The Air Pollution–Climate Change–Health Effects Nexus Working Group (ARCH) operates under the Global Atmosphere Watch (GAW) Programme of WMO. It strengthens research and coordination at the air-climate-health interface. For 2024–2027, it will implement a work plan to guide cooperation, capacity building, and data sharing; map GAW activities; and foster collaboration with WMO, WHO, and UNEP. ARCH will define research needs, promote integrated studies, support global initiatives like EW4All, publish an Air-Climate-Health Report, and establish a Coordination Office at Peking University.