A study discovered that third pole darkening impacts both local and remote climates.

The Tibetan Plateau (TP) region has seen dramatic changes in its land surface as a result of the effects of global warming. These changes include the disappearance of snow cover, the greening of vegetation, and the melting of glaciers. As a result, the land surface has become darker, with a lower surface albedo and increased shortwave radiation absorption.

The surface has darkened as a result of this increase in surface temperatures. However, neither the climatic nor glaciological effects of this darkening over the TP have been evaluated or measured.

Against this background, a global team of researchers set out to find out how surface darkening over the TP would affect Asia’s remote and regional climates, led by Prof. Shilong Piao from the Institute of Tibetan Plateau Research at the Chinese Academy of Sciences.

“Given that the TP’s darkening trend is anticipated to continue in a warmer future, it is vital to close the information gap on how it will effect the climate and glacier volume in the TP as well as other distant places.”

Prof. Shilong Piao from the Institute of Tibetan Plateau Research at the Chinese Academy of Sciences.

Nature Communications published their study.

Prof. Piao explains, “Given that the darkening trend of the TP is likely to continue in a warmer future, it is critical to close the knowledge gap on how it will influence the climate and glacier volume in the TP and other remote regions.”

To investigate the effects of TP surface darkening under a high-emission scenario, the team used a high-resolution land-atmosphere global climate model (LMDZOR) and an open global glacier model (OGGM). With this arrangement, they directed two “tests” to follow the changes. The first experiment was a control with the current albedo values, and the second was a scenario with future albedo values over the TP.

Moreover, they utilized LMDZOR-reenacted close surface precipitation and air temperatures to drive the OGGM, anticipating the albedo-actuated icy mass softening before the century’s over.

The predictions suggested that the surrounding climate would be significantly affected by the surface darkening. By the end of the century, the team’s projections predicted a local temperature increase of 0.24 K. The thermodynamic forcing of the TP would be strengthened as a result of this temperature rise, preventing wind and humidity transport over South Asia while simultaneously moving moist air from the Bay of Bengal to the Indian subcontinent.

This, thus, suggested an expansion in the rainstorm precipitation over South Asia, particularly the Indian subcontinent. Additionally, an intensification of the “South Flood-North Drought” pattern in East Asia was one of the local and distant effects of the surface darkening.

In addition, the team discovered a significant loss in the western TP region and a projected loss of glacier volume of 6.9% (an increase to 25.2%). These discoveries highlight the basic effects of TP surface obscuring on the environment and hydrological balances in both neighborhood and far-off Asian rainstorm areas,” comments Prof. Piao.

“Our study can help inform policies to reduce the risk of extreme weather events, improve water allocation strategies, and support sustainable development in affected areas with this improved quantitative understanding. This includes long-term climate policies as well as ecosystem and human use of freshwater policies,” he says.

More information: Shuchang Tang et al, Regional and tele-connected impacts of the Tibetan Plateau surface darkening, Nature Communications (2023). DOI: 10.1038/s41467-022-35672-w

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