Law Dome CO₂, CH₄ and N₂O ice core records extended to 2000 years BP

TLDR

Firn air measurements spanning the past 65 years overlap with the ice core and direct atmospheric observations. The new Law Dome ice core measurements extend CO₂, CH₄, and N₂O records back to 2000 BP with high resolution and precision, revealing a stable preindustrial period punctuated by up to 10 ppm CO₂, 40 ppb CH₄, and 10 ppb N₂O fluctuations, followed by a 200‑year rise in all three gases, decadal stabilization of CO₂ and slowed CH₄/N₂O growth in the 1940s–1950s, and a 100‑ppb methane increase from AD 0 to 1800 likely driven by early anthropogenic emissions.

Abstract

New measurements of atmospheric greenhouse gas concentrations in ice from Law Dome, Antarctica reproduce published Law Dome CO 2 and CH 4 records, extend them back to 2000 years BP, and include N 2 O. They have very high air age resolution, data density and measurement precision. Firn air measurements span the past 65 years and overlap with the ice core and direct atmospheric observations. Major increases in CO 2 , CH 4 and N 2 O concentrations during the past 200 years followed a period of relative stability beforehand. Decadal variations during the industrial period include the stabilization of CO 2 and slowing of CH 4 and N 2 O growth in the 1940s and 1950s. Variations of up to 10 ppm CO 2 , 40 ppb CH 4 and 10 ppb N 2 O occurred throughout the preindustrial period. Methane concentrations grew by 100 ppb from AD 0 to 1800, possibly due to early anthropogenic emissions.