Yves here. We first wrote about the dangers of global-warming-induced ocean acidification in 2007, with the key parts from a post by Stormy at Angry Bear:
Global warming skeptics often praise the benefits of global warming. After all, the opening of the Northwest Passage means better trade routes. CO2 in the atmosphere means healthier plants. And who in northern latitudes would not wish for balmier days?
But there are side effects to our love affair with CO2 that are not often mentioned. In fact, whether the earth cools or warms is absolutely irrelevant to these effects. I repeat: Absolutely irrelevant.
One of the most startling effects is the acidification of the oceans. Since 1750, the oceans have become increasingly acidic. In the oceans, CO2 forms carbonic acid, a serious threat to the base of the food chain, especially on shellfish of all sizes. Carbonic acid dissolves calcium carbonate, an essential component of any life form with an exoskeleton. In short, all life forms with an exoskeleton are threatened: shell fish, an important part of the food chain for many fish; coral reefs, the habitat of many species of fish….
The formation of carbonic acid does not depend upon temperature. Whether the oceans warm or cool is irrelevant. Of concern only is the amount of CO2 that enters the oceans. And, as readers of my last thread might remember, we are accelerating our creation of CO2 at an alarming rate…
According to one estimate, between 1750 and 1994, oceans absorbed 118 billion tons of CO2—and we were just starting serious CO2 production. As anyone with a fish tank knows, as the Ph falls, the water becomes more acidic. Fish life becomes more and more problematical.
This absorption has made the world’s oceans significantly more acidic since the beginning of the industrial revolution. Research published last year by Mark Jacobson, an assistant professor of civil and environmental engineering at Stanford University, indicated that between 1751 and 2004 surface ocean pH dropped from approximately 8.25 to 8.14. James Orr of the Climate and Environmental Sciences Laboratory further estimated that ocean pH levels could fall another 0.3 – 0.4 units by 2100.
In fact, by 2050,
…there may be too little carbonate for [in the Pacific] organisms to form shells as soon as 2050.
Since 1990 alone, Ph levels in the Pacific have dropped .0025. Such a drop may not seem significant until one understands Ph levels.
By Andrea Thompson, a senior science writer at Climate Central. Originally published at Climate Central
Hot spots of ocean acidification have been found in the waters that wash onto the shores of the West Coast, a major concern for the region’s billion-dollar fishing industry as well as the region’s potentially fragile coastal ecosystems.
A new study of a 600-mile span of coastline found some of the lowest pH levels ever measured on the ocean surface, showing that significant acidification can be found in waters right along the shore.
One of the sensors used to monitor levels of ocean acidification along the Oregon coast. Oregon State University
“Ocean acidification has made landfall” across the entire area, coauthor Francis Chan, an Oregon State University marine ecologist, said.
But the news from the study, detailed May 31 in the journal Scientific Reports, isn’t all bad: Some areas had more moderate pH levels, and both these and the hot spots persisted in the same areas from year to year. This could give researchers and officials looking to protect marine life a map of where to concentrate efforts to mitigate against rising ocean carbon dioxide levels.
Ocean acidification is the often-overlooked partner to global warming and is driven by the same human-caused emission of carbon dioxide that is driving the rapid rise of global temperatures. The ocean absorbs much of that excess carbon dioxide, and as it does so, the pH of the ocean water declines, meaning it becomes more acidic (just as CO2-laden soda is more acidic than regular water).
As the ocean acidifies, it becomes difficult for shelled organisms such as oysters and clams to build their shells, as well as for fish to breathe. Some of the species that could be most impacted, particularly phytoplankton, sit at the base of the ocean food chain, potentially taking away a key food source for many other species, including some that are most economically valuable, such as salmon and black cod.
The waters off the West Coast of the U.S. are particularly vulnerable to acidification because they feature cold water upwelling from deeper in the ocean. Cold water is better at absorbing CO2 (which also makes acidification in the frigid waters of the Arctic a major concern for marine life there). The cold, upwelling waters also provide abundant nutrients and make the area a rich spot for marine life.
Offshore acidification had been studied before, but with the new study, “we literally took that picture and we moved it all the way to the surf zone,” Chan said.
Multiple institutions joined to install sensors in the coastal waters from Monterey Bay to just north of Newport, Oregon. The sensors monitored conditions for the three years, from 2011 to 2013, and found clear evidence of intense acidification.
Waters fell well below the global average ocean pH of 8.1, with the worst-hit areas measuring 7.4, among the lowest values ever recorded in surface waters.
“The bad news is that we have acidified, compromised water,” Chan said.
But, crucially, “it’s not the same everywhere,” he said. The sensors showed distinct spatial patterns of hot spots and areas where levels were more moderate, and, particularly striking, those areas stayed as hot spots, or relative refuges, “year after year after year.”
Why certain areas have been hit hard and others haven’t wasn’t a focus of the study, but Chan said it likely has to do with the interactions of winds and ocean currents. Some of the sensors from the study are still in place, and Chan is working with citizen scientists in marine reserves in Oregon to better understand local conditions.
He thinks that this same persistent pattern of hot spots and refuges probably isn’t confined to the West Coast. “I think that that’s something that’s going to hold for everywhere in the world,” he said.
Such detailed information is useful for local officials trying to mitigate the impacts of ocean acidification. They can use the maps generated to see where local stressors, such as pollution, might be making conditions worse. They can target the worst-hit areas, while working to ensure that the relative refuges stay that way. Strategies could include limiting local pollution and maintaining healthy kelp beds and sea grasses, which are thought to help mitigate the impacts of acidification.
As atmospheric carbon dioxide levels have risen (in red), the ocean has absorbed some of that CO2 (in green), lowering its pH (in blue). NOAA
Chan was part of a panel of scientists convened by California, Oregon, Washington, and British Columbia to look at the issue of ocean acidification along the West Coast and whether any mitigation could be done on the local and regional level.
Since the April 2016 release of the panel’s report, two bills have already passed in California to reduce the impacts of ocean acidification and promote its research. A bill to establish an ocean policy council is currently moving its way through Oregon’s government.
The Pacific Northwest has been one of the most proactive regions of the U.S. in dealing with ocean acidification, in part because of an oyster hatchery crisis a decade ago. One hatchery saw an 80 percent decline in oysters because of acidic waters. In response, the industry and regional governments implemented an early warning system so that hatcheries can take measures like treating water to prevent damage to their oysters.
Chan has spoken with oyster farmers in Washington about how they might use the coastal acidification maps his work has generated and what they would do if the area they grow oysters in turned out to be a hot spot. Oysters, like wine, have a specific terroir, or flavor, based on where they’re grown, which would seem to make oyster growers reluctant to relinquish their favored spots.
But their response surprised Chan. They said they’d move.