Current Composition of the Atmosphere, July 2025

 Guest post by Jim

Abstract

Total forcings are total 535 ppm CO2 eq, less than 20 ppm CO2 eq from twice the pre-industrial amount. The 2x crossing is now estimated to occur 28 February, 2030. The leading greenhouse gases, in terms of radiative forcings, are carbon dioxide (426 ppm CO2 eq, 79.7%), methane (54.5  ppm CO2 eq, 10.2%), and nitrous oxide (17.8 ppm CO2 eq, 3.32%); 

Results

I am a bit uneasy everytime that I check out NOAA's Global Monitoring Laboratory's data, Trends in CO2, CH4, N2O, SF6. Will the data be there? Will the updates appear in a timely manner? They used to be posted 5th of each month or the next business day, regular as clockwork. Not so much, these days.

Here are the updated results. Little has changed. By 2030 the atmosphere will have such a high concentration of greenhouse gases that the effective radiative forcing will be  twice that of the pre-industrial era. 

The 2x crossing is now estimated to occur 28 February, 2030 give or take a month; just as in previous months, changes in this estimate over the last year are more likely due to month-to-month fluctuations, not long term changes in trends. 

Total forcings are total 535 ppm CO2 eq, less than 20 ppm CO2 eq from twice the pre-industrial amount. It is clear that, within a handful of years the 2x pre-industrial level will be crossed.

The leading greenhouse gases, in terms of radiative forcings, are carbon dioxide (426 ppm CO2 eq, 79.7%), methane (54.5  ppm CO2 eq, 10.2%), and nitrous oxide (17.8 ppm CO2 eq, 3.32%); all others contribute the rest (35.9  ppm CO2 eq (6.7%). 

Here is a pie chart showing these relative forcings. Carbon dioxide, of course, is the largest contributor but methane is not insignificant and has been relatively increasing.

Here is a plot showing the combination of historic data, satellite era data, and the most recent updates from NOAA:

OG: Thanks, as usual, Jim! Wish it were better news.