Skip to main content

Blue-green algae — which is actually a group of photosynthesizing bacteria called cyanobacteria — is coming to a river or lake near you, almost without doubt. The scourge of toxic blooms is becoming increasingly problematic worldwide, in part due to the climate crisis.

While the dumping of sewage and nutrient runoff from farms have long been known to swell the bacteria’s ranks in bodies of water, the cyanobacteria seem to be really flourishing now as global temperatures and atmospheric levels of CO2 rise.

“That, I think, is the really compelling evidence for the link to climate change—we’re seeing these increases in places where there hasn’t been a really substantial increase in urbanization or fertilizer application,” says Hans Paerl at the University of North Carolina-Chapel Hill’s Institute of Marine Sciences. “It is a global problem.”