Greener trees can provide early warning of volcanic awakening

Satellite images showing plant health hold vital information on stratovolcanoes in forested areas

Greener plants can be used to foretell when a volcano is about to erupt, potentially providing a warning long before more conventional methods of volcano monitoring.

An increase in carbon dioxide emissions is often one of the earliest signs of volcanic unrest, but it is hard to detect against ordinary background levels of the gas and difficult to measure directly because so many volcanoes are in inaccessible and heavily vegetated areas.