Underestimation of Thermogenic Methane Emissions in New York City

Joseph R. Pitt, Israel Lopez-Coto, Anna Karion, Kristian D. Hajny, Jay Tomlin, Robert Kaeser, Thilina Jayarathne, Brian H. Stirm, Cody R. Floerchinger, Christopher P. Loughner, Róisín Commane, Conor K. Gately, Lucy R. Hutyra, Kevin R. Gurney, Geoffrey S. Roest, Jianming Liang, Sharon Gourdji, Kimberly L. Mueller, James R. Whetstone, Paul B. Shepson

Research output: Contribution to journalArticlepeer-review

Abstract

Recent studies have shown that methane emissions are underestimated by inventories in many US urban areas. This has important implications for climate change mitigation policy at the city, state, and national levels. Uncertainty in both the spatial distribution and sectoral allocation of urban emissions can limit the ability of policy makers to develop appropriately focused emission reduction strategies. Top-down emission estimates based on atmospheric greenhouse gas measurements can help to improve inventories and inform policy decisions. This study presents a new high-resolution (0.02 × 0.02°) methane emission inventory for New York City and its surrounding area, constructed using the latest activity data, emission factors, and spatial proxies. The new high-resolution inventory estimates of methane emissions for the New York-Newark urban area are 1.3 times larger than those for the gridded Environmental Protection Agency inventory. We used aircraft mole fraction measurements from nine research flights to optimize the high-resolution inventory emissions within a Bayesian inversion. These sectorally optimized emissions show that the high-resolution inventory still significantly underestimates methane emissions within the New York-Newark urban area, primarily because it underestimates emissions from thermogenic sources (by a factor of 2.3). This suggests that there remains a gap in our process-based understanding of urban methane emissions.

Original languageEnglish (US)
Pages (from-to)9147-9157
Number of pages11
JournalEnvironmental Science and Technology
Volume58
Issue number21
DOIs
StatePublished - May 28 2024
Externally publishedYes

Keywords

  • Bayesian inverse modeling
  • New York City
  • airborne greenhouse gas measurements
  • emissions inventory development
  • greenhouse gas emissions
  • methane
  • urban emissions

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry

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