There are many mysteries in the Amazon. Until recently, one of the most troubling was the vast methane emissions emerging from the rainforest that were observed by satellites but that nobody could find on the ground. Around 20 million tons was simply unaccounted for.

Then Sunitha Pangala, a British postdoc researcher, spent two months traveling the Amazon’s waterways strapping gas-measuring equipment to thousands of trees. She found that trees, especially in the extensive flooded forests, were stimulating methane production in the waterlogged soils and mainlining it into the atmosphere.

Her 2014 expedition plugged a gaping hole in the planet’s methane budget. And she had discovered a…