Earth’s atmosphere hit 400 parts per million of carbon dioxide last month — the highest level humans have ever experienced. This can be easily tracked here through measurements at an observatory on Mauna Loa in Hawai’i. The Keeling Curve (which really appears as more of a line pointing upwards) is named after the man who started taking the measurements in 1958.
The massive spike in carbon dioxide has been observed in other forms of measurement, though Mauna Loa provides an unsettlingly transparent demonstration of what happens when a species burns up a lot of carbon that had been underground for millions of years.
How much has your lifestyle contributed to this rise in emissions? What were you likely doing when the planet passed this inauspicious milestone?