Sweden’s Expressen newspaper is now going to publish daily CO2 levels in the atmosphere

A little-known Swedish teenager writes Sweden’s Expressen newspaper are now going to publish daily CO2 levels in the atmosphere “due to climate emergency”!! Very hopeful! Who will be the next to follow? An even less well known English greybeard replies That's gonna be pretty dull. They don't change much day-to-day. A more hopeful colonial inquires Can they take it to hundredths of ppm or something or are there detector limits or noise overwhelming signal problems? And this is a reasonable question.

So: "reporting" on day-to-day global CO2 levels is silly, because they don't change much day to day. Indeed, the annual round of There is more CO2 in the atmosphere today than any point since the evolution of humans is dull too. CO2 is increasing, at about 2.5 ppm per year, but there's a seasonal cycle of about 4 ppm, so there's a peak every year, at which point the "news" that there's a new peak is breathlessly released. And if you were to report, daily, the global average, you'd be reporting declining CO2 levels for maybe a third of the year, which is probably not what the "climate emergency" folk want to see. But can you rescue the interest by reporting the measurements to hundredths of ppm? I don't think so.

Those global measurements are of course made up of lots of little individual measurements and the pretty graph shows how those typically vary by latitude. So, it's kinda like global temperature measurements, which are also going up but which also have a seasonal cycle and spatial variation; and the accuracy of the global average is better than the accuracy of the individual measurements.

Finally, you can look at individual measurements like the Keeling ones at Mauna Loa, and you see how they vary during the day. And you notice that the daily average is very much not the average of the hourly average. If that makes you think "aha! Gotcha you lying scientists can't even do averages properly" then you need to read Dumb America; which will lead you to Eli if you want more detail and How we measure background CO2 levels on Mauna Loa for even more excruciating detail.

Refs

* EXTINCTION REBELLION THREATENS UNDEAD LANGUAGES
* How confident are you about confidence intervals? - quiz
* Eli being rather less patient with deniers
* Less wrong isn't necessarily right - TF on How the Rural-Urban Divide Became America’s Political Fault Line by Emily Badger
* A call to climate action - Jonathan T. Overpeck, Cecilia Conde - Science  31 May 2019 / Vol. 364, Issue 6443, pp. 807 / DOI: 10.1126/science.aay1525.
* Can Journalism Be Saved? Nicholas Lemann; New York Review of Books