Eye to Eye with Climate Change in the Ocean

Eye to Eye with Climate Change in the Ocean
Published on May 19, 2014
Dr. Kaufman describes the sweeping transformation in the world ocean, brought about by climate change and also by pollution and over-fishing. His examples are global: from the most remote coral atolls of the Pacific nation of Kiribati, to the threatened waterfronts and fisheries of Massachusetts.

Climate change: Pacific Ocean acidity dissolving shells of key species

Climate change: Pacific Ocean acidity dissolving shells of key species

Paul Rogers. 04/30/2014 mercurynews.com

In a troubling new discovery, scientists studying ocean waters off California, Oregon and Washington have found the first evidence that increasing acidity in the ocean is dissolving the shells of a key species of tiny sea creature at the base of the food chain.

The animals, a type of free-floating marine snail known as pteropods, are an important food source for salmon, herring, mackerel and other fish in the Pacific Ocean. Those fish are eaten not only by millions of people every year, but also by a wide variety of other sea creatures, from whales to dolphins to sea lions.

If the trend continues, climate change scientists say, it will imperil the ocean environment.

An unhealthy pterapod whose shell is dissolving due to rising levels of oceanic acidity. (NOAA/Steve Ringman)

"These are alarm bells," said Nina Bednarsek, a scientist with the National Oceanic and Atmospheric Administration in Seattle who helped lead the research. "This study makes us understand that we have made an impact on the ocean environment to the extent where we can actually see the shells dissolving right now."

Scientists from NOAA and Oregon State University found that in waters near the West Coast shoreline, 53 percent of the tiny floating snails had shells that were severely dissolving -- double the estimate from 200 years ago.

Until now, the impact on marine species from increasing ocean acidity because of climate change has been something that was tested in tanks in labs, but which was not considered an immediate concern such as forest fires and droughts.

The new study, published in the Proceedings of the Royal Society B, a scientific journal based in England, changes that.

"The pteropods are like the canary in the coal mine. If this is affecting them, it is affecting everything in the ocean at some level," said one of the nation's top marine biologists, Steve Palumbi, director of Stanford University's Hopkins Marine Station in Pacific Grove.

The vast majority of the world's scientists -- including those at NOAA, NASA, the National Academy of Sciences and the World Meteorological Organization -- say the Earth's temperature is rising because of humans burning fossil fuels like oil and coal. That burning pumps carbon dioxide into the atmosphere and traps heat, similar to a greenhouse. Concentrations of carbon dioxide in the Earth's atmosphere have increased 25 percent since 1960 and are now at the highest levels in at least 800,000 years, according to measurements of air bubbles taken in ancient ice and other methods.

Many of the impacts are already being felt. Since the 1880s, when modern temperature records were first taken, the 10 hottest years have all occurred since 1998. Polar ice has melted, forest fires are burning in the West with increasing frequency, and the ocean has risen 8 inches since 1900 at the Golden Gate Bridge.

But what many people do not realize is that nearly a third of carbon dioxide emitted by humans is dissolved in the oceans. Some of that forms carbonic acid, which makes the ocean more corrosive.

Over the past 200 years, the ocean's acidity has risen by roughly 30 percent. At the present rate, it is on track to rise by 70 percent by 2050 from preindustrial levels.

More acidic water can harm oysters, clams, corals and other species that have calcium carbonate shells. Generally speaking, increasing the acidity by 50 percent from current levels is enough to kill some marine species, tests in labs have shown.

The new research on the marine snails does not show that increasingly acidic water is killing all of them, particularly older snails. But it is causing their shells to dissolve, which can make them more vulnerable to disease, slow their ability to evade predators and reduce their reproductive rates, the researchers said.

Some of the corrosive water near the shore could be a result of other types of pollution, such as runoff from fertilizer and sewage, said Stanford's Palumbi, who was not involved in the NOAA research. But because the study found rates of the snails' shells dissolving in deep water, far from the shore, human-caused carbon dioxide is the prime suspect, he added.

If people reduce emissions of fossil fuels, cutting carbon dioxide levels in the decades ahead, the damage to the oceans can still be limited, he said.

"But if we keep on the emissions profile we have now, by 2100 the oceans will be so harmed it's hard to imagine them coming back from that in anything less than thousands of years," Palumbi said.

"We are in a century of choice," he said. "We can choose the way we want it to go."

Pollution Sours Pacific Ocean More than Expected

Pacific Ocean near Equator. 

Pollution Sours Pacific Ocean More than Expected

The world's largest ocean is absorbing carbon dioxide, and turning more acidic as a result, faster than expected

Stephanie Paige Ogburn, Mar 27, 2014 ClimateWire

The amount of carbon dioxide in the tropical Pacific Ocean has increased surprisingly quickly over the past 14 years, according to new research from scientists at the National Oceanic and Atmospheric Administration and the University of Washington.

