Results of airborne CO₂ and CO observations from the NSF/NCAR C-130 platform during the Gulf of Tehuantepec Experiment (GOTEX 2004) and the Airborne component of the Carbon in the Mountains Experiment (ACME 2004) will be presented. A modified commercial vacuum ultraviolet fluorescence instrument monitored CO mixing ratios. CO measurements were used to help identify air masses recently influenced by combustion emissions. CO₂ mixing ratios were measured using a pressure- and temperature-controlled LI-COR 6252 analyzer.  Control of time response allowed operation of the CO₂ instrument in two modes for application to either low altitude eddy covariance or higher altitude mixing ratio measurements. Performance will be assessed, including accuracy estimates derived from intercomparison activities.

The CROZEX cruises (November 2004 to January 2005) had the objective to test whether natural iron fertilisation from the Crozet plateau promotes algal blooms. Results from the cruises show that algal blooms created an oceanic CO₂ sink downstream of the Crozet plateau. Vertical advection of water into the mixed layer occurred close to two islands on the plateau. Data from 18 cruises between 1991 and 2002 are used to quantify the seasonal variability of surface pCO₂ and CO₂ air-sea exchange in the region.

We present a synthesis Bayesian inverse method to optimize one year of daily fluxes at model resolution (50x50 km over Europe) by inversion of continuous CO₂ measurements, daily averaged over Europe (10 sites). Based on a synthetic data analysis, we studied the impact of three different spatial and temporal correlations on flux errors. We found that the present network is too sparse to efficiently constrain European fluxes at model resolution even with the assumption of perfect transport. However, the agreement between the optimized fluxes and the true fluxes is improved when aggregated in space and time, mainly for 8-10 days fluxes over Western Europe. This region is indeed surrounded by our network. The spatial correlation scheme used was found to have a negligible impact on this agreement. Adding a white noise on pseudo-data to simulate transport model errors largely degrades the agreement. Using real data, European flux variations becomes unreasonably large due to the inability of our transport model to properly represent the CO₂ concentrations at continental sites.

Changes in dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) in the water column are quantified for meridional hydrographic sections through the Atlantic from 63 ˚N to 60 ˚S between 1988/1993 and 2003/2005.  Changes are most pronounced in the upper 1000 m water column.  DIC changes range from -5 to 40 µmol/kg and AOU changes by a similar amount.  The remainder is caused by changes in positions of fronts, gyres, remineralization and ventilation as manifested by changes in watermass properties.  In particular AOU increases of similar magnitude as increases in DIC point towards a significant contribution of oxidation of organic matter to the DIC increase.  The large changes in biogeochemical properties of the upper water column of the Atlantic have been one of the big surprises in the decadal reoccupation of the transects.

There is growing evidence that the rate of anthropogenic CO₂ uptake in the ocean is changing over time. Several programs are poised to assess current and future ocean CO₂ uptake rates, but there are issues with how to extrapolate these measurements to decadal-scale changes over entire ocean basins. One possibility is to exploit the growing network of ARGO floats that are collecting profiles throughout the global oceans. We explore the viability of this approach and make recommendations for how the ARGO network might be made more useful for biogeochemical applications.

Using high-quality data for the CO₂-system and related properties obtained 10-year apart, we estimated decadal increases of anthropogenic CO₂ along the A10 section of the World Ocean Circulation Experiment (WOCE) Hydrographic Program (WHP). Increases of anthropogenic CO₂ were found down to an isopycnal surface of 27.3σ_θ (approx. 1000 dbar). In the sub-Antarctic Mode Water (SAMW), the increase was 6.9 ± 2.0 μmol kg^-1 on average, while in the Antarctic Intermediate Water (AAIW), it was 4.2 ± 1.9 μmol kg^-1. The increase in SAMW was larger in the west than that in the east of the section. No significant increases were detected in North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW).

The decadal variability of air-sea CO₂ fluxes is poorly known in the southern hemisphere. To evaluate the changes or stability of these fluxes over several years, we compare seasonal observations obtained in 1991 and 2000 the Southern Indian Ocean. For summer and winter, we observed a significant increase of ocean fugacity (fCO₂) in subtropical waters (20°-35°S), about the same rate as in the atmosphere. In polar waters south of 40°S where meso-scale biological activity is high in summer, the rising of oceanic fCO₂ is only well detected when comparing austral winter data. The decadal evolution of fCO₂ observed in the cold waters certainly results from anthropogenic CO₂ emissions, but is also probably modulated by variations of primary production.

The measurement results of CO₂ average concentration obtained in the atmospheric column at the Issyk-Kul station (IK) (42.6⁰N, 77.0⁰E, 1650 m a.s.l.) in 1980-2004. A comparison was made with the MBL data (for the IK latitude) presenting mean zonal CO₂ concentrations reduced to the sea level and with the measurement results of CO₂ concentrations obtained at KZD (44.45⁰N, 77.57⁰E, 412 m a.s.l) and KZM (43.25⁰N, 77.88⁰E, 2519 m) sites. The IK station is about 100 km distant from KZM and 220 km distant from KZD.

The coupled feedback processes of energy and carbon cycles are an essential mechanism for understanding global environmental change. We developed a simplified one-dimensional carbon and energy cycle coupled model to quantify the feedback processes between energy and carbon cycles. The model was calibrated to reproduce the historical variations in temperature and atmospheric CO₂ concentration. The model results of vertical ocean temperature profiles, and latitudinal NPP and NEP distributions were in good agreement with the observation data and terrestrial biosphere model results. The regional difference of terrestrial ecosystem response by climate feedback appeared in the middle and high latitudes. The north-south distribution is important to investigate the terrestrial ecosystem because the opposite response appeared in the middle and high latitude. The future change of carbon cycle and climate was also simulated up to the year 2100 based on the IPCC scenario. The atmospheric CO₂ concentration reaches 735 ppmv in 2100 and global average temperature increases 1.9 K for 2000-2100.