"The CO2 measured at the Mauna Loa Baseline Atmospheric Observatory in Hawaii hit 405.1 parts per million last year, the National Oceanic and Atmospheric Administration announced. That’s an increase of 3 parts per million, which matched the record of 3 parts per million in 2015. It marks five consecutive years of CO2 increases of at least 2 parts per million, an unprecedented rate of growth, said Pieter Tans, lead scientist at NOAA’s Global Greenhouse Gas Reference Network."

“The rate of CO2 growth over the last decade is 100 to 200 times faster than what the Earth experienced during the transition from the last ice age,” Tans said. “This is a real shock to the atmosphere.”

"The number is significant because the amount of carbon dioxide in the atmosphere was 280 parts per million from about 10,000 years ago until the start of the Industrial Revolution. The monthly global average nosed above 400 parts per million for the first time in March 2015 and is now increasing at a faster pace, according to NOAA researchers. What’s more, carbon emissions stay in the atmosphere for years, so even as some emissions have been reduced in recent years, the global average level continues to climb. In 1960, they were about 300 parts per million, suggesting a precipitous climb in a relatively short period of time since then."