Mysterious chemicals are being emitted by the Amazon trees during droughts
The air above the Amazon smells the way it does because of chemicals the trees are constantly releasing. Researchers have been measuring those compounds for years, and most of the time the mix is predictable enough that any big departure reads like a distress signal. During and after the record-shattering drought of 2023 and 2024, the readings showed something no one had seen there before. Molecules that had never been detected in the rainforest’s air appeared above the canopy – and they kept appearing long after the rains came back. Trees send distress signals Plants give off a whole family of airborne compounds. The lightest, isoprene, makes the blue haze over forested mountains. Heavier and far rarer are the sesquiterpenes, larger molecules trees release when something is wrong. One of them, caryophyllene, gives cloves and black pepper their warm bite. Trees release sesquiterpenes as distress signals and protective chemicals, guarding their tissues when heat, drought, or pests push ...