From Environmental Science & Technology. March 2013

In the aftermath of the March 2011 accident at Japan’s Fukushima Daiichi nuclear power plant, the future contribution of nuclear power to the global energy supply has become somewhat uncertain. Because nuclear power is an abundant, low-carbon source of base-load power, it could make a large contribution to mitigation of global climate change and air pollution.

Using historical production data, we calculate that global nuclear power has prevented an average of 1.84 million air pollution-related deaths and 64 gigatonnes of CO2-equivalent (GtCO2-eq) greenhouse gas (GHG) emissions that would have resulted from fossil fuel burning. We calculated that in Canada, between 1971 and 2009, nuclear power has prevented an average of about 66,000 net deaths (range 16,000-264,000) and between 2.13-2.54 GtCO2-eq net GHG emissions, which corresponds with the past 20-24 years of CO2 emissions from coal burning.

On the basis of global projection data that take into account the effects of the Fukushima accident, we find that nuclear power could additionally prevent an average of 420,000-7.04 million deaths and 80-240 GtCO2-eq emissions due to fossil fuels by midcentury, depending on which fuel it replaces.

By contrast, we assess that large-scale expansion of unconstrained natural gas use would not mitigate the climate problem and would cause far more deaths than expansion of nuclear power.

It has become increasingly clear that impacts of unchecked anthropogenic climate change due to greenhouse gas (GHG) emissions from burning of fossil fuels could be catastrophic for both human society and natural ecosystems and that the key time frame for mitigating the climate crisis is the next decade or so. Likewise, during the past decade, outdoor air pollution due largely to fossil fuel burning is estimated to have caused over one million deaths annually worldwide. Nuclear energy (and other low-carbon/carbon-free energy sources) could help to mitigate both of these major problems.

The future of global nuclear power will depend largely on choices made by major energy-using countries in the next decade or so. While most of the highly nuclear-dependent countries have their plans to continue development of nuclear power after the Fukushima accident, several have announced that they will either temporarily suspend plans for new plants or completely phase out existing plants. If the role of nuclear power significantly declines in the next few decades, the International Energy Agency asserts that achieving a target atmospheric GHG level of 450 ppm CO2-eq would, according to the 2011 World Energy Outlook, require ”heroic achievements in the deployment of emerging low-carbon technologies, which have yet to be proven. Countries that rely heavily on nuclear power would find it particularly challenging and significantly more costly to meet their targeted levels of emissions.”

Our analysis strongly supports this conclusion. Indeed, on the basis of combined evidence from paleoclimate data, observed ongoing climate impacts, and the measured planetary energy imbalance, it appears increasingly clear that the commonly discussed targets of 450 ppm and 2°C global temperature rise (above pre-industrial levels) are insufficient to avoid devastating climate impacts. We have suggested elsewhere that more appropriate targets are less than 350 ppm and 1°C.

Aiming for these targets emphasizes the importance of retaining and expanding the role of nuclear power, as well as energy efficiency improvements and renewables, in the near-term global energy supply.


Pusher A. Kharecha and James E. Hansen, Nasa Goddard Institute for Space Studies and Columbia University Earth Institute.