Climate change driving extreme acidification of North American streams that threatens life in them

As climate change drives melting of permafrost, it can produce highly acidic water that leaches ‘catastrophic’ levels of toxic metals from rocks into pristine streams, researchers in Canada have shown. The result has been a decline in vegetation over decades that appears to be accelerating recently.

Buried sulfides that originally formed in oxygen-depleted environments on Earth are widespread in permafrost. When the permafrost begins to melt, oxygen or water can oxidise them to sulfates. This then leads to runoff containing sulfuric acid, which can leach metal ions from rocks.