Adaptation to Climate Change in Preindustrial Iceland

Abstract

We investigate the effect of climate change on population growth in 18th and 19th century Iceland. We find that a year 1• C cooler than average drives down population growth rates by 0.57% in each of the next two years, for a total effect of 1.14%. We also find that 18th and 19th century Icelanders adapt to prolonged changes in climate: these adaptations take about 20 years and reduce the short run effect of an annual change in temperature by about 60%. Finally, we find that a 1• C sustained decrease in temperature decreases the steady state population by 10% to 26%.Our analysis rests primarily on two types of data. The first is annual population data dating back to 1734. The second is imputed annual temperature data dating back to the late 1600's. We construct these data from measured temperature data and annual records of the ratio of the concentration of Oxygen-18 to Oxygen-16 in ice core strata from nearby Greenland.The resulting long time series of population and annual temperature data allow an explicit analysis of short run and long run responses to climate change. These data also allow an analysis of the way Icelanders adapt to climate change.We say that Icelanders 'adapt' to a * Turner: Department of Economics, University of Toronto, 150 Saint George Street, Toronto, Ontario, Canada m5s 3g7. Email: mturner@chass.utoronto.ca. Supported in part by sshrc. Rosenthal: Department of Statistics, University of Toronto, 100 Saint George Street, Toronto, Ontario, Canada m5s 3g3. Email: jeff@math.toronto.edu. Supported in part by nserc. Chen: Department of Statistics, University of Toronto, 100 Saint George Street, Toronto, Ontario, Canada m5s 3g3. Email: jchen@ustat.toronto.edu. Hao: Department of Statistics, University of Toronto, 100 Saint George Street, Toronto, Ontario, Canada m5s 3g3. Email: c.hao@utoronto.edu. We thank Dwayne Benjamin, Gillian Hamilton, John Munro and Gunnar Karlsson, and seminar participants at the University of Toronto for helpful comments and discussions. We also thank Benjamin Schachter and Rebecca Lindstrom for excellent research assistance. change in climate if the same event elicits a different short run response when it follows one history than when it follows another. Our data allow a direct statistical test of this commonsense notion of adaptation. Specifically, we check whether a short run climate shock has a different effect when it follows a cold history than when it follows a warm history. By repeating this test for different definitions of 'shock' and 'history', we trace out the rate of adaptation and the time-frame over which it occurs.

Climate and society in European history

“…However, this relationship was stronger for several regions prior to 1550 and considerably weaker after 1650. Studying demographics in Iceland from 1734 to 1860, Turner, Rosenthal, Chen, and Hao (2012) found a decrease in population growth for 2 years following a cold year.…”

Climate change and state evolution

“…Finally, our analysis suggests that it is highly desirable to properly combine natural and social sciences when evaluating both the short-and long-run impacts of major climate shocks. Such an interdisciplinary approach requires detailed and historically rigorous data on regional climate change, institutions, and economic outcomes but also convincing theoretical models of the interplay among these forces rising the credibility of empirical tests (5,(72)(73)(74).…”

Interdisciplinary sojourns

“…We eventually got our results published in a prestigious economics conference proceedings (Turner et al, ), and also in a statistics journal (Turner et al, ). They didn't have as much impact as I might have anticipated, perhaps because the connection to modern climate change challenges was too tenuous.…”