Declining greenness in Arctic-boreal lakes

The highest concentration of the world's lakes are found in Arcticboreal regions [C. Verpoorter, T. Kutser, D. A. Seekell, L. J. Tranvik, Geophys. Res. Lett. 41, 6396-6402 (2014)], and consequently are undergoing the most rapid warming [J. E. Overland et al., Arctic Report Card (2018)]. However, the ecological response of Arcticboreal lakes to warming remains highly uncertain. Historical trends in lake color from remote sensing observations can provide insights into changing lake ecology, yet have not been examined at the panArctic scale. Here, we analyze time series of 30-m Landsat growing season composites to quantify trends in lake greenness for >4 x 10(5) waterbodies in boreal and Arctic western North America. We find lake greenness declined overall by 15% from the first to the last decade of analysis within the 6.3 x 10(6)-km(2) study region but with significant spatial variability. Greening declines were more likely to be found in areas also undergoing increases in air temperature and precipitation. These findings support the hypothesis that warming has increased connectivity between lakes and the land surface [A. Bring et al., J. Geophys. Res. Biogeosciences 121, 621-649 (2016)], with implications for lake carbon cycling and energy budgets. Our study provides spatially explicit information linking climate to panArctic lake color changes, a finding that will help target future ecological monitoring in remote yet rapidly changing regions.

Automated summary

The study analyzed time series data of hundreds of thousands of lakes in the panArctic region, finding that lake greenness declined overall by 15%, with a higher likelihood in areas experiencing increases in air temperature and precipitation.