Just as Mauna Loa goes over 400 ppm, Ralph Keeling is featured in a Webcast today held by the Yale Forum. 3 pm Eastern Time, 12 pm on the West Coast. Britton Stephens is also participating, and Bruce Lieberman is hosting. They're taking questions by email.
As you might know, the Mauna Loa observing station is being threatened by budget cuts. Which is nearly inexplicable -- the atmospheric CO2 content may be the most important number on the planet. Imagine if Dow Jones stopped monitoring the stock market.
CO2 at Mauna Loa is already over 400 ppm. Last year this barely happened, and only at the anual peak (when the planet's vegetation is at its minimum). This year it should peak at about 401.5 to 402.5 ppm, and since the annual cycle varies by about 6-7 ppm top-to-bottom, MLO CO2 will be permanently above 400 ppm in about 2 more years.
Unless they get those CO2-sucking machines working. (Then find a place to put it all.) For sale: 30 billion tons of carbon dioxide. Lightly used. Buyer must arrange for transportation.