Ocean acidification is likely to impact calcification rates in many pelagic organisms, which may in turn cause significant changes in marine ecosystem structure. We examine effects of changes in marine CaCO3 production on total alkalinity (TA) in the ocean using the global biogeochemical ocean model HAMOCC. We test a variety of future calcification scenarios because experimental studies with different organisms have revealed a wide range of calcification sensitivities to CaCO3 saturation state. The model integrations start at a preindustrial steady state in the year 1800 and run until the year 2300 forced with anthropogenic CO2 emissions. Calculated trends in TA are evaluated taking into account the natural variability in ocean carbonate chemistry, as derived from repeat hydrographic transects. We conclude that the data currently available does not allow discerning significant trends in TA due to changes in pelagic calcification caused by ocean acidification. Given different calcification scenarios, our model calculations indicate that the TA increase over time will start being detectable by the year 2040, increasing by 5–30 μmol kg−1 compared to the present-day values. In a scenario of extreme reductions in calcification, large TA changes relative to preindustrial conditions would have occurred at present, which we consider very unlikely. However, the time interval of reliable TA observations is too short to disregard this scenario. The largest increase in surface ocean TA is predicted for the tropical and subtropical regions. In order to monitor and quantify possible early signs of acidification effects, we suggest to specifically target those regions during future ocean chemistry surveys.
Archive for February 21st, 2009
The Journal of Marine Education Volume 25, Number 1, 2009 special issue “Ocean Acidification-from Ecological Impacts to Policy Opportunities”
The Threat of Acidification to Ocean Ecosystems
By John Guinotte and Victoria J. Fabry
Researcher Spotlight: Gretchen Hofmann, Ecological Physiologist
By Sandra Brooke
Champagne Seas—Foretelling the Ocean’s Future?
By Jason Hall-Spencer and Elizabeth Rauer
Developing New Instrumentation for in situ Experimentation Related to Ocean Acidification— Scaling up pH Effects from the Lab to the Field
By William Kirkwood and Larissa Sano
Anticipating Ocean Acidification’s Economic Consequences on Commercial Fisheries
By Sarah R. Cooley and Scott C. Doney
The Big Seven: Acidification Risks and Opportunities for the Seafood Industry
By Brad Warren
A Global Perspective on the Economics of Ocean Acidification
By Hauke L. Kite-Powell
What Can Be Done to Address Ocean Acidification Through U.S. Policy and Governance?
By Edward L. Miles and James Bradbury
Resilient Coral Reef Ecosystems Provide a Glimmer of Hope for the Future
By Jennifer Smith, Elizabeth Rauer, and Larissa Sano
Activity: Deepwater Coral Expedition: Reefs, Rigs, and Wrecks
Dear OCB Colleagues.
As you may (or may not) have heard, the Plymouth Marine Laboratory and the Center for Microbial Oceanography: Research and Education (C-MORE), a NSF Science and Technology Center located at the University of Hawaii, have organized a 3-day workshop that includes a science symposium on the topic of “Rising CO2, ocean acidification and their impacts on marine microbes.” The meeting will take place from 24-26 Feb 2009, at the East West Center on the University of Hawaii’s Manoa campus. Funding for the workshop and symposium is provided by the Gordon and Betty Moore Foundation, the Agouron Institute, and the National Science Foundation. A website has been set up to provide additional information about the objectives and format of the workshop, including a flyer advertising the symposium on 24 Feb and abstracts of the presentations that will be made. Please have a look (http://cmore.soest.hawaii.edu/oceanacidification/index.htm) and bookmark this website for future posting of the report of our proceedings.
Aloha, Ian Joint, Dave Karl and Scott Doney