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The article examines the feasibility of scientist Paul Crutzen's idea that stratosphere should be injected with sulfate to reduce global warming. The discussions regarding the feasibility of geo-engineering of climate focuses on the following three issues: the lack of accuracy in climate prediction, the huge difference in timescale between the effect of greenhouse gases and the effect of aerosols; and serious environmental problems which may be caused by high carbon dioxide concentration.

The article reflects on a research regarding the albedo cloud enhancing through stratospheric sulphur injections to resolve some policy problems related to global warming. The research found that the global warming by the increasing concentrations of CO2 and other greenhouse gases can be countered partially by allowing backscattering of solar radiation, using sulfate particles.

So far, climate change mitigation pathways focus mostly on CO2 and a limited number of climate targets. Comprehensive studies of emission implications have been hindered by the absence of a flexible method to generate multi-gas emissions pathways, user-definable in shape and the climate target. The presented method 'Equal Quantile Walk' (EQW) is intended to fill this gap, building upon and complementing existing multi-gas emission scenarios. The EQW method generates new mitigation pathways by 'walking along equal quantile paths' of the emission distributions derived from existing multi-gas IPCC baseline and stabilization scenarios. Considered emissions include those of CO2 and all other major radiative forcing agents (greenhouse gases, ozone precursors and sulphur aerosols). Sample EQW pathways are derived for stabilization at 350 ppm to 750 ppm CO2 concentrations and compared to WRE profiles. Furthermore, the ability of the method to analyze emission implications in a probabilistic multi-gas framework is demonstrated. The probability of overshooting a 2°C climate target is derived by using different sets of EQW radiative forcing peaking pathways. If the probability shall not be increased above 30%, it seems necessary to peak CO2 equivalence concentrations around 475 ppm and return to lower levels after peaking (below 400 ppm). EQW emissions pathways can be applied in studies relating to Article 2 of the UNFCCC, for the analysis of climate impacts, adaptation and emission control implications associated with certain climate targets. See www.simcap.org for EQW-software and data. [ABSTRACT FROM AUTHOR]

In this paper, we review existing and alternative metrics of climate change, with particular emphasis on radiative forcing and global warming potentials (GWPs), in terms of their scientific performance. Radiative forcing is assessed in terms of questions such as the utility of the concept, uncertainties and sensitivity to key assumptions. The assessment of emission indices focuses on the climate and other resulting impacts (end points) against which emissions are weighted; the extent to which (and how) time dependence is included, with regard to both emission control and impact; how cost issues are dealt with; and the sensitivity of the metrics to various assumptions. It is concluded that the radiative forcing concept is a robust and useful metric of the potential climatic impact of various agents and that there are prospects for improvement by weighing different forcings according to their effectiveness. We also find that although the GWP concept is associated with serious shortcomings, it retains advantages over any of the proposed alternatives in terms of political feasibility. Alternative metrics, however, make a significant contribution to addressing important issues, and this contribution should be taken into account in the further development of refined metrics of climate change. [ABSTRACT FROM AUTHOR]

Assesses the effectiveness of an emission reduction strategy as a means of mitigating the net impact of human activities on climate for the substitution of gas for coal. Key substances included in the substitution of gas for coal; Methane emissions from coal mining and natural gas loss; Time-dependent sensitivity of the benefits of fuel switching to key options in a given gas-for-coal substitution.

Editorial. Argues that two human activities affecting global climate have been excluded in the Intergovernmental Panel on Climate Change studies and U.S. National assessments. Effect on global climate of anthropogenic land cover change; Biological effect of anthropogenically increased concentrations of carbon dioxide; Evidence presented to demonstrate the important role of human disturbances to the earth's climate.

Editorial. Argues on the views of Rodhe et al. that aerosol radiative forcing should be computed only from a bottom-up calculation using three-dimensional simulation models. Problems with bottom-up and top-down approaches to estimating aerosol radiative forcing; Avenue for constraining the aerosol radiative forcing; Principles in calculating aerosol radiative forcing.

Discusses the effect of global warming on the temporal and spatial distributions of surface water in the United States. Role of institutional factors in determining the efficacy of alternative response strategies; Development and evolution of American water institutions; Characteristics of American water rights; Challenges arising from prospective climate change.

Editorial. Asserts that an equal danger arises when mathematical models succumb to the temptations of elegance. Threat of circular reasoning; Effect of aerosols on climate; Difficulty of calculating aerosol distributions.