CO2 Concentration Exceeds 400 ppm

A significant milestone was passed in May, 2013 when the the concentration of CO2 in the atmosphere exceeded 400 parts per million (400 ppm) for the first time in recorded history. This was the highest CO2 concentration in more than 800,000 years. Despite the significance of the event, deniers downplayed it by saying it crossed over the 400 ppm threshold only 'briefly.' There was some truth to that because it stayed above 400 ppm for only a few days before it began it annual decline. But, where were these people when it stayed over 400 ppm for about four months in 2014?

Now, the bad news is we have already reached the 400 ppm level this year. The daily average reading from January 1, 2015 was for 400.37 ppm.

Source: SIO

NOAA actually reports it as 401.56 ppm. We can expect it to fluctuate up and down, so it won't stay above 400 and, in fact, NOAA reports the level as 399.91 ppm for January 2nd. But, the earliest it reached this level in 2013 was in May. The earliest it reached this level in 2014 was March. And, now we are seeing this level in January. There can be no doubt we are nearing the time when the CO2 level will never again drop below 400 ppm. My guess? 2016 will be the last year that will ever have CO2 levels less than 400 ppm. At least, for the next thousand years, or more. Here is the two-year plot of CO2 levels as measured at Mauna Loa, Hawaii.