The prospect of potentially catastrophic global warming forces us to make decisions under extreme uncertainty. Yet, Jim Manzi writes, “Despite the rhetoric, the best available estimate of the damage we face from unconstrained global warming is not ‘global destruction,’ but is instead costs on the order of 3 percent of global GDP in a much wealthier world well over a hundred years from now.” Manzi explores how best to evaluate the costs of greenhouse gas abatement on the present-day economy when compared to the long-term benefits of avoiding global warming. He concludes that there are very few benefits from these steps.

American Progress Senior Fellow Joseph Romm argues that atmospheric CO₂ has already reached an unacceptable level, and that urgent action is needed in the next few years. Fortunately, this action need not involve prohibitive costs. Indeed, many possible options for greenhouse gas abatement will result in economic benefits.

These changes are desperately needed, too, before global warming reaches a tipping point beyond which the carbon sequestered in permafrost is also released into the atmosphere, aggravating the problem. Should we fail to act, widespread desertification, massive species extinction, and other catastrophic events are predicted, even by authorities whom Jim Manzi also accepts.

Indur Goklany argues, in response to Jim Manzi and Joseph Romm, that solving the likely problems resulting from global warming will be both cheaper and more effective than any global response aimed at stabilizing or changing the climate itself. Harm reduction will also pay important dividends regardless of the degree of global warming, since it will include the development of new treatments for diseases, better flood protection, improved crops, and general economic advancements for the developing world. When taken together, these factors will help us to face any global warming scenario effectively, and they will also offer even larger benefits outside any considerations of climate.

Michael Shellenberger and Ted Nordhaus describe what they see as a significant political realignment: Both left and right, they claim, are converging on a state-sponsored and technology-based solution to global warming, one that will emphasize clean energy and/or carbon sequestration technologies. They argue that the debate about climate modeling is largely irrelevant and/or unproductive, because these technologies are generally agreed to be important in their own right and to have positive economic effects regardless of the degree of severity of global warming. They call on policymakers to embrace a large-scale, state-funded effort to achieve these breakthrough technologies and argue that state sponsorship for technological advancement is, historically speaking, the engine of much progress and innovation. This, they argue, is a reason to embrace the same approach with regard to global warming.