William Nordhaus' View On Cutting GHG Emissions Darkens; We're Not Even Close To Needed Reductions

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In the early 1990s, Yale's William Nordhaus was among the first to examine the economics of reducing carbon emissions. Since then, he and colleagues have mixed climate physics with economic modeling to explore how various policies might play out both for global temperatures and growth. The approach attempts to weigh, in present-value terms, the costs of preventative measures against the future benefit of avoiding disaster.

Nordhaus has mostly argued for a small carbon tax, aimed at achieving a modest reduction in emissions, followed by sharper reductions in the medium and long term. Too much mitigation now, he has suggested, would damage economic growth, making us less capable of doing more in the future. This view has helped fossil fuel companies and climate change skeptics oppose any serious policy response.

In his latest analysis, though, Nordhaus comes to a very different conclusion. Using a more accurate treatment of how carbon dioxide may affect temperatures, and how remaining uncertainties affect the likely economic outcomes, he finds that our current response to global warming is probably inadequate to prevent temperatures from rising more than 2 degrees Celsius above their pre-industrial levels, a stated goal of the Paris accords. Worse, the analysis suggests that the required carbon-dioxide reductions are beyond what's politically possible. For all the talk of curbing climate change, most nations remain on a business-as-usual trajectory. Meanwhile, further economic growth will drive even greater carbon emissions over coming decades, particularly in developing nations.

Nordhaus deserves credit for changing his mind as the results of his analyses have changed, and for focusing on the implications of current policies rather than making rosy assumptions about the ability of new technologies to achieve emission reductions in the future. Many other analyses -- including those of the Intergovernmental Panel on Climate Change -- don't demand such realism.

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http://www.bloombergquint.com/business/2017/01/31/a-climate-change-economist-sounds-the-alarm