Since the Intergovernmental Panel on Climate Change (IPCC) was formed in 1988, it has engaged a substantial proportion of those individuals with relevant scientific expertise in the process of forming reasonable judgments about the effects of aggregate human activity on the composition of the earth"s atmosphere and about the resulting implications for global climate. It is now widely agreed that in concert with other so-called "greenhouse gases," carbon dioxide (CO2) released from the burning of fossil fuels for energy is causing the earth"s climate to change. Over the last century, the concentration of CO2 in the atmosphere increased from about 300 to 375 parts per million by volume (ppmv), and global average surface temperature increased by 0.4 to 0.8 oC. In the absence of policies designed to substantially reduce global emissions, scenarios developed by the IPCC indicate that CO2 concentrations will reach 550 to 1000 ppmv in 2100 and that global average surface temperature will increase by an additional 1.5 to 6 oC (IPCC 2001a).
The consequences of such a temperature increase and associated changes in precipitation patterns and other climate variables are a matter of greater uncertainty and disagreement. At the lower end of the range, it is possible that nothing of global consequence will occur, and that the regional and more localized effects will be moderate enough to be handled by natural adaptation. It also conceivable"particularly at the high end of the temperature range"that abrupt, nonlinear and fundamental changes could be triggered, such as a sudden change in large-scale ocean currents, with truly massive and potentially catastrophic consequences for human societies. The IPCC has identified the possibility of extreme danger, but has been and will remain unable to reach consensus on its exact character, magnitude, probability and timing.
That situation presents an extraordinary problem of risk management. It is feasible in principle but monumentally demanding to limit the atmospheric concentration of greenhouse gases resulting from aggregate human activity. Moreover, the will and capacity to do so would have to be generated in advance of scientific consensus about the danger to be avoided. If business continues as usual, however, any scientific consensus that might form about catastrophic climate change is likely to emerge only after it is too late to take action to avoid it.
Any effort to reduce emissions which restrains global economic output threatens the developing world with prolonged stagnation and hopelessness, setting the stage for increased civil conflict and international violence. Although the relevant relationships are not yet understood in detail, it is widely suspected that violence is generated by the sustained denial of economic opportunity. Thus, security in the globalized world economy ultimately depends on a more equitable pattern of economic development than has yet been achieved.
Steve Fetter is dean of the School of Public Policy at the University of Maryland.
Tim Gulden is a Research Fellow at the Center for International and Security Studies at Maryland.