Eastham Sebastian D.

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Last Name
Eastham
First Name
Sebastian D.
ORCID
0000-0002-2476-4801

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  • Article
    Description and evaluation of the MIT Earth System Model (MESM)
    (John Wiley & Sons, 2018-08-15) Sokolov, Andrei P. ; Kicklighter, David W. ; Schlosser, C. Adam ; Wang, Chien ; Monier, Erwan ; Brown-Steiner, Benjamin ; Prinn, Ronald G. ; Forest, Chris E. ; Gao, Xiang ; Libardoni, Alex ; Eastham, Sebastian
    The Massachusetts Institute of Technology Integrated Global System Model (IGSM) is designed for analyzing the global environmental changes that may result from anthropogenic causes, quantifying the uncertainties associated with the projected changes, and assessing the costs and environmental effectiveness of proposed policies to mitigate climate risk. The IGSM consists of the Massachusetts Institute of Technology Earth System Model (MESM) of intermediate complexity and the Economic Projections and Policy Analysis model. This paper documents the current version of the MESM, which includes a two‐dimensional (zonally averaged) atmospheric model with interactive chemistry coupled to the zonally averaged version of Global Land System model and an anomaly‐diffusing ocean model.
  • Article
    Anthropogenic fingerprint detectable in upper tropospheric ozone trends retrieved from satellite
    (American Chemical Society, 2024-08-02) Yu, Xinyuan ; Fiore, Arlene M. ; Santer, Benjamin D. ; Correa, Gustavo P. ; Lamarque, Jean-Francois ; Ziemke, Jerald R. ; Eastham, Sebastian D. ; Zhu, Qindan
    Tropospheric ozone (O3) is a strong greenhouse gas, particularly in the upper troposphere (UT). Limited observations point to a continuous increase in UT O3 in recent decades, but the attribution of UT O3 changes is complicated by large internal climate variability. We show that the anthropogenic signal (“fingerprint”) in the patterns of UT O3 increases is distinguishable from the background noise of internal variability. The time-invariant fingerprint of human-caused UT O3 changes is derived from a 16-member initial-condition ensemble performed with a chemistry-climate model (CESM2-WACCM6). The fingerprint is largest between 30°S and 40°N, especially near 30°N. In contrast, the noise pattern in UT O3 is mainly associated with the El Niño–Southern Oscillation (ENSO). The UT O3 fingerprint pattern can be discerned with high confidence within only 13 years of the 2005 start of the OMI/MLS satellite record. Unlike the UT O3 fingerprint, the lower tropospheric (LT) O3 fingerprint varies significantly over time and space in response to large-scale changes in anthropogenic precursor emissions, with the highest signal-to-noise ratios near 40°N in Asia and Europe. Our analysis reveals a significant human effect on Earth’s atmospheric chemistry in the UT and indicates promise for identifying fingerprints of specific sources of ozone precursors.