The reason for the rapid increase in carbon dioxide concentrations is a combination of natural variability and human-caused emissions of carbon dioxide into the atmosphere, said Adrienne Sutton, a research scientist with NOAA's Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington.

Although it is difficult to tease out exactly how much of the increase in carbon dioxide concentrations is due to human-caused climate change, "we assume that most of the carbon dioxide increase [in the tropical Pacific] is due to anthropogenic CO2," Sutton said.

In fact, the rate of increase in carbon dioxide concentrations in parts of the tropical Pacific Ocean, a band of ocean along the equator between the coasts of South America and Southeast Asia, is greater than the rate of increase of atmospheric carbon dioxide.

Measurements by atmospheric scientists at NOAA show that atmospheric CO2 is increasing at a rate of about 2 parts per million per year. But in parts of the tropical Pacific, the rate of change in CO2 concentrations measured by the researchers reached 3.3 ppm per year.

"It was a big surprise. We were not expecting to see rates that strong," Sutton said.

Current models do not predict such large increases in carbon dioxide concentrations in that part of the ocean, which is one of the reasons those findings were unexpected. The data were collected from a set of seven buoys in the tropical Pacific, starting in 1998.

Because that part of the ocean is dominated by many natural cycles, including the El Niño Southern Oscillation and the Pacific Decadal Oscillation, the researchers had to work to disentangle the overall signal of carbon dioxide concentrations from the variability caused by natural changes.

"One of the reasons why we were really interested in putting these CO2 systems on the buoys was so that we could see the incredible natural variability that occurs in this region," Sutton said.

For the first few years of data collection, the researchers saw a clear signal of carbon dioxide growth rates changing as the ocean switched from El Niño to neutral to La Niña.

Shellfish and coral reefs at risk
Now that they have been collecting data for over 15 years, they have begun to see the effects of longer term cycles, such as that of a 20- to 30-year natural fluctuation called the Pacific Decadal Oscillation, Sutton said.

The scientists are also seeing the effects of climate change, one of which is an increasingly acidic ocean. The carbon dioxide they see in the tropical Pacific now is from water that was last in contact with the atmosphere 10 years ago, Sutton said.

In subtropical regions of the ocean north and south of the equator, the ocean gets into an equilibrium with whatever concentration of carbon dioxide is in the atmosphere at that time -- and every year, that atmospheric concentration has increased due to human emissions of CO2.

Then, the water is pushed deep into the ocean, where it collects more carbon dioxide due to natural biological processes. It eventually upwells back in the tropical Pacific.

"That water is carrying anthropogenic CO2 plus this natural CO2. So when it upwells along the equator, you are seeing both of those processes drive to produce CO2," Sutton said.

In parts of the U.S. coast, ocean acidification has led to negative impacts on the shellfish industry, since it affects the ability of those organisms to build their shells.

In the tropical Pacific, coral reefs have the potential to be affected by increasing concentrations of carbon dioxide and a more acidified ocean, since more acidic oceans have been shown to reduce the ability of reef-building corals to create their skeletons.

Scott Doney, a senior scientist and director of the Woods Hole Oceanographic Institution's Ocean and Climate Change Institute, who was not affiliated with the study, pointed out that "the research demonstrates the importance of continuous ocean observations (e.g., moorings, robots)."

"Only through careful analysis of long-term data sets can we separate the effects of natural climate variability from anthropogenic trends such as climate change and ocean acidification," Doney wrote in an email.

Watching acidification more closely.
As a follow-up to this research, Sutton and her colleagues plan to look at an even longer period of time using observations made not just from buoys but from measurements taken from ocean cruises as well.

The scientists hope to be able to determine more specifically what portion of the carbon dioxide concentration increase is due to human causes, and what portion is due to natural oscillations.

Yesterday, NOAA, the agency behind Sutton's research, also announced a new strategic plan guiding its monitoring and research on ocean acidification.

The plan goals include improving observation systems that monitor ocean acidification, such as the buoy systems used by Sutton and others.

Other goals include conducting laboratory and on-site research on acidification; developing comprehensive models to predict changes to the ocean's carbon cycle; assessing the cultural, subsistence and economic impacts of ocean acidification; and developing a data management plan for what is collected on the topic.

"Scientific study of ocean acidification is young enough that researchers are making surprising major discoveries every year," said Libby Jewett, director of NOAA's Ocean Acidification Program, said in a statement about the strategic plan.

"Federal investment in basic research, long-term monitoring, and multi-disciplinary, applied research, will allow U.S. scientists to develop the knowledge needed to inform policy and help prepare society for rapid shifts in ocean chemistry."