Comparison of the major processes that need to be considered in modeling the carbonate systems in (A) a shallow benthis system (<100 m depth) and (B) an open ocean system (up to 6,000 m in depth). These are oversimpified representations. For example, the dissolution component in both systems involves complicated processes that include differences in mineralogies, organic matter respiration, etc. (compiled by J. Kleypas, 2006).
Priority 2: Investigating the Interactions of the Atmosphere, the Broader Earth System and Human Society
Impacts of Ocean Acidification on Coral Reefs
Background
Carbon dioxide (CO2) is an important trace gas in the atmosphere because of its role in photosynthesis, respiration, ocean chemistry, and global warming. Approximately one third to one half of the CO2 released by human activity has been absorbed by the oceans. This removal of CO2 slows down the rate of global warming, however, it changes seawater chemistry and those changes may have significant impacts on the ocean ecosystem. A number of marine organisms use carbonate (CaCO3 or MgCO3) as a part of their skeletal structure, such as corals, shellfish, and certain microscopic plants and animals. When CO2 is absorbed in seawater, pH decreases (in a general sense, this is referred to as ocean acidification) and the availability of carbonate is reduced. The actual impact on these organisms is uncertain; however, it is believed that these processes play an important role in the global carbon cycle so it is important to understand both the processes and the impacts. The major goal of the collective research on ocean acidification at NCAR, through both specific research and coordination of others' efforts, is to better understand how marine life will respond to continued absorption of CO2 by the ocean, both at the organism and ecosystem levels.
Progress
NCAR scientists collaborated on production of a report that summarizes existing knowledge about ocean acidification and its impacts on marine organisms. The report is the outcome of a workshop held in April, 2005. It also addresses areas for future research and was written as a guide for program managers and researchers to assist in designing future research projects. In addition, the report provides guidance on efficiently coordinating research and monitoring including prioritizing needs, recommending partnerships, and capitalizing on existing efforts. It has generated considerable interest by the federal government with various senators and representatives requesting additional information and briefings to congressional committees.
Plans
Basic field work to conduct carbonate system monitoring on coral reefs began two years ago by NCAR scientists and will continue in coordination with NOAA's Coral Reef Monitoring Network. In addition, ongoing studies will focus on linking marine ecosystem and food web models with NCAR's modeling tools such as the Community Climate System Model (CCSM). Future work on how ocean acidification will affect marine communities will also draw from ongoing ocean carbon cycle modeling efforts at NCAR.
For further detail, please read the full project report linked below.