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partner project Global Carbon Project (GCP) The international carbon cycle research community is currently coordinating the largest, most comprehensive assessment it has ever undertaken: the Regional Carbon Cycle Assessment and Processes (RECCAP). The objective: to establish the mean carbon balance and change over the period 1990-2009 for all subcontinents and ocean basins. Three key objectives justify the need for such a new assessment of regional carbon fluxes and their drivers: (1) To provide higher spatial resolution for the global carbon balance with the aim of improving quantification and understanding of drivers, processes and hot-spots regions, essential for predicting the future evolution of the carbon-climate feedback; (2) To address a growing demand for a capacity to Measure, Report, and Verify (MRV) the evolution of regional fluxes and the outcomes of climate mitigation policies; and (3) To respond to the Group on Earth Observations (GEO) in establishing a global carbon observing system, as in the GEO Carbon Observation Strategy report (http://www.globalcarbonproject.org/mis c/JournalSummaryGEO.htm). RECCAP’s fundamental tenet is to establish carbon budgets in each region by comparing and reconciling multiple bottom-up estimates, which include observations and model outputs, with the results of regional top-down atmospheric CO2 inversions. The effort is guided by a methodology that includes diverse data with their uncertainties, and a 2-tier system that ensures a common approach and a minimum set of analyses performed by all regions. There are 14 regions in the RECCAP synthesis, including 10 terrestrial (Africa, Arctic tundra, Australia, Europe, Russia, East Asia, South Asia, Southeast Asia, Central and South America, North America) and 4 ocean regions (Atlantic +Arctic, Indian, Pacific, Southern Ocean). In addition, 8 global syntheses will support the integration of the regional carbon budgets into a global picture, and provide the link to the top-down constraints delivered by atmospheric observations and inversion models. RECCAP is an assessment of the Global Carbon Project (GCP) with several sponsors including EU-COCOS, USA- Carbon Cycle Research Program, and Australia-CSIRO. Pep Canadell, Executive Director, Global Carbon Project www.globalcarbonproject.org/reccap Atmospheric CO2 Trends Hinder Detection of Oceanic CO2 Accumulation Nathalie F. Goodkin 1 , Naomi M. Levine 2 , Scott C. Doney 3 , Rik Wanninkhof 4 1University of Hong Kong, Hong Kong SAR China, 2Harvard University, Organismic and Evolutionary Biology, Cambridge, MA USA, 3Woods Hole Oceanographic Institution, Dept. of Marine Chemistry and Geochemistry, Woods Hole, MA USA, 4Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, FL USA Contact: goodkin@hku.hk Nathalie Goodkin received her Ph.D. in Chemical Oceanography from the MIT/WHOI Joint Program before completing a Post Doctoral Fellowship at the Bermuda Institute of Ocean Sciences. She is currently an Assistant Professor in the Environmental Science Program at the University of Hong Kong. The ocean is a critical reservoir in the carbon cycle for mitigating the effects of rising atmospheric CO2. While the oceanic sink is estimated to currently be 25% of annual CO2 emissions (eg. Le Quéré et al. 2009), this is likely to decrease over the next 100 years as ocean temperatures increase and the ocean becomes saturated with CO2. In order to anticipate changes in oceanic uptake, we must improve our understanding of how much anthropogenic CO2 is currently being absorbed by the ocean. Since the 1980s, internationally organised field campaigns such as the World Ocean Circulation Experiment (WOCE) monitored the ocean carbon sink through the collection of column hydrographic data. Many of these surveys are being repeated every 5-10 years through efforts such as the CLIVAR/CO2 repeat hydrography program. MLR Residuals (µmol/kg) 30 20 10 0 A Natural variability, however, makes it hard to discern increases in anthropogenic derived carbon. Therefore, empirical techniques such as the extended Multiple Linear Regression (eMLR) (eg. Friis et al 2005) are commonly used to isolate the anthropogenic carbon signal from natural variability. In our study (Goodkin et al., submitted), we use the Community Climate System Model (CCSM) to better understand the impacts climate and atmospheric CO2 trends may have on estimates of the ocean carbon sink on decadal to centennial time scales in the Southern Ocean (south of 32°S). Specifically, examining the commonly used eMLR technique, we find that secular trends in both CO2 and temperature decrease the reliability of the eMLR technique. -10 2030 -20 1990 -30 -30 -20 -10 0 10 20 30 1980 MLR Residuals (µmol/kg) Figure 1 : DIC residuals (µmol/kg) across the Southern Ocean from the MLR for 1990 (blue) and 2030 (green) versus 1980 MLR residuals. Residuals are calculated for each decade by subtracting model DIC from MLR predicted DIC using model output of temperature, salinity, oxygen, phosphate, and alkalinity. //18 surface ocean - lower atmosphere study
