Record breaking CO2 AGAIN

Once again atmospheric CO2 reached its yearly maximum in May, this time hitting 420 ppm. Its been a while since I posted this update (mainly because I find it too depressing!) but here is the latest palaeo-CO2 compilation (from the IPCC Figure 2.3 - data and sources here, script here). As you can see from the plot, as far as we can tell, CO2 hasn’t been this high for at least the last 2 million years (one of the headline statements in the AR6 - based on this data). Uncertainties for this palaeo-CO2 is obviously relatively high and our data coverage is relatively poor compared to the ice core, but I wouldn’t mind betting that CO2 actually hasnt been this high for at least 3 million years. Clearly we live in unusual times!

Atmospheric CO2 reconstructed from Marine proxies and ice core methods for the last 3.5 million years. Also shown is the CO2 for May 2022 (420 ppm) and the atmospheric record from mUana Loa