Impacts of marine cloud brightening scheme on climatic extremes in the Tibetan Plateau

As an ecologically fragile plateau and major water source in Asia, the Tibetan Plateau (TP) has grown warmer over recent decades, contributing to frequent occurrence of extreme climate events. It is urgently needed to find a suitable option to mitigate climate change impacts in the TP. The marine cloud brightening (MCB) scheme is proposed to mitigate global warming through the increasing cloud droplet number concentration of low marine clouds to reflect some solar radiation back into space. Until now, impacts of MCB scheme on the TP have not been investigated. In this study, we utilized 13 Expert Team on Climate Change Detection and Indices to assess the evolution of climate extremes over the TP with/without MCB implementation. We found that although the MCB is implemented over ocean only, it would cause significant changes on climate extremes in the TP which is very far from oceans and much higher than sea level. During 2030–2059, MCB implementation can decrease warm temperature extremes, leading to a significant decrease in the TXx index by 6–18°C, the TX90p index by 15–45 days, and the TN90p index by 15–50 days. MCB implementation would also have some cooling effects on cold temperature extremes, leading to an increase in the ID index by 30–80 days, the TX10p index by 22–32 days, and the TN10p index by about 12 days and a decrease in the TNn index by 0.5–1.5°C. Although MCB implementation would not have much impacts on precipitation extremes, it would significantly increase the area of the region with <10% drought frequency, and increase the drought intensity in the west of Lhasa city.