The 2023 ACP Paul Crutzen Publication Award

26 March 2024

Atmospheric Chemistry and Physics has named two joint recipients of the 2023 ACP Paul Crutzen Publication Award, plus eight shortlisted articles. The award was created to recognize an outstanding publication in ACP that advances our understanding of atmospheric chemistry and physics. The annual award was created in honour of Paul Crutzen, Nobel Prize laureate and former director of the Max Planck Institute for Chemistry, who played a pivotal role in the creation of the journal 22 years ago.

The prize publications were selected by an independent committee, with members Annica Ekman (chair, Stockholm University), SK Satheesh (Indian Institute of Science, Bangalore), Susan Solomon (MIT), Steve Sherwood (University of New South Wales), John P. Burrows (University of Bremen), Ulrike Lohmann (ETH Zurich), Sonia Kreidenweis (Colorado State University), and Hiroshi Tanimoto (National Institute for Environmental Studies, Japan).

This year's recipients for a paper published in 2023 are

Detection of large-scale cloud microphysical changes within a major shipping corridor after implementation of the International Maritime Organization 2020 fuel sulfur regulations
Michael S. Diamond
Atmos. Chem. Phys., 23, 8259–8269,,, 2023
Long-term monitoring of cloud water chemistry at Whiteface Mountain: the emergence of a new chemical regime
Christopher E. Lawrence, Paul Casson, Richard Brandt, James J. Schwab, James E. Dukett, Phil Snyder, Elizabeth Yerger, Daniel Kelting, Trevor C. VandenBoer, and Sara Lance
Atmos. Chem. Phys., 23, 1619–1639,,, 2023

The study by Michael S. Diamond found strong evidence that droplet sizes reduced and clouds became less reflective after 2020, following the restrictions on sulfur emissions from shipping. In addition to their geophysical significance, the results provide independent evidence for general compliance with the 2020 regulations. The award committee described the paper as innovative and timely, with high societal relevance. Michael S. Diamond says that "cleaning up ship pollution has been a 'silver cloud with a dark lining'; we can already see that the resulting cloud changes are speeding up global warming by a small, yet meaningful, amount. These results underscore the importance of reducing aerosol and greenhouse gas emissions at the same time. This 'unintentional experiment' will also be a valuable source of information for proposals to deliberately seed clouds to temporarily offset some climate change impacts."

In the study by Christopher E. Lawrence and co-authors, long-term trends in cloud water chemical composition from 1994 to 2021 show the emergence of a new chemical regime dominated by organics and ammonium, which is quite different from the highly acidic regime observed in the past. The award committee highlighted the innovative nature of the study, and the clever use of long-term observations with novel methods, with the potential for a high impact on policy because it points out that current air quality monitoring may not be appropriate. Christopher E. Lawrence and the corresponding author, Sara Lance, said, "We are honoured to accept this award and grateful for all the people involved in supporting the long history of cloud water chemistry measurements at Whiteface Mountain, providing the foundation upon which the research presented in this paper rests. In particular, we are grateful that the decision was made in 2009 to add organic carbon to the routine chemical measurements, which we hope may continue for many years, as these measurements have enabled us to better identify the emergence of a new chemical regime, with important implications for air quality, climate, and ecosystem health."

Congratulations are also extended to the authors of eight further papers which were shortlisted for the award. These articles made important advances in our understanding of heterogeneous ice nucleation, global temperature trends, biogenic emissions, secondary organic aerosol, methane trends and super-emitters, and wildfires, as well as one of ACP's 20th anniversary Opinion articles on deep convective cloud responses to aerosol. These articles are listed on the ACP Paul Crutzen Publication Award web page.