Analysis of Taiga and Tundra Lake Browning Trends from 2002 to 2021 Using Modis Data

Taiga and tundra regions have a high density of lakes and are undergoing significant climate changes. Previous field studies have proven that lake color is associated with primary productivity and dissolved organic carbon concentrations, which may be influenced by terrestrial processes. However, the prolonged browning trend of lakes in taiga and tundra biomes has not been well understood. This study conducted a large-scale trend analysis of lake color in the near ultraviolet wavelengths using MODIS Band 8 surface reflectance values to quantify trends in lake brownness for 7616 lakes (larger than 10 km2) in taiga and tundra biomes from 2002 to 2021 on the Google Earth Engine platform. Overall, the study lakes in taiga and tundra showed a decreased trend in browning (Theil-Sen slope = 0.00015). Of the 7476 lakes, 2688 (about 36%) lakes showed browning trends, and 87 (about 1.16%) lakes had a significant increase in brownness (p﹤0.05). The results indicate that browning trends were more likely to occur in shallow andsmall lakes with low ground ice content in higher latitude areas that are warmer and drier. Further, our results also support the hypothesis that climate warming has increased the linkage between lakes and the land surface, with implications for lake carbon cycling and energy budgets. This study provides spatially explicit information linking climate to pan-Arctic lake color changes, and this finding will help target future ecological monitoring in remote yet rapidly changing regions