Preprints
https://doi.org/10.5194/egusphere-2024-1428
https://doi.org/10.5194/egusphere-2024-1428
17 May 2024
 | 17 May 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Warming effects of reduced sulfur emissions from shipping

Masaru Yoshioka, Daniel P. Grosvenor, Ben B. B. Booth, Colin P. Morice, and Kenneth S. Carslaw

Abstract. The regulation introduced in 2020 that limits the sulfur content in shipping fuel has reduced sulfur emissions over global open oceans by about 80 %. This is expected to have reduced aerosols that both reflect solar radiation directly and affect cloud properties, with the latter also changing the solar radiation balance. Here we investigate the impacts of this regulation on aerosols and climate in the HadGEM3-GC3.1 climate model. The global aerosol effective radiative forcing caused by reduced shipping emissions is estimated to be 0.13 W m-2, which is equivalent to about 50 % of the positive forcing caused by the global reduction in all anthropogenic aerosols since late 20th century. Ensembles of global coupled simulations from 2020–2049 predict a global mean warming of 0.04 K averaged over this period. Our simulations are not clear on whether the global impact is yet to emerge or has already emerged because the present-day impact is masked by variability. Nevertheless, the impact of shipping emission reductions will have either already committed us to warming above the 1.5 K Paris target or will represent an important contribution that may help explain part of the rapid jump in global temperatures over the last 12 months. Consistent with previous aerosol perturbation simulations, the warming is greatest in the Arctic, reaching a mean of 0.15 K Arctic-wide and 0.3 K in the Atlantic sector of the Arctic (which represents greater than 10 % increase in the total anthropogenic warming since pre-industrial times).

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Masaru Yoshioka, Daniel P. Grosvenor, Ben B. B. Booth, Colin P. Morice, and Kenneth S. Carslaw

Status: open (until 02 Jul 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1428', Anonymous Referee #1, 17 Jun 2024 reply
  • RC2: 'Comment on egusphere-2024-1428', Anonymous Referee #2, 19 Jun 2024 reply
Masaru Yoshioka, Daniel P. Grosvenor, Ben B. B. Booth, Colin P. Morice, and Kenneth S. Carslaw
Masaru Yoshioka, Daniel P. Grosvenor, Ben B. B. Booth, Colin P. Morice, and Kenneth S. Carslaw

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Short summary
Sulfur emissions from shipping has been reduced by about 80 % as a result of the new regulation introduced in 2020. This has reduced aerosol in the atmosphere and its cooling effect through interactions with clouds. As a result, our coupled climate model simulations predict a global warming of 0.04 K averaged over three decades, potentially surpassing the Paris target of 1.5 K or contributing to recent temperature spikes, particularly notable in the Arctic with a mean warming of 0.15 K.