Going More Slowly: Himalayan glaciers sometimes are called the “Third Pole” because of the amount of snow and ice they contain. Despite their importance as a global water reservoir and their essential role in Asian hydrology, how their mass is changing in response to global warming is not well known. Bolch et al. (p. 310 ) review the contemporary evolution of glaciers in the Himalayan region, including those of the less well sampled region of the Karakoram to the Northwest, in order to provide a current, comprehensive picture of how they are changing. Most Himalayan glaciers are retreating at rates comparable to glaciers elsewhere in the world. In the Karakorum, on the other hand, advancing glaciers are more common.

High Mountain Asia hosts the largest glacier concentration outside the polar regions. These glaciers are important contributors to streamflow in one of the most populated areas of the world. Past studies have used methods that can provide only regionally averaged glacier mass balances to assess the glacier contribution to rivers and sea level rise. Here we compute the mass balance for about 92% of the glacierized area of High Mountain Asia using time series of digital elevation models derived from satellite stereo-imagery. We calculate a total mass change of −16.3 ± 3.5 Gt yr⁻¹ (−0.18 ± 0.04 m w.e. yr⁻¹) between 2000 and 2016, which is less negative than most previous estimates. Region-wide mass balances vary from −4.0 ± 1.5 Gt yr⁻¹ (−0.62 ± 0.23 m w.e. yr⁻¹) in Nyainqentanglha to +1.4 ± 0.8 Gt yr⁻¹ (+0.14 ± 0.08 m w.e. yr⁻¹) in Kunlun, with large intra-regional variability of individual glacier mass balances (standard deviation within a region ∼0.20 m w.e. yr⁻¹). Specifically, our results shed light on the Nyainqentanglha and Pamir glacier mass changes, for which contradictory estimates exist in the literature. They provide crucial information for the calibration of the models used for projecting glacier response to climatic change, as these models do not capture the pattern, magnitude and intra-regional variability of glacier changes at present. Publisher Correction (18 June 2018)

A deadly cascade: A catastrophic landslide in Uttarakhand state in India on February 2021 damaged two hydropower plants, and more than 200 people were killed or are missing. Shugar et al. describe the cascade of events that led to this disaster. A massive rock and ice avalanche roared down a Himalayan valley, turning into a deadly debris flow upstream from the first of the two hydropower plants. The sequence of events highlights the increasing risk in the Himalayas caused by increased warming and development. Science , abh4455, this issue p. 300