(p. 254) We investigate the effect of climate on population levels in preindustrial Iceland. We find that short-term temperature changes affect the population growth rate. In particular, a 1ºC decrease in temperature causes about 0.57 percent decrease in the population growth rate for the two subsequent years, for a total effect of 1.14 percent. This effect appears to attenuate as the growth rate returns to trend in subsequent years. We also quantify the extent to which eighteenth- and nineteenth-century Icelanders adapt to long-run climate change. In particular, the data suggest that long-run adaptation to climate takes about 20 years and reduces the effect of cold shocks by about 60 percent. Our results also allow us to approximate the effect of permanent climate change on steady-state population levels. This approximation suggests that steady state population levels decrease by 10 percent to 26 percent for each 1ºC of sustained adverse temperature change.
(p. 255) . . .
If contemporary poor agricultural populations behave like their eighteenth- and nineteenth century Icelandic counterparts, then our results suggest that adverse climate change (which now refers to warming, not cooling) will have three effects. First, in the short run it will lead to a significant decrease in population growth rates. Second, over the course of a generation, adaptation will offset about 60 percent of the short run effects. Finally, in the long run, we expect a decrease in steady-state populations.
For the full article, from which the above conclusion is quoted, see:
Turner, Matthew A., Jeffrey S. Rosenthal, Jian Chen, and Chunyan Hao. “Adaptation to Climate Change in Preindustrial Iceland.” American Economic Review 102, no. 3 (May 2012): 250-55.
(Note: underlining added; the underlined words appeared on p. 254 of the print issue, and on p. 255 of the online issue, of the article.)