Although NOAA's page on atmospheric CO2 levels has vanished, you can still get this vital information from Ralph Keeling's team at the Scripps Institution of Oceanography, UC San Diego keelingcurve.ucsd.edu
@hulavikih thank you. The GML website came back online yesterday (after ~24 hours offline I believe), but so far they haven't published the data for the month of January - they used to do it on the 5th of each month:
https://gml.noaa.gov/ccgg/trends/
@trobador @hulavikih Data still there up to Feb 21:
https://gml.noaa.gov/ccgg/trends/monthly.html