Indonesia investigates whether deforestation worsened cyclone senyar’s deadly impact on sumatra

Indonesia is examining whether decades of environmental destruction amplified the catastrophic damage from Cyclone Senyar, which devastated northern Sumatra in November 2025. The rare tropical cyclone killed at least 1,178 people and displaced around one million others across three provinces, making it one of Indonesia’s deadliest natural disasters in recent history.

The epicenter of destruction was the Batang Toru forest landscape, famous as the last refuge of the world’s rarest great ape, the Tapanuli orangutan. While Cyclone Senyar’s extreme rainfall provided the immediate trigger for devastating flash floods and landslides, scientists argue that decades of deforestation and landscape alteration significantly worsened the disaster’s impact. “Extreme weather was only the initial trigger,” said Erma Yulihastin, a climate researcher at Indonesia’s National Research and Innovation Agency. “The destructive impact was shaped by weakened environmental buffers upstream.”

The government appears to acknowledge this connection. On December 23, Environment Minister Hanif Faisol Nurofiq announced an investigation into eight companies operating in the Batang Toru watershed to determine whether their mining, energy, and plantation activities contributed to the catastrophe. All eight companies have been ordered to suspend operations pending the investigation.

The disaster has transformed this biodiversity hotspot into a crucial test case for Indonesia’s commitment to enforcing environmental law, particularly in regions where industrial development overlaps with fragile ecosystems that serve as natural disaster buffers.