The air-sea interface in a changing climate: Research advances and future directions

At the end of its second decade, the Surface Ocean-Lower Atmosphere Study (SOLAS) continues to expand critical collaborations in Earth system research, opening new gateways between the disciplines of oceanic and atmospheric science. The collection of papers in this Special Feature highlights important recent advances in air-sea interaction science, emphasizing emerging priorities and critical challenges. Since the last SOLAS synthesis in 2014, the community has gained a more nuanced understanding of the variety of marine sources of atmospheric aerosols; the influence of chemical speciation on atmospheric deposition and resulting biogeochemical impacts in the ocean; the mechanistic microscale controls of aerosol production and gas exchange at the sea surface; and also how air-sea exchange processes are influencing and responding to climate change, among numerous other advances. At the same time, SOLAS scientists have engaged more directly with socio-economic networks and in the development and evaluation of environmental and policy decisions. In addition to substantial contributions to improved understanding of the global cycling of greenhouse gases, SOLAS scientists are examining the impacts of new shipping regulations and contributing to development of frameworks for climate intervention research and governance. However, challenges remain, including characterizing the variability in air-sea gas exchange, particularly in coastal regions, and identifying mechanisms by which marine emissions influence cloud dynamics and thereby coupled marine and atmospheric feedbacks to climate change. Addressing these and other challenges requires development of innovative scientific tools (e.g., chemical sensors, expanded and integrated observational networks, machine learning algorithms), and also new inter- and trans-disciplinary collaborations, to ensure that air-sea exchange research continues to transcend boundaries in tackling current and emerging global challenges.