Columbia International Affairs Online: Working Papers

CIAO DATE: 03/2011

The Role of Transportation in Driving Climate Disruption

Deborah Gordon

December 2010

Carnegie Endowment for International Peace


The Earth’s rapidly warming temperatures over the past several decades cannot be explained by natural processes alone. The science is conclusive: both man-made and natural factors contribute to climate change. Human activities— fossil-fuel combustion in transportation and other sectors, urbanization, and deforestation—are increasing the amount of heat-trapping gases in the atmosphere. These record levels of greenhouse gases are shifting the Earth’s climate equilibrium. Climate impacts differ by sector. On-road transportation has the greatest negative effect on climate, especially in the short term. This is primarily because of two factors unique to on-road transportation: (1) nearly exclusive use of petroleum fuels, the combustion of which results in high levels of the principal warming gases (carbon dioxide, ozone, and black carbon); and (2) minimal emissions of sulfates, aerosols, and organic carbon from on-road transportation sources to counterbalance warming with cooling effects. Scientists find that cutting on-road transportation climate and air-pollutant emissions would be unambiguously good for the climate (and public health) in the near term.