The ongoing warming of the Earth's climate system driven by human greenhouse gas emissions — the defining environmental force of the present and future
The concentration of CO2 in the atmosphere crossed 420 parts per million in 2023 — higher than at any point in the past 800,000 years of ice core records. This is not a projection. It is a measurement. What follows from it is partly science and partly politics — and keeping those two things distinct is the beginning of understanding climate change clearly.