Addendum: Reduced Arctic Ocean CO2 uptake due to coastal permafrost erosion

The yearly increase in atmospheric CO 2 due to Arctic coastal erosion (up to 7-13 TgC per year in ) is between three and four orders of magnitude smaller than anthropogenic CO 2 emissions, currently estimated at about 10 PgC per year 1 (1 Pg = 1,000 Tg).The rate of increase in the atmospheric CO 2 due to erosion increases with warming, which configures a positive climate feedback.The climate feedback from Arctic coastal erosion is two orders of magnitude smaller than the current central estimates of the surface albedo feedback (e.g., melting sea ice), and the cloud feedback (see Table 7.10 in IPCC AR6 WGI, Chapter 7 (ref.2)).Any impact of Arctic coastal erosion on the global climate through increasing atmospheric CO 2 concentrations until 2100 is therefore comparatively small.We find the above context important for the correct interpretation of our results, especially given the response we received after publication.Moreover in the introduction, the sentence that originally read "More than 90% of the ocean uptake of atmospheric CO 2 occurs in polar and subpolar regions" has been amended to "More than 90% of the coastal ocean uptake of atmospheric CO 2 occurs in polar and subpolar regions", referring to the work of Dai et al. 3 .