The effect of CO₂ enrichment in raising the temperature was realized in the Open Top Chamber (OTC) experiment. The elevated CO₂ with this level of temperature raised grain yield and yield components of rice but varied greatly by year. The CO₂ enriched plot had lesser N, P, and K in grain, straw, and root but higher organic carbon (OC) in the root compared to the Ambient and the Field. The study indicated that this rise of temperature due to the elevated CO₂ could not adversely affect the yield.

In P. maximum the cumulative dry biomass production in two cuttings showed an increase of 59.24% and 43.17% in open top chambers (OTC) with elevated CO₂ (600±50 ppm) (C₆₀₀) and without elevated CO₂ (C_OTC) respectively over the open field grown corps (Ca). In S. hamata the dry matter increased by 39.79% under C₆₀₀ and 31.02% in C_OTC over Ca. The canopy photosynthesis (P_N x LAI) increased significantly in both the crop species with elevated CO_2. The increased rate of canopy photosynthesis indicated that there was higher assimilation of CO₂, which has intern maximum biomass production. The increase in fresh and dry matter accumulation in C₆₀₀ indicating that these crop species should be promoted for higher biomass production and carbon sequestration in the semi arid tropical environmental conditions.

The effect of three atmospheric CO₂ concentrations (ambient – 400 ppm, doubled – 800 ppm and tripled – 1200 ppm) has been studied (1) on the productivity of cottonwood tree (Populus deltoides Barr.), (2) on the activity of soil microbial biomass in rooting zone. It has been shown, that the total biomass of cottonwood trees increase under elevated CO₂ (2.61, 5.59 and 4 kg/tree for 400, 800 and 1200 ppm respectively). The highest production had the stem and coarse roots at 800 ppm (in 3 and 2 times higher as compared to ambient CO₂). Under 1200 ppm CO₂ we observed increased the roots biomass, but the biomass of leaves and branches was insignificant or didn’t changed at all. The shoot/root ratio changed as following: 400 ppm – 1.8, 800 ppm – 2.3, 1200 ppm – 1.4. The rate of С-СО₂ flux from soil samples being incubated for 70 days increased in the row 1200>800>400 ppm CO₂, the average values of CO₂ emission were 2.76, 2.33, 2.02 mg 100g^-1·day^-1, respectively. The largest amount of C microbial biomass (C_mb) was in the variant with triple CO₂ concentration (75.1 mg 100g^-1), and the lowest – under ambient concentration (53.7 mg 100g^-1).

Coral reefs are constructed of calcium carbonate (CaCO₃). Deposition of CaCO₃ (calcification) by corals and other reef organisms is controlled by the saturation state of CaCO₃ in seawater (Ω) and sea surface temperature (SST). Previous studies have neglected the effects of ocean warming in predicting future coral reef calcification rates.  In this study we take into account both these effects by combining empirical relationships between coral calcification rate and Ω and SST with output from a climate model to predict changes in coral reef calcification rates.  Our analysis suggests that annual average coral reef calcification rate will increase with future ocean warming and eventually exceed pre-industrial rates by about 35% by 2100. There is evidence however to suggest that different corals display different sensitivities to changes in Ω_arag and SST [Reynaud et al., 2003].  Considering that both these environmental parameters are likely to change considerably in the future, additional experiments on a variety of differing coral species will be crucial to obtain a better understanding of future coral reef stability.

Anthropogenic CO₂ uptake by the ocean will decrease both the pH and the aragonite saturation state (Ω_arag) of seawater. However, the factors controlling future changes in pH and Ω_arag are independent and will respond differently to oceanic climate change feedbacks such as ocean warming, circulation and biological changes. We examine the sensitivity of these CO₂-related parameters to climate change feedbacks within a coupled atmosphere-ocean model. Although surface pH is projected to decrease relatively uniformly by ~0.25 by the year 2100, we find pH to be insensitive to climate change feedbacks, whereas Ω_arag is buffered by ~15%. The independent climate change response between pH and Ω_arag is attributed solely to the opposing effects associated with ocean warming, which increases Ω_arag but lowers pH. Our result implies that future climate change projections for surface ocean pH can be adequately simulated using ocean-only models, however for Ω_arag more complex coupled atmosphere-ocean models are required.

Increasing atmospheric CO₂ concentrations lowers oceanic pH and carbonate ion concentrations, thereby decreasing the level of saturation of calcium carbonate [Feely et al., 2004]. This acidification will eventually lead to undersaturation and dissolution of calcium carbonate in parts of the surface ocean. Besides affecting the global carbon cycle, these changes threaten marine organisms that form their exoskeletons out of CaCO₃, which are essential components of the marine food web [Orr et al., 2005]. We investigate magnitude and pattern of ocean acidification due to increasing atmospheric CO₂ concentrations and global warming, both for the recent past and the near future, using the reduced complexity, Bern 2.5-D physical-biogeochemical climate model and a series of CO₂ emission scenarios and CO₂ stabilization profiles provided by the Intergovernmental Panel on Climate Change (IPCC). The focus of the study is on the impact of global warming and induced ocean circulation changes on the projected oceanic pH and carbonate ion reductions.

We applied the Bayesian probability inversion and a Markov Chain Monte Carlo (MCMC) technique to a terrestrial ecosystem model and analyzed uncertainties of estimated carbon transfer coefficients and simulated carbon pool sizes. The study used six data sets of soil respiration, woody biomass, foliage biomass, litterfall, carbon content in the litter layers, carbon content in mineral soil measured under both ambient CO₂ (350 ppm) and elevated CO₂ (550 ppm) plots from 1996 to 2000 at the Duke Forest Free-Air CO₂ Experiment (FACE) site.