A huge wall of water and debris swept down the Teesta valley in the eastern Himalayas on October 3 2023, causing widespread devastation and the tragic loss of over 50 people. This powerful flood in India was the result of a landslide which caused a glacial lake higher up the valley to spill over. This phenomenon is known as a glacial lake outburst flood, or GLOF.
In a 2025 study of glacial lakes across the Bolivian Andes, my colleagues and I found that 11 are highly susceptible to producing potentially hazardous GLOFs. Such lakes are increasing in size and number as glaciers retreat around the world. In Bolivia, we saw 60 new lakes form in just six years.
Over the same six-year period, glaciers in the region shrank rapidly. If they continue to melt at the same rate, Bolivia will be entirely ice free by the 2080s. Unfortunately, this is likely to be a conservative estimate.
We modelled the shape of the land surface underneath the existing ice to predict where lakes might form in future. We found more than 50 potential lake sites. Further monitoring will ascertain which of these emerging lakes might pose a risk to downstream populations or infrastructure.
In our study, we used high resolution satellite imagery to monitor glaciers and glacial lakes across the Bolivian Andes. We mapped glacier and lake boundaries at annual intervals between 2016 and 2022.
Bolivia is home to nearly one-fifth of the world’s tropical glaciers. These glaciers are important in their own right, particularly during the dry season, when meltwater provides essential supplies for human consumption, agriculture and industry. Glaciers also play a role in the cultural life and heritage of Indigenous peoples in this region.
We found an alarming rate of shrinkage among these glaciers. Between 2016 and 2022, the total surface area of glaciers in Bolivia decreased by nearly 10% – at an average rate of almost two square miles per year. If these glaciers continue to retreat at the same rate, there will be none left in the region by the 2080s.
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