Adaptation to Climate Change in Preindustrial Iceland

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