Successful TOAR Writing Team Meeting in York, UK

From 23 to 25 June 2025, a meeting of the lead authors of the second Tropospheric Ozone Assessment Report (TOAR) took place in the historic city of York. Participants from across the globe gathered in the impressive Guild Hall or joined remotely to discuss the current state of the assessment chapters and plan the finalisation of these papers. Martin Schultz, co-chair of TOAR phase 2, and Sabine Schröder, the main developer of the TOAR database, joined as representatives from the Earth System Data Exploration (ESDE) group of the Jülich Supercomputing Centre (JSC) at Forschungszentrum Jülich.

What is TOAR?

TOAR is a comprehensive international project that aims to assess the current state of knowledge on tropospheric ozone, i.e., ozone in the lower 12 km of the atmosphere, and to assess the impacts of ozone on human health, ecosystems, and climate. After a very successful first phase from 2014 to 2019 that was concluded with 8 peer-reviewed publications which have been cited over 1,800 times by now, the second phase of TOAR brought together around 250 scientists from more than 30 countries.

TOAR-II created a Community Special Issue with 57 articles that were submitted by November 2024 – over half of these have been published in the meantime. The ongoing assessment report, in the form of 8 papers that will be published in the esteemed "Philosophical Transactions of the Royal Society A", are heavily drawing from these publications and other information, including new analyses based on the TOAR database and other datasets.

Like TOAR-I we expect TOAR-II to be recognised and taken up by significant global stakeholders including the World Meteorological Organization (WMO), the World Health Organization (WHO), and the Global Burden of Disease (GBD), and by regional air quality fora and government organisations. For more information, visit the TOAR-II web site.