The one seeming certainty in environmental policy these days is that climate change is the most serious issue facing the world. The major policy mechanism for addressing it is also established: reduce emissions of carbon dioxide by reducing fossil fuel use. That this is an unlikely path for the world as a whole has only increased expressions of concern, even hysteria. Climate change has become the existential challenge of the environmental era.

One way or another, that existential challenge is now moot. A recent article in Science (314:452-454) suggests that atmospheric engineering (creating reflective sulfur aerosols) could counteract global warming, and a recent Ph.D. dissertation by Joshuah Stolaroff at Carnegie Mellon University, entitled Capturing CO2 from Ambient Air: A Feasibility Assessment, shows that capture of CO2 from ambient air is feasible today using known technologies. The latter estimates an approximate cost (non-optimized) of some 80 to 250 dollars per ton of CO2 reduction; further research and operating experience could reduce these numbers dramatically (higher costs had been a concern with this technology previously).

Such proposals make it clear that climate change has never been an inevitability, but a matter of values and political choice, a pricepoint issue. As Josh notes (at 4), "without air capture, CO2 levels in the atmosphere would take centuries to approach pre-industrial levels, but with air capture society can choose the desired level of atmospheric CO2 and, balanced against willingness to pay, how quickly to achieve it." There will be no global warming unless we choose to let it happen. Moreover, use of fossil fuels can continue into the indefinite future, subject to other environmental and social considerations.

But for many environmentalists and climate change scientists, this fundamental shift in the climate change debate is highly problematic, for it has long been the case that an important agenda behind climate change negotiations and the Kyoto Treaty is not responding to climate change (if it were, the world would be investing far more in technologies such as air capture, or carbon sequestration for fossil fuel plants). Rather, it is the need to socially engineer consumption patterns, especially in the United States, that are viewed as immoral, even evil.

Absent positioning climate change as a disaster avoidable only by severe reductions in consumption, how are Americans to be driven from their SUVs? Concomitantly, redistribution of wealth and resources is difficult to accomplish explicitly, so it must be done implicitly - by, for example, leveraging substantial changes in economies such as that of the US through environmental policy.

Moreover, because the effect of Kyoto has been virtually undetectable for most of the public, the question of whether all groups in global society share its implicit value prioritization has not had to be addressed. There has been no need to ask airplane passengers, or NASCAR fans, whether they want to give up services and entertainment they value, or Russia whether it wants to stabilize global climate in a configuration that leaves its northern regions frozen. But as climate becomes an issue of choice, many heretofore excluded voices need to be included in the dialog. That will require substantial change; until now, value decisions regarding climate change have essentially been the purview of scientific and environmental elites. They will resist sharing this effective control.

More subtly, Kuhn pointed out that "paradigm shifts" like this are not smooth transitions; those whose careers and reputations are dependent on climate change as crisis will tend to reject any challenge to their worldview. This would be unfortunate, for the end of global climate change as existential crisis leads not to complacency, but in fact opens up the much more difficult terrain of the anthropogenic Earth.

The transition from "simply stop doing what you're doing" to “what kind of world do you want” is not driven by fantasy, but technology and the actual state of the world. And it is not simply the climate system that is at issue, but, indeed, the interrelated networks of natural, human and built systems that define the world as it is today.

This is a huge challenge; indeed, in some ways the ideological and somewhat naïve obsession with global warming was a misleading beginning in that it temporarily hid the true magnitude of the reality facing us. But now the Anthropocene looms, and, although the work already done on climate change is a useful base from which to build, it is clear that our real work has yet to really begin.

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Brad Allenby is professor of civil and environmental engineering at Arizona State University, a fellow at the University of Virginia's Darden Graduate School of Business, and previously was AT&T's vice president of environment, health, and safety.