Error as a percent of Canthro 40 35 30 25 20 15 10 5 0 B 0 20 40 60 80 100 Decade Intervals for eMLR Figure 2 : Error in Canthro estimate in the Southern Ocean induced by secular change. The error is calculated as the root mean squared error and is presented as an absolute percentage of the change in anthropogenic carbon relative to the time elapsed. Error bars are one standard deviation. MLR techniques take advantage of relationships between dissolved inorganic carbon (DIC) and hydrographic properties to filter out natural variability. This technique, however, depends on a linear relationship between DIC and hydrographic properties and stable regression residuals through time (Figure 1). Non-uniform and nonlinear increases in DIC due to variable anthropogenic carbon uptake and longterm trends in the physical and biological Conference Calendar state of the ocean result in an increasingly non-linear relationship between DIC and hydrographic properties with time. Ultimately, as the time interval increases, the regression residuals no longer cancel and our predictive ability decreases. After a period of 40 years, the residuals are no longer significantly correlated and the error in predicted anthropogenic carbon has increased to greater than 20% (Figure 2). These results are a conservative estimate due to low-climate sensitivity of the CCSM model and as the analysis was conducted using decadal means that average subdecadal scale variability. Therefore, we believe that significant errors could occur on much shorter time scales and that repeat observations are needed on the order of decades to avoid the impact of secular change on the empirical estimates of anthropogenic CO2. As we approach the 30th anniversary of WOCE, the oceanographic community recognises the importance of extensive field measurements in order to closely monitor the role the ocean will play in absorbing CO2. For instance, the GO-SHIP effort (www.go-ship.org) co-sponsored by <strong>SOLAS</strong> is an international effort towards a sustained global survey of the ocean interior. References: Le Quéré, C., Raupach, M.R., et al. (2009). Trends in sources and sinks of carbon dioxide, Nat. Geoscii. 2: 831-836. Friis, K., Körtzinger, A., et al. (2005). On the temporal increase of anthropogenic CO2 in the subpolar North Atlantic. Deep-Sea Res. I. 52:681-698. Goodkin, N.F., Levine, N.M., et al. (submitted). Impacts of Temporal CO2 and Climate Trends on the Detection of Ocean Anthropogenic CO2 Accumulation. Month Dates Conference Location February 13 - 18 American Society of Limnology and Oceanography (ASLO) Aquatic Sciences Meeting Puerto Rico March 22 - 23 SOPRAN Annual Meeting Heidelberg, Germany April 03 - 04 The Workshop of Climate Change and Ocean Carbon - Field Observation, Remote Sensing and Modeling (a joint workshop of OCCOS and CHOICE-C) Xiamen, China April 03 - 08 European Geosciences Union General Assembly 2011 Vienna, Austria May 02 - 04 11th Conference on Polar Meteorology and Oceanography Boston, Massachusetts May 02 - 06 43rd International Liege Colloquium on Ocean Dynamics Tracers of physical and biogeochemical processes, past changes and ongoing anthropogenic impacts Liege, Belgium May 22 - 26 IUPAC International Congress on Analytical Sciences 2011 Kyoto, Japan May 23 - 26 Ecosystem Studies of Sub-Arctic Seas (ESSAS) Open Science Meeting Seattle, Washington, USA June 14 - 18 22nd Pacific Science Conference "Meeting the Challenges of Global Change" Kuala Lumpur, Malaysia June 20 - 24 Seventh EGU Alexander von Humboldt International Conference on Ocean acidification: consequences for marine ecosystems and society Penang, Malaysia For more information on forthcoming meetings and events please visit http://www.solas-int.org/news/conferencemeetings/conference.html www.solas-int.org //19
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