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Ocean Acidification

Ocean acidification is the name given to the ongoing decrease in the pH of the Earth's oceans. What is ocean acidification? What is causing it?

The oceans absorbs abot 33% of the CO2 emitted to the atmosphere from the burning of fuels. This valuable service comes at a steep ecological cost - the acidification of the ocean. As CO2 dissolves in seawater, the pH of the water decreases, which is called "acidification". Read more at http://www.ocean-acidification.net/

The impending catastrophe of ocean acidification

The Natural Resource Defense Council’s documentary ‘Acid Test’ explores the dangers of rising ocean acidity.
By Stephanie Rogers
Mon, Jun 08 2009 at 12:51 PM EST

It’s officially World Oceans Day, an opportunity to explore the importance of our oceans and their rich diversity of life. It’s also a chance to highlight what Daniel Hinerfeld of the Natural Resources Defense Council (NRDC) calls "the scariest environmental problem you’ve never heard of".
 
Hinerfeld is the writer, co-director and executive producer of "Acid Test: The Challenge of Ocean Acidification", a documentary narrated by Sigourney Weaver. He says that although he has worked at NRDC for six years, he knew virtually nothing about ocean acidification before starting work on the film -- and he’s betting that a lot of you haven’t heard of it, either.
Read more

The findings of the study on ocean acidification and its impact on oysters is published in the open access journal PLoS One. (Public Library of Science)

The world's oceans - getting warmer and more acidic

The world's oceans are warming and becoming more acidic. 80% of the heat from human activity has ended up in the ocean. The acidification has been happening since the industrial revolution started in the 1850s. Even if we stop emitting CO2 today, there's a total doubling of hydrogen ions backlogged in the atmosphere and built into the system.

The effects will be dire for animals which build shells if the acidity of the ocean increases. Pterapods are small snails and in the lab it has been shown they won't be able to survive in a more acidic ocean. They play an important part of the marine food web. Tony Haymet says we're running a large irreversible experiment with unknown consequences. Full Story at The Science Show

Dissolving CO2 in seawater also increases the hydrogen ion (H+) concentration in the ocean, and thus decreases ocean pH. Caldeira and Wickett (2003) placed the rate and magnitude of modern ocean acidification changes in the context of probable historical changes during the last 300 million years.

Since the industrial revolution began, it is estimated that surface ocean pH has dropped by slightly less than 0.1 units (on the logarithmic scale of pH; approximately a 25% increase in H+), and it is estimated that it will drop by a further 0.3 - 0.5 units by 2100 as the ocean absorbs more anthropogenic CO2. These changes are predicted to continue rapidly as the oceans take up more anthropogenic CO2 from the atmosphere, the degree of change to ocean chemistry, for example ocean pH, will depend on the mitigation or emissions pathway society takes. Note that, although the ocean is acidifying, its pH is still greater than 7 (that of neutral water), so the ocean could also be described as becoming less basic.

Although the largest changes are expected in the future, a report from NOAA scientists found large quantities of water undersaturated in aragonite are already upwelling close to the Pacific continental shelf area of North America. Continental shelves play an important role in marine ecosystems since most marine organisms live or are spawned there, and though the study only dealt with the area from Vancouver to northern California, the authors suggest that other shelf areas may be experiencing similar effects. Similarly, one of the first detailed datasets examining temporal variations in pH at a temperate coastal location found that acidification was occurring at a rate much higher than that previously predicted, with consequences for near-shore benthic ecosystems. Source Wikipedia

The Acid Ocean – the Other Problem with CO2 Emission

2 July 2005

The Royal Society has just issued a summary report on the effects of CO2 on the pH chemistry of seawater and aquatic organisms and ecosystems. In addition to its pivotal role in the atmosphere in the regulation of global climate, CO2 and its sister chemical species, HCO3- and CO32- comprise the carbonate buffer system which regulates the pH of seawater. The new report can be found here. Acidifying the ocean is particularly detrimental to organisms that secrete shell material made of CaCO3, such as coral reefs and a type of phytoplankton called coccolithophorids [Kleypas et al., 1999]. The ocean pH change will persist for thousands of years. Because the fossil fuel CO2 rise is faster than natural CO2 increases in the past, the ocean will be acidified to a much greater extent than has occurred naturally in at least the past 800,000 years [Caldeira and Wicket, 2003]. Source; http://www.realclimate.org/index.php?p=169