CO2 emission reduction assumptions overly optimistic, says study

Technological challenges of reducing CO2 underestimated by IPCC, according to CU-Boulder-led study

Reducing global emissions of carbon dioxide this century is going to be more challenging than society has been led to believe, according to a new research commentary article appearing April 3 in Nature.

The authors, from the University of Colorado at Boulder, the National Center for Atmospheric Research in Boulder and McGill University in Montreal, said the technological challenges of reducing CO₂ emissions have been significantly underestimated by the Intergovernmental Panel on Climate Change. The study concludes the IPCC is overly optimistic in assuming that, even without action by policymakers, new technologies will result in dramatic reductions in the growth of future emissions.

Recent changes in “carbon intensity” -- CO₂ emissions per unit of energy consumption -- already are higher than those predicted by the IPCC because of rapid economic development, said lead author and CU-Boulder Professor Roger Pielke Jr. of the environmental studies program. In Asia, for instance, the demands of more energy-intensive economies are being met with conventional fossil-fuel technologies, a process expected to continue there for decades and eventually move into Africa.

The IPCC underestimate of carbon intensity is due in part to the panel’s differing scenarios tied to global emission changes expected to occur spontaneously and those driven by climate policies, according to the Nature authors. Titled “Dangerous Assumptions,” the Nature commentary was co-authored by Senior Scientist Tom Wigley of NCAR’s Climate and Global Dynamics Division and economics Professor Christopher Green of McGill University’s Global Environmental and Climate Change Center.

“According to the IPCC report, the majority of the emission reductions required to stabilize CO₂ concentrations are assumed to occur automatically,” said Pielke. “Not only is this reduction unlikely to happen under current policies, we are moving in the opposite direction right now. We believe these kind of assumptions in the analysis blind us to reality and could potentially distort our ability to develop effective policies.”