Greenhouse Gas Budgets of Central and West Asia (2000–2020): A Significant Net Source to the Atmosphere

Abstract This study provides the first comprehensive quantification of three major greenhouse gases (GHGs, including CO 2 , CH 4 , and N 2 O) budgets for Central and West Asia (CWA) from 2000 to 2020, including contributions from fossil fuels, industry, and managed and unmanaged terrestrial ecosystems. We use bottom‐up (BU: inventories and process‐based models) and top‐down approaches (TD: atmospheric inversions) to elucidate CWA's GHG budget and its changes. BU and TD budgets consistently show that CWA was a significant and growing GHG source during the 2010s: average net emissions were 4,175 (range: 4,055–4,301) Tg CO 2 eq yr −1 based on BU and using global warming potentials over a 100‐year period (GWP100), and slightly higher net emissions of 4,293 (3,760–4,826) Tg CO 2 eq yr −1 based on TD. BU estimates show that CO 2 emissions from fossil fuel combustion and fugitive releases were the dominant source, accounting for 61% of the total budget in the 2010s, with 2,554 (2,526–2,582) Tg CO 2 eq yr −1 . Terrestrial natural ecosystems were a weak CO 2 sink and sources of CH 4 and N 2 O, which together resulted in a decadal mean net GHG emission of 220.5 (114.5–332.8) Tg CO 2 eq yr −1 . Non‐CO 2 gases, primarily CH 4 , contributed significantly to the region's GHG emissions, accounting for 32% (BU) and 24% (TD) of CWA's total GHG budget under GWP100, and increasing to 57% (BU) and 49% (TD) with GWP20, highlighting CH 4 stronger warming impact over shorter timescales. Overall, CWA contributed about 8% of global net GHG emissions in the 2010s, with about 10% of global CO 2 , 7% of CH 4 , and 3% of N 2 O.