DOI: 10.1126/science.1155676 , 1490 (2008); 320Science et al.Richard A. Feely,Water onto the Continental ShelfEvidence for Upwelling of Corrosive "Acidified"This copy is for your personal, non-commercial use only.. clicking herecolleagues, clients, or customers by , you can order high-quality copies for yourIf you wish to distribute this article to others. herefollowing the guidelines can be obtained byPermission to republish or repurpose articles or portions of articles (this information is current as of April 29, 2010 ):The following resources related to this article are available online at www.sciencemag.org http://www.sciencemag.org/cgi/content/full/320/5882/1490version of this article at: including high-resolution figures, can be found in the onlineUpdated information and services, http://www.sciencemag.org/cgi/content/full/1155676/DC1 can be found at: Supporting Online Material http://www.sciencemag.org/cgi/content/full/320/5882/1490#otherarticles, 3 of which can be accessed for free: cites 25 articlesThis article 49 article(s) on the ISI Web of Science. cited byThis article has been http://www.sciencemag.org/cgi/content/full/320/5882/1490#otherarticles 5 articles hosted by HighWire Press; see: cited byThis article has been http://www.sciencemag.org/cgi/collection/oceansOceanography : subject collectionsThis article appears in the following registered trademark of AAAS. is aScience2008 by the American Association for the Advancement of Science; all rights reserved. The title CopyrightAmerican Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by theScience on April 29, 2010 www.sciencemag.orgDownloaded fromEvidence for Upwelling of Corrosive“Acidified” Water onto theContinental ShelfRichard A. Feely,1*Christopher L. Sabine,1J. Martin Hernandez-Ayon,2Debby Ianson,3Burke Hales4The absorption of atmospheric carbon dioxide (CO2) into the ocean lowers the pH of the waters.This so-called ocean acidification could have important consequences for marine ecosystems. Tobetter understand the extent of this ocean acidification in coastal waters, we conductedhydrographic surveys along the continental shelf of western North America from central Canadato northern Mexico. We observed seawater that is undersaturated with respect to aragoniteupwelling onto large portions of the continental shelf, reaching depths of ~40 to 120 meters alongmost transect lines and all the way to the surface on one transect off northern California. Althoughseasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in thisregion, the ocean uptake of anthropogenic CO2has increased the areal extent of the affected area.Over the past 250 years, the release ofcarbon d ioxide ( CO2) from industrial andagricultural activities has resulted in atmo-spheric CO2concentrations that have increased byabout 100 parts per million (ppm). The atmo-spheric concentration of CO2is now higher thanit has been for at least the past 650,000 years, andis expected to continue to rise at an increasingrate, leading to pronounced changes in our cli-mate by the end of this century (1). Since thebeg in ni ng of the in du st ri a l era, the oceans haveabsorbed ~127 ± 18 billion metric tons of carbonas CO2from the atmosphere, or about one-thirdof the anthropogenic carbon emissions released(2). This process of absorption of anthropogenicCO2has benefited humankind by substantiallyreducing the greenhouse gas concentrations inthe atmosphere and minimizing some of the im-pacts of global warming. However , the ocean’sdaily uptake of 22 million metric tons of CO2hasa sizable impact on its chem i s t r y and bio l o gy.Recent hydrogra phic surveys and modeling studieshave confirmed that the uptake of anthropogenicCO2by the oceans has resulted in a lowering ofseawater pH by about 0.1 since the beginning ofthe industrial revolution (3–7). In the comingdecades, this phenomenon, called “ocean acidi-fication,” could affect some of the most funda-mental biological and geochemical processes ofthe sea and seriously alter the fundamental struc-ture of pelagic and benthic ecosystems (8).Estimates of future atmospheric and oceanicCO2concentrations, based on the IntergovernmentalPanel on Climate Change (IPCC) CO2emissionscenarios and general circulation models, indicatethat atmospheric CO2concentration s could exceed500 ppm by the middle of this century , and 800ppm near the end of the century . This increase wouldresult in a decrease in surface-wate r pH of ~ 0.4 bythe end of the century , and a corresponding 50%decrease in carbonate ion concentration (5, 9). Suchrapid changes are likely to negatively affect marineecosystems, seriously jeopardizing the multifacetedeconomies that currently depend on them (10).The reaction of CO2with seawater reducesthe availability of carbonate ions that are neces-sary for calcium carbonate (CaCO3)skeletonandshell formation for marine organisms such ascorals, marine plankton, and shellfish. The extentto which the organisms are affected dependslargelyontheCaCO3saturation state (W), whichis the product of the concentrations of Ca2+andCO32−divided b y the apparent stoichiometricsolubility product for either aragonite or calcite:Warag=[Ca2+][CO32−]/K′sparag(1)Wcal= [Ca2+][CO32−]/K′spcal(2)where the calcium concentration is estimatedfrom the salinity, and the carbonate ion con-1Pacific Marine Environmental Laboratory/National Oceanic andAtmospheric Administration, 7600 Sand Point Way NE, Seattle,WA 98115–6349, USA.2Instituto de Investigaciones Oceano-logicas, Universidad Autonoma de Baja California, Km. 103 Carr.Tijuana-Ensenada, Ensenada, Baja California, Mexico.3Fisheriesand Oceans Canada, Institute of Ocean Science, Post Office Box6000, Sidney, BC V8L 4B2, Canada.4College of Oceanic andAtmospheric Sciences, Oregon State University, 104 OceanAdministration Building, Corvallis, OR 97331–5503, USA.*To whom correspondence should be addressed. E-mail:[email protected]°W 130°W 126°W 122°W 118°W 114°WLongitude52°N50°N48°N46°N44°N42°N40°N38°N36°N34°N32°N30°N28°N26°N1234567891011121320406080100120140160180200220240260Depth (m)LatitudeFig. 1. Distribution of the depths of the undersaturated water (aragonite saturation < 1.0; pH < 7.75) onthe continental shelf of western North America from Queen Charlotte Sound,