Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

98. Low-carbon liquid fuels: Schrag 2009.

99. BECCS: King et al. 2015; Sanchez et al. 2015; Schrag 2009; see also note 96 above.

100. Time headlines: Sept. 25, Oct. 19, and Oct. 14, respectively. New York Times headline: Nov. 5, 2015, based on a poll from the Pew Research Center. For other polls showing American support of climate mitigation measures, see https://www.carbontax.org/polls/.

101. Paris agreement: http://unfccc.int/paris agreement/items/9485.php.

102. Likelihood of temperature rises under the Paris agreement: Fawcett et al. 2015.

103. Decarbonization driven by technology and economics: Nordhaus & Lovering 2016. States, cities, and world vs. Trump on climate change: Bloomberg & Pope 2017; “States and Cities Compensate for Mr. Trump’s Climate Stupidity,” New York Times, June 7, 2017; “Trump Is Dropping Out of the Paris Agreement, but the Rest of Us Don’t Have To,” Los Angeles Times, June 16, 2017; W. Hamaidan, “How Should World Leaders Punish Trump for Pulling Out of Paris Accord?” The Guardian, June 15, 2017; “Apple Issues $1 Billion Green Bond After Trump’s Paris Climate Exit,” Reuters, June 13, 2017, https://www.reuters.com/article/us-apple-climate-greenbond-idUSKBN1941ZE; H. Tabuchi & H. Fountain, “Bill Gates Leads New Fund as Fears of U.S. Retreat on Climate Grow,” New York Times, Dec. 12, 2016.

104. Cooling the atmosphere by reducing solar radiation: Brand 2009; Keith 2013, 2015; Morton 2015.

105. Calcite (limestone) as a stratospheric sunscreen and antacid: Keith et al. 2016.

106. “Moderate, responsive, temporary”: Keith 2015. Removing 5 gigatons of CO2 by 2075: Q&A from Keith 2015.

107. Climate engineering increases concern about climate change: Kahan, Jenkins-Smith, et al. 2012.

108. Complacent vs. conditional optimism: Romer 2016.

CHAPTER 11: PEACE

1. The graphs in Better Angels and in this book include the most recent year available. However, most datasets are not updated in real time but are double-checked for accuracy and completeness and thus released well after the most recent year they include (at least a year, though the gap has been shrinking). Some datasets are not updated at all, or change their criteria, making different years incommensurable. For these reasons, together with the publication lag, the latest years plotted in the Better Angels graphs were before 2011, and those plotted in this book extend no later than 2016.

2. War as the default state of affairs: See the discussion in Pinker 2011, pp. 228–49.

3. In this discussion, I use Levy’s classification of great powers and great power war; see also Goldstein 2011; Pinker 2011, pp. 222–28.

4. Crisscrossing trends in great power war: Pinker 2011, pp. 225–28, based on data from Levy 1983.

5. Obsolescence of war between states: Goertz, Diehl, & Balas 2016; Goldstein 2011; Hathaway & Shapiro 2017; Mueller 1989, 2009; and see Pinker 2011, chap. 5.

6. The standard definition of “war” among political scientists is a state-based armed conflict which causes at least 1,000 battle deaths in a given year. The figures are drawn from the UCDP/PRIO Armed Conflict Dataset: Gleditsch et al. 2002; Human Security Report Project 2011; Pettersson & Wallensteen 2015; http://www.pcr.uu.se/research/ucdp/datasets/ucdp_prio_armed_conflict_dataset/.

7. S. Pinker & J. M. Santos, “Colombia’s Milestone in World Peace,” New York Times, Aug. 26, 2016. I thank Joshua Goldstein for calling my attention to many of the facts in that article, repeated in this paragraph.

8. Center for Systemic Peace, Marshall 2016, http://www.systemicpeace.org/warlist/warlist.htm, total for 32 episodes of political violence in the Americas since 1945, excluding 9/11 and the Mexican drug war.

9. Counts from the UCDP/PRIO Armed Conflict Dataset: Pettersson & Wallensteen 2015, with updates from Therese Pettersson and Sam Taub (personal communication). The wars in 2016 were: Afghanistan vs. Taliban, and vs. ISIS; Iraq vs. ISIS; Libya versus ISIS; Nigeria vs. ISIS; Somalia vs. Al-Shabab; Sudan vs. SRF; Syria vs. ISIS, and vs. Insurgents; Turkey vs. ISIS, and vs. PKK; Yemen vs. Forces of Hadi.

10. Syrian civil war battle death estimates: 256,624 (through 2016) from the Uppsala Conflict Data Program (http://ucdp.uu.se/#country/652, accessed June 2017); 250,000 (through 2015) from the Center for Systemic Peace, http://www.systemicpeace.org/warlist/warlist.htm, last updated May 25, 2016.

11. Civil wars that ended since 2009 (technically, “state-based armed conflicts,” with more than 25 battle deaths per year but not necessarily more than 1,000): personal communication from Therese Pettersson, March 17, 2016, based on the Uppsala Conflict Data Program Armed Conflict dataset, Pettersson & Wallensteen 2015, http://ucdp.uu.se/. Earlier wars with large death tolls: Center for Systemic Peace, Marshall 2016.