Will CO2 Reach 400 ppm? (Probably Not.)

Recently the Keeling people tweeted:

Which prompted USA to write "Carbon dioxide now at highest level in 5 million years," which naturally got WUWT's panties in a bunch.

So is CO2 going to hit 400 ppm this year? (Technically that should be "ppmv.") It already has in some northernly monitors, and of course it is already much beyond this in many cities, but will it make this number at Mauna Loa, the Yankee stadium of greenhouse gas monitoring?

It's not obvious, and it's looking a little unlikely.

Here are the recent weekly CO2 numbers from Mauna Loa:

and here is the one-year change for each week:

Lately, for whatever reason, the 1-yr change has been below average. Since last year's MLO CO2 peaked at 397.13 ppm on 5/6/12, we probably need a 2.9 ppm annual increase (assuming the peak occurs on the same week, which isn't always true), which based on the recent numbers isn't looking likely [at least for the weekly published average].

So the odds are you can put away your fireworks for another year. (Anyway, they might contribute to the increase in wildfires.)

But someday you will tell your grandchildren that you remember a distant time when CO2 was in the 300s, and they will look at you with wide open eyes, unable to even fathom the possibility of such an unspoiled world. (Well, the budding science major might -- the rest will just think you're cuckoo.)