“400 ppm was long considered a very serious measurement but it isn’t the end — it’s just a marker on the road to ever-increasing carbon pollution levels…’It is a milestone, marking the fact that humans have caused carbon dioxide concentrations to rise 120 ppm since pre-industrial times, with over 90 percent of that in the past century alone. We don’t know where the tipping points are.'”
Kepler 186f or bust? After flirting with 400ppm last May, carbon dioxide levels in the atmosphere reach 402 parts-per-million, the highest levels in at least 800,000 years. “When asked if the 400 ppm will be reached even earlier next year, Butler responded simply, “‘Yes. Every year going forward for a long time.'”
