Tibetan lakes estimated to expand 50% by 2100 due to climate change 

At a time when lakes are expected to shrink globally, some lakes on the Qinghai-Tibet Plateau might see their surface area increase by more than 50% by the end of the century. A new study published in Nature Geoscience on May 27 has predicted that the water volume of lakes on the plateau in southwest China could grow by over 600 billion tonnes. This increase is attributed mainly to higher rainfall from climate change and glacier melt.

Researchers indicate that if these projections hold true, itn could result in major land loss and related economic, environmental and climatic impacts. Dr. Iestyn Woolway of Bangor University (U.K.) and colleagues in China, Saudi Arabia, U.S. and France engaged in this study found that this expansion would lead to a fourfold increase in water storage compared to the past 50 years. Without mitigation measures, more than 1,000 km of roads, approximately 500 settlements, and around 10,000 sq km of ecological areas like grasslands, wetlands, and croplands could be submerged, the team warned.

“Our results suggest that by 2100, even under a low-emissions scenario, the surface area of endorheic lakes on the Tibetan Plateau will increase by over 50 per cent (around 20,000 sq km [7,722 square miles]) and water levels will rise by around 10 metres [32 feet] relative to 2020,” the scientists stated in their paper. Endorheic lakes, also known as closed lakes, do not have an outlet to drain into.

The Qinghai-Tibet Plateau, often referred to as the “Water Tower of Asia,” is the highest and largest plateau on Earth, containing over 1,000 lakes with significant water reserves in both liquid and ice forms.

“[It is] one of the regions that is most vulnerable to climate change, acting as an early warning signal for the wider effects of global warming,” the researchers noted.

While lakes in other regions have been shrinking due to rising temperatures and human activities, lakes on the plateau have been expanding due to warmer, wetter conditions driven primarily by increased net precipitation. Although glacier melt also contributes, the remaining glaciers have “limited storage,” the researchers explained.

In their study, the team developed a simulation model for 2021 to 2100, incorporating climate drivers, field surveys, and remote sensing under various socioeconomic scenarios to assess the future impact of increasing water storage on the plateau.

The northern part of the Qinghai-Tibet Plateau is projected to see the largest increase in total lake area, potentially doubling, with significant expansion expected in the southeast, northwest, and central regions as well. Even the southern part, which had been shrinking, began expanding in 2021.

Selin Co (Siling Lake), the largest lake in the Tibet autonomous region, could see its water volume increase by about 66 billion tonnes, expanding its area by approximately 800 sq km.

Despite the northern plateau’s expected large water storage increase, roads in the northeast, where there is more human activity and infrastructure, will be the most vulnerable to flooding.

In a middle socioeconomic scenario, the researchers estimated that inundated roads could lead to economic losses of US$2.7 billion to US$6.9 billion by century’s end. This “is a serious threat that should be considered in future rail and road planning,” the team advised.

The team referenced a 2011 incident where a lake in the plateau’s Hoh Xil Nature Reserve “burst,” disrupting the migration route for Tibetan antelope.

“Loss of cropland could disrupt food production, affecting both local food security and the regional agricultural economy,” they noted.

Feedback loop of warming

Dr. Woolway said, “Climate change is making the Tibetan Plateau greener and more habitable, attracting more people to higher altitudes due to better access to water. However, rising lake levels require urgent planning and policies to mitigate impacts on the region’s ecology and population.”

Several lakes are also expected to merge as their areas expand, posing threats to infrastructure and ecology.

Furthermore, the researchers highlighted concerns about increased greenhouse gas emissions, including carbon dioxide and methane, from the expanding lakes, potentially creating a feedback loop of warming and further lake expansion.

“The expanding lakes pose challenges to existing and planned infrastructure and communities and require urgent implementation of effective adaptation and sustainable management strategies to mitigate socioeconomic repercussions,” the team emphasised. “Our study serves as a scientific guide for future planning and provides valuable insights to avoid the devastating consequences of the impending lake expansion.”

Reference: https://www.nature.com/articles/s41561-024-01446-w

Image: https://unsplash.com/photos/body-of-water-between-desert-during-daytime-QFOJyx8zMn8