Lake Heatwaves and Cold‐Spells Across Qinghai‐Tibet Plateau Under Climate Change

Abstract Lake heatwaves (LHWs) and cold‐spells (LCSs), similar to marine heatwaves and cold‐spells, can have long‐term impacts on lake ecosystems and are vulnerable to climate change. Here we first comparatively assess LHW and LCS changes across the Qinghai‐Tibet Plateau (QTP) using satellite surface water temperature observations in 160 lakes over 1978–2017. Our findings reveal notable differences in the mean and trends of LHW and LCS metrics. Specifically, total days and frequency of LHW have been increasing at a rate of 8.82 ± 1.25 days per decade and 0.78 ± 0.10 counts per decade, respectively. Conversely, total days and frequency of LCS have decreased at −6.52 ± 1.46 days per decade and −0.51 ± 0.01 counts per decade, respectively. However, average duration and mean intensity show no significant difference. Additionally, the average duration of ice cover across the QTP has been decreasing (−2.60 ± 0.38 days per decade) due to the delayed freezing date (1.13 ± 0.18 days per decade) and earlier thawing date (−1.28 ± 0.27 days per decade) during 1978–2017. Furthermore, the annual mean lake surface water temperatures across the QTP exhibit a warming trend (0.00 ∼ 0.47°C per decade) from 1978 to 2017, with faster warming occurring in winter (0.00 ∼ 0.98°C per decade) compared to summer (−0.17 ∼ 0.47°C per decade). Accelerated lake warming will increase the frequency and mean intensity of LHWs while decreasing the number of LCSs. These results help to understand how QTP lakes respond to extreme temperatures under climate change.