ICYMI: Monthly #CO2 levels hit new milestone & went above 400 ppm for the first time on record @NOAAClimate

NOAA Climate.gov ‏@NOAAClimate  5 hours ago

ICYMI: Monthly #CO2 levels hit new milestone & went above 400 ppm for the first time on record http://climate.gov/news-features/featured-images/monthly-carbon-dioxide-levels-hit-new-milestone …