8 miles an hour, faster than most people can run.

Park officials initially figured the fire could be managed without affecting nearby neighborhoods because the winds were blowing west, into the park’s roughly one million acres. Mr. Anderson even considered allowing some extra acres to burn, as he often does with fires caused by lightning.

“The Everglades dies without fire,” he said, noting that the ash offers some of the only nutrients available. So his first thought was how to make the blaze serve the ecosystem. His second thought was how to keep the fire from the seaside sparrows’ nests.

Then on the afternoon of May 15, the winds shifted north and east, toward a prison on the park’s edge and the outer rings of South Miami-Dade County. Suddenly, the emphasis became people and property.

Miami-Dade firefighters began going door to door to make sure families knew the fire might be coming. Several hundred prisoners were evacuated, and a handful of schools closed temporarily or canceled outside recess because of smoke.

More than 200 firefighters worked up to 16-hour days to fight the blaze. At one point, park officials said they persuaded the South Florida Water Management District and the Army Corps of Engineers to push more water into the park. But it was not enough.

“Even with all the water they let in, it didn’t do much because the water levels were so low,” said David E. Hallac, chief of the biological resources branch. He pointed to a canal nearby that showed dry, crusty earth three feet down.

So eventually, officials turned to fire retardants, dropped near the park’s northeastern corner. It was a break with policy that park officials are hoping did only minimal damage because they were heavily diluted.

And a planned fire from a year ago also seems to have played a role in keeping the latest blaze from spreading to more residential areas. By denying the blaze fresh fuel, it helped firefighters keep the fire on one side of a road near the park’s boundary.

Inside that area on Thursday, scientists in yellow fireproof shirts carried clipboards and cameras to the clusters of trees where the park’s biodiversity is concentrated. Mr. Hallac and his team emerged with evidence of both life and death. The trees had been burned to a dry rust or dark black. Mr. Hallac said he saw a scorched turtle that might have survived had there been a puddle of water for it to hide in.

But a lizard also slid past him and green sprouts of grass could be seen in areas that had been on fire only a few days ago.

As helicopters with firefighters or water passed overhead, the scientists said they were still trying to figure out the mix of positive and negative consequences.

It was unclear how the seaside sparrow fared, and no one could say for sure whether the invasive plants that had been killed by the fire would return. Everglades National Park had once again been altered by man and was in the process of moving on.

“This thing is alive,” Mr. Anderson said of the park. “It’s always changing, and any change from outside kicks it another direction. This environment is dynamic as hell.”

http://www.nytimes.com/2008/05/23/us/23florida.html?_r=1&oref=slogin&partner=rssnyt&emc=rss&pagewanted=print