Christiana Figueres and colleagues note that turning around global carbon dioxide emissions by 2020 may not be feasible through renewable energy alone (Nature 546, 593–595; 2017). Low-carbon nuclear power will be needed as well.

Historically, energy transitions take decades. When forest destruction in the time of Queen Elizabeth I forced Londoners to move from wood fuel to coal, they resisted fiercely. Many houses lacked chimneys, meat roasted over a coal fire tasted terrible, and preachers condemned the fuel as the Devil's excrement. Petroleum had little application beyond lubrication and lamp-lighting until the commercial introduction of the car in the late 1880s.

Concerns about accidents and waste disposal are delaying nuclear-power developments. Nuclear accidents have claimed fewer lives than any other energy source (A. Markandya and P. Wilkinson Lancet 370, 979–990; 2007), even including the death toll of the 2011 Fukushima disaster. Effective nuclear-waste disposal is possible: for example, the US Waste Isolation Pilot Plant near Carlsbad, New Mexico, buries waste 700 metres below ground in a 1.8-kilometre-thick bed of salt.

Moreover, nuclear power as an energy source prevented an average of 1.84 million emissions-related deaths in 1971–2009 (P. A. Kharecha and J. E. Hansen Environ. Sci. Technol. 47, 4889–4895; 2013).