Impact of US SO2 Emission Reductions Between 1970 and 2010 on Seasonal Sulfate Aerosol Burden and Radiative Forcing Over the North Atlantic

Sagar Rathod; Daniel J. Vimont; Jack Zweifel; Salil Mahajan; Simone Tilmes; Xiaohong Liu; Wei Yi Wang; David Henderson; Tristan L'Ecuyer

doi:10.1029/2025GL115337

Impact of US SO₂ Emission Reductions Between 1970 and 2010 on Seasonal Sulfate Aerosol Burden and Radiative Forcing Over the North Atlantic

Sagar Rathod, Daniel J. Vimont, Jack Zweifel, Salil Mahajan, Simone Tilmes, Xiaohong Liu, Wei Yi Wang, David Henderson, Tristan L'Ecuyer

Research output: Contribution to journal › Article › peer-review

Abstract

Sulfate burden over the North Atlantic Ocean (NATL) exhibits strong seasonality despite no seasonality in anthropogenic sulfur dioxide (SO₂) emissions. However, the seasonality of sulfate aerosols over NATL has decreased since 1970, likely due to a reduction in the United States (US) SO₂ emissions following the Clean Air Act of 1970. We performed atmospheric chemistry and transport simulations to assess the impact of changing US SO₂ emissions between 1970 and 2010 on NATL sulfate burden and radiative forcing. United States SO₂ emission reductions weakened the seasonality in NATL sulfate burden by ∼17%, primarily due to a decrease in chemical production and transport in summer. These emission reductions caused a summertime radiative forcing (∼2 W m⁻²) twice as large as the wintertime forcing. Our findings highlight the complex, season-dependent responses of sulfate burden and radiative effects to regional emission changes.

Original language	English
Article number	e2025GL115337
Journal	Geophysical Research Letters
Volume	52
Issue number	20
DOIs	https://doi.org/10.1029/2025GL115337
State	Published - Oct 28 2025
Externally published	Yes

Keywords

aerosol
burden
forcing
North Atlantic
seasonality
sulfate

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10.1029/2025GL115337

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title = "Impact of US SO2 Emission Reductions Between 1970 and 2010 on Seasonal Sulfate Aerosol Burden and Radiative Forcing Over the North Atlantic",

abstract = "Sulfate burden over the North Atlantic Ocean (NATL) exhibits strong seasonality despite no seasonality in anthropogenic sulfur dioxide (SO2) emissions. However, the seasonality of sulfate aerosols over NATL has decreased since 1970, likely due to a reduction in the United States (US) SO2 emissions following the Clean Air Act of 1970. We performed atmospheric chemistry and transport simulations to assess the impact of changing US SO2 emissions between 1970 and 2010 on NATL sulfate burden and radiative forcing. United States SO2 emission reductions weakened the seasonality in NATL sulfate burden by ∼17\%, primarily due to a decrease in chemical production and transport in summer. These emission reductions caused a summertime radiative forcing (∼2 W m−2) twice as large as the wintertime forcing. Our findings highlight the complex, season-dependent responses of sulfate burden and radiative effects to regional emission changes.",

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doi = "10.1029/2025GL115337",

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T1 - Impact of US SO2 Emission Reductions Between 1970 and 2010 on Seasonal Sulfate Aerosol Burden and Radiative Forcing Over the North Atlantic

AU - Rathod, Sagar

AU - Vimont, Daniel J.

AU - Zweifel, Jack

AU - Mahajan, Salil

AU - Tilmes, Simone

AU - Liu, Xiaohong

AU - Wang, Wei Yi

AU - Henderson, David

AU - L'Ecuyer, Tristan

PY - 2025/10/28

Y1 - 2025/10/28

N2 - Sulfate burden over the North Atlantic Ocean (NATL) exhibits strong seasonality despite no seasonality in anthropogenic sulfur dioxide (SO2) emissions. However, the seasonality of sulfate aerosols over NATL has decreased since 1970, likely due to a reduction in the United States (US) SO2 emissions following the Clean Air Act of 1970. We performed atmospheric chemistry and transport simulations to assess the impact of changing US SO2 emissions between 1970 and 2010 on NATL sulfate burden and radiative forcing. United States SO2 emission reductions weakened the seasonality in NATL sulfate burden by ∼17%, primarily due to a decrease in chemical production and transport in summer. These emission reductions caused a summertime radiative forcing (∼2 W m−2) twice as large as the wintertime forcing. Our findings highlight the complex, season-dependent responses of sulfate burden and radiative effects to regional emission changes.

AB - Sulfate burden over the North Atlantic Ocean (NATL) exhibits strong seasonality despite no seasonality in anthropogenic sulfur dioxide (SO2) emissions. However, the seasonality of sulfate aerosols over NATL has decreased since 1970, likely due to a reduction in the United States (US) SO2 emissions following the Clean Air Act of 1970. We performed atmospheric chemistry and transport simulations to assess the impact of changing US SO2 emissions between 1970 and 2010 on NATL sulfate burden and radiative forcing. United States SO2 emission reductions weakened the seasonality in NATL sulfate burden by ∼17%, primarily due to a decrease in chemical production and transport in summer. These emission reductions caused a summertime radiative forcing (∼2 W m−2) twice as large as the wintertime forcing. Our findings highlight the complex, season-dependent responses of sulfate burden and radiative effects to regional emission changes.

KW - aerosol

KW - burden

KW - forcing

KW - North Atlantic

KW - seasonality

KW - sulfate

UR - https://www.scopus.com/pages/publications/105019346601

U2 - 10.1029/2025GL115337

DO - 10.1029/2025GL115337

M3 - Article

AN - SCOPUS:105019346601

SN - 0094-8276

VL - 52

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 20

M1 - e2025GL115337

ER -

Impact of US SO₂ Emission Reductions Between 1970 and 2010 on Seasonal Sulfate Aerosol Burden and Radiative Forcing Over the North Atlantic

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Keywords

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