Climate Action Days: The Caves of Laos — Hidden Libraries of Climate and History

In January 2026, the third Bulgarian caving expedition to Laos and the wider region (Indochina) was carried out. 

The focus was on little-studied caves that are largely unknown to the public in the “karst heart” of Laos—Central Laos. The aim of the expedition was to explore and promote the caves there, thereby laying the groundwork for future scientific expeditions with Bulgarian participation.

Laos is a karst region, part of the vast South China Karst Plateau. It is believed to contain over 10,000 caves, only a very small fraction of which have been documented and studied. A distinctive feature of these caves is their enormous scale: they have wide entrances and galleries tens of meters across—some reaching cathedrallike heights.

They are also very warm and humid, which creates ideal conditions for the formation of abundant cave deposits, huge and impressive stalactites and draperies.Most importantly, however, these caves are in fact hidden climate libraries: within them are records of climate change, both from the surface environment and from processes occurring inside the caves themselves.

For us Europeans there is yet another important and fascinating aspect of caves in Laos: they are closely tied to the culture and religion of local communities. There are strong traditions that caves must be protected, and we did not see a single broken piece, even in the most heavily visited caves. Even the smallest break can effectively erase tens of thousands of years of climatic history. It would be very good if we could adopt more of this cave-protection ethic (especially we in Bulgaria).