Rising CO2 may already be showing up in human blood — a "potentially toxic atmosphere in 50 years"

Fumikas Sagisavas / CC0 (Wikimedia Commons)

For most of human evolution, the air held about 300 parts per million of carbon dioxide. It has now surpassed 420 and is climbing by more than 2 ppm per year. A new open-access study in Air Quality, Atmosphere & Health argues that shift may already be showing up in our blood.

Alexander Larcombe and Phil Bierwirt…