Your house is on fire alert:
‘For the first time in recorded history, the concentration of atmospheric carbon dioxide, or CO2, was measured at more than 420 parts per million at the Mauna Loa Observatory on the Big Island of Hawaii. It’s a disconcerting milestone in the human-induced warming of the planet, around the halfway point on our path toward doubling preindustrial CO2 levels.’
Source: Carbon dioxide is halfway to doubling pre-industrial levels – The Washington Post