Changes in Lake Area in Permafrost Regions of the Arctic and Tibetan Plateau from 1987 to 2017, as Revealed by a Study

As an important indicator of climate change in cold regions, changes in the lake area are important for understanding hydrological and ecological processes in cold regions.

The interaction between lakes and permafrost is complex. Previous studies have shown significant area differences in lake area variation in permafrost regions. However, the seasonal variation of lakes in permafrost regions and the conditions under which they occur are not clear.

Based on high-quality remote-sensing global water body products, a research team led by Professor Ran Yuhua of the Northwest Institute of Environment and Resources of the Chinese Academy of Sciences investigated lake area changes from 1987 to 2017 in seven carefully selected watershed permafrost areas in Arctic and Tibetan Plateau with a resolution of 30 meters, to explore the different effects of surface water balance on the change of lake area under different permafrost conditions, terrain and climate.

This study has been published in macroenvironmental science.

The study showed that the maximum surface area (seasonal and permanent) of lakes in the permafrost regions of the seven basins increased by 13.45% from 1987 to 2017. Among them, the net area of ​​seasonal lake increased by 28.66%, while that of the permanent lake increased. The net area increased by 6.39%. A total of 2.99% of the lakes’ maximum surface area disappeared, including 2.48% of the seasonal area and 3.22% of the permanent area.

In addition, the comparison between basins showed that annual lake surface area decreased in the Arctic Basin, but increased in the Tibetan Plateau.

At the lake area scale, contained lakes were classified according to the characteristics of annual area change, including no change, homogeneous changes (expansion only or contraction only), heterogeneous changes (extended lakes adjacent to shrinking lakes, EL-SL) and abrupt changes (recent lake birth or disappeared). It was found that lakes with heterogeneous changes accounted for more than a quarter of all lakes.

By comparing environmental conditions among different classifications, the researchers found that lakes with variable lake area, especially heterogeneous changes and abrupt changes, are distributed in areas with low and flat topography, high-density water bodies and high permafrost surface temperature.

“The change of surface water balance cannot fully explain the change of lake area in the permafrost zone,” said Professor Ran. “We further revealed the potential critical point impact of permafrost degradation on lake variability from a data perspective.”