In this paper, we use a coupled climate and carbon cycle model to investigate the global climate and carbon cycle changes out to year 2300 that would occur if CO₂ emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By year 2300, the global climate warms by about 8 K and atmospheric CO₂ reaches 1423 ppmv. In our simulation, the prescribed cumulative emission since pre-industrial period is about 5400 Gt-C by the end of 23^rd century. At year 2300, nearly 45% of cumulative emissions remain in the atmosphere. In our simulations both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, our model projections suggest severe long-term consequences for global climate if all the fossil-fuel carbon is ultimately released to the atmosphere.

We estimated the effects of initial vertical distribution of dissolved inorganic carbon (DIC) on storage efficiency of direct injection of CO₂ into the ocean. Our simulations shown that the storage efficiencies could be reduced up to 10% if a relative large droplet (30 mm in diameter) was injected at depth of 1500m. The storage efficiency of CO₂ ocean sequestration is strongly related with not only injection depth but also the initial CO₂ droplet diameter. With a given injection rate, the larger droplets injected will produce a dilute DIC plume and thus improve the acute biological impacts but a smaller storage effective due to droplet ascending.

To date there has been little systematic research on how carbon cycle scientific information will be used to support decisions at various scales.  There is therefore a strong need to begin to understand how carbon cycle science is currently being used, who potential users might be, and how to effectively engage stakeholders and scientists on the issue.  Many assumptions are being made about the scales and information that will be of most use to decision-makers.  Decisions and information flow do not necessarily translate between scales, and thus matching the scales between provision of scientific information and scale of decision-making is critical to effectively making information useful.  This paper will examine the ways in which carbon is being or may be managed by users at various scales, characterize decision making processes of those users, and discuss implications for carbon management and science policy.

A field experiment on the Swiss Plateau was designed to measure the greenhouse gas (GHG) budget of two parallel fields after conversion from arable crop rotation to cut grassland and managed either intensively or extensively. Measurements of N₂O fluxes with chambers and of CO₂ with eddy flux towers were complemented by estimates of C-imports (organic fertilizers) and C-exports (yield). The results indicate that newly established grassland plots act as a net GHG sink when management intensity (fertilization and cutting) is high, while conversion to extensive grasslands leads to an initial net loss of GHG.

Iron fertilization has been proposed as a cheap, controllable, and environmentally benign method for removing carbon dioxide from the atmosphere. While this is in fact the case in simple, 3-box models of the carbon cycle, more realistic models show that these claims fall short of reality. The fact that the efficiency of iron fertilization depends on the long term fate of the added iron and on the carbon associated with it makes tracking the effects of iron fertilization much more difficult and expensive than has been asserted. Additionally, advection of low nutrient water away from iron-rich areas can result in lowering production remotely, with potentially serious consequences.

If liquid CO₂ is stored as a dense "lake" on the deep ocean floor, it is expected to dissolve in seawater. Ocean currents and turbulence may increase the net rate of CO₂ release by several orders of magnitude compared to molecular diffusion. However, density stratification in the seawater created by dissolved CO₂ will tend to reduce vertical mixing. By comparing results from different model formulations, this study aims to increase our understanding of the processes in such a layer of CO₂-enriched seawater, and decrease the uncertainties about storage efficiency and subsequent environmental impact. The study is also relevant to the case of saturated water leaking from subseabed geological storage through bottom sediments.

Different metrics to assess mitigation of global warming by carbon capture and storage are discussed. The climatic impact of capturing 30% of the anthropogenic carbon emission and its storage in the ocean or in a geological reservoir are evaluated for different stabilization scenarios using a reduced-form carbon cycle-climate model. The accumulated Global Warming Avoided (GWA) remains, after a ramp-up during the first ~50 years, in the range of 15 to 30% over the next millennium for deep ocean injection and for geological storage with annual leakage rates of up to about 0.001. For longer time scales, the GWA may approach zero or become negative for storage in a reservoir with even small leakage rates, accounting for the CO₂ associated with the energy penalty for carbon capture. For an annual leakage rate of 0.01, surface air temperature becomes higher than in the absence of storage after three centuries only.

Air samples are collected through the Climate Monitoring and Diagnostics Laboratory (CMDL) global network, including a cooperative program for the carbon gases which provides samples from about 100 global clean air sites, including measurements at 5 degree latitude intervals from three ship routes. Greenhouse gas concentrations are analyzed in terms of the changes in radiative forcing during the 26-year period encompassing 1979 through 2004. The growing fraction of the total radiative forcing due to carbon dioxide is emphasized and the nature of the interannual variations in the radiative forcing is explored. The interannual change in total radiative forcing is used to define an Annual Greenhouse Gas Index (AGGI).

Soil carbon sequestration has been shown to be an important part of a portfolio of carbon sequestration strategies in the U.S. and Canada, and one that can be implemented at relatively low costs [McCarl and Schneider, 2001]. The purpose of this analysis is to estimate the soil carbon sequestration potential in the North America (Canada and United States) and its impact on net terrestrial CO₂ uptake over the period 1981-2000.