1. www.bbc.com/news/uk-politics-25705550
2. Ausubel, J. H., Grübler, A. & Nakicenovic, N. Clim. Change 12, 245–263 (1988).
3. Podesta, J. D. & Wirth, T. E. Natural Gas: A Bridge Fuel for the 21st Century (Center for American Progress, 2009);
http://cdn.americanprogress.org/wp-content/uploads/issues/2009/08/pdf/naturalgasmemo.pdf
4. McJeon, H. et al. Nature 514, 482–485 (2014).
5. Brandt, A. R. et al. Science 343, 733–735 (2014).