Comment on egusphere-2024-1763

Abstract

Abstract. We use 2021 TROPOMI and GOSAT satellite observations of atmospheric methane in an analytical inversion to quantify national methane emissions from South America at up to 25 km × 25 km resolution. From the inversion, we derive optimal posterior estimates of methane emissions correcting the national anthropogenic emission inventories reported by individual countries to the United Nations Framework Convention on Climate Change (UNFCCC) and taken here as prior estimates. We also evaluate two alternative wetland emission inventories (WetCHARTs and LPJ-wsl) as prior estimates. Our best posterior estimates for wetland emissions are consistent with previous inventories for the Amazon but lower for the Pantanal and higher for the Parana. Our best posterior estimate of South American anthropogenic emissions is 48 (41–56) Tg a-1, where numbers in parentheses are the range from our inversion ensemble. This is 55 % higher than UNFCCC reports and is dominated by livestock (65 % of anthropogenic total). We find that TROPOMI and GOSAT observations can effectively optimize and separate national emissions by sector for 10 of the 13 countries and territories in the region, 7 of which account for 93 % of continental anthropogenic emissions: Brazil (19 (16–23) Tg a−1), Argentina (9.2 (7.9–11) Tg a−1 ), Venezuela (7.0 (5.5-9.9) Tg a−1), Colombia (5.0 (4.4–6.7) Tg a−1), Peru (2.4 (1.6–3.9) Tg a−1), Bolivia (0.96 (0.66–1.2) Tg a−1), and Paraguay (0.93 (0.88 – 1.0) Tg a−1). Our estimates align with UNFCCC reports for Brazil, Bolivia, and Paraguay, but are significantly higher for other countries. Emissions in all countries are dominated by livestock (mainly enteric fermentation) except for oil/gas in Venezuela and landfills in Peru. Methane intensities from the oil/gas industry are high in Venezuela (33 %), Colombia (6.5 %) and Argentina (5.9 %). Country-average emission factors for enteric fermentation from cattle in UNFCCC reports are in the range 46–60 kg head-1 a-1, close to the IPCC Tier 1 estimate which is mostly based on data from Brazil. Our inversion yields cattle enteric fermentation emission factors consistent with the UNFCCC reports for Brazil and Bolivia but a factor of two higher for other countries. The discrepancy for Argentina can be corrected by using IPCC Tier 2 emission estimates accounting for high milk production.

Authors 15

1. Sarah E. Hancock corresponding

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

2. Daniel J. Jacob

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

3. Zichong Chen

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

4. Hannah O. Nesser

   California Institute of Technology · Jet Propulsion Laboratory

   Affiliation as printed

   Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91011, USA

5. Aaron Davitt
   Affiliation as printed

   Climate TRACE, Denver, CO, 80022, USA

   WattTime, Oakland, CA, 94612, USA

6. Daniel J. Varon

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

7. Melissa Payer Sulprizio

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

8. Nicholas Balasus

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

9. Lucas Estrada

   Harvard University

   Affiliation as printed

   Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

10. James D. East

    Harvard University

    Affiliation as printed

    Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

11. Elise Penn

    Harvard University

    Affiliation as printed

    Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, 02138, USA

12. Cynthia A. Randles

    United Nations Environment Programme

    Affiliation as printed

    United Nations Environment Program International Methane Emissions Observatory, Paris, France

13. Ilse Aben Aachen SRON Netherlands Institute for Space Research

    Space Research Organisation Netherlands

    Affiliation as printed

    SRON Netherlands Institute for Space Research, Leiden, the Netherlands

14. Robert J. Parker

    University of Leicester · National Centre for Earth Observation

    Affiliation as printed

    Earth Observation Science, School of Physics and Astronomy, University of Leicester, Leicester, UK

    National Centre for Earth Observation, University of Leicester, Leicester, UK

15. Joannes D. Maasakkers Aachen SRON Netherlands Institute for Space Research

    Space Research Organisation Netherlands

    Affiliation as printed

    SRON Netherlands Institute for Space Research, Leiden, the Netherlands