VENEZUELA is a tropical country, with rainforest in the south and east, and baking savannah stretching towards its northern Caribbean coast. The Sierra Nevada de Mérida mountain range in the north-west offers relief from the heat. In 1991 five glaciers occupied nooks near their peaks. Now, just one remains, lodged into a cwm west of Pico Humboldt. Reduced to an area of ten football pitches, a tenth of its size 30 years ago, it will be gone within a decade or two. Venezuela will then be the first country in the satellite age to have lost all its glaciers.

The retreat of the Humboldt glacier, named for Alexander von Humboldt, a German explorer of the 19th century, is the final stage of a 20,000-year process, the recession of an ice sheet that covered 600 square km (about 230 square miles) of Venezuela in the most recent ice age. Climate change has sped it up.

Scientists want to study the glacier in its final years but Venezuela’s tumultuous politics is making that difficult. Carsten Braun, a glaciologist at Westfield State University in Massachusetts, thinks his most recent visit in 2015 was the last by any scientific expedition. Even then, conditions were “a little dicey”. Men in military uniform pulled him off a bus and interrogated him. Now, Venezuela’s hyperinflation and rampant crime make it too dangerous to travel with the bundles of dollars needed by mountaineering scientists.

It is no longer worth hauling heavy machinery to the glacier to extract samples from it; Humboldt is too small and dirt-caked for that. But Mr Braun would like to dot it with sensors to measure water run-off, and erect weather stations to capture data on wind, temperature and barometric pressure. That would help him understand how weather influences the melting of tropical glaciers. Until Venezuela calms down, Mr Braun will be restricted to monitoring the Humboldt glacier’s decline remotely, using satellite imagery, which just reveals how fast it is melting.

That is a loss not just for science but for people in other Andean countries who rely on meltwater from tropical glaciers. In springtime that runoff is an important source of water for residents of Bogotá, Colombia’s capital, for example. Closer study of Humboldt’s decline might provide knowledge that could help them. Venezuela’s ever-deepening crisis makes it impossible for now.