Yale Jackson's Jessica Seddon helps translate atmospheric science for policy

Air quality and climate are deeply interconnected; for policy to effectively address one, it must account for the other. Pollutants affect climate through warming and cooling effects and cloud interactions, while climate change in turn reshapes pollution patterns — intensifying wildfires and altering the rate at which ozone forms. Maintaining and expanding observational networks — in addition to insights from satellites — are essential for tracking and anticipating these changes. 

That is the central argument of the World Meteorological Organization’s 2026 Air Quality and Climate Bulletin, whose editorial board is chaired, for the second year running, by Jessica Seddon, senior lecturer at Yale Jackson and director of the Deitz Family Initiative on Environment and Global Affairs.

"It's been fascinating and important work, tracing the connections between extremely specialized studies — like fog droplet formation in the Indo-Gangetic Plain or the specific toxicity of wildfire-generated particulate matter — and bigger questions about pollution, its sources, and policy priorities," Seddon said. "That translational work happens in the editorial meetings, and we try to do it as much as possible in how we work with the authors writing their articles."

The editorial board is drawn from working groups within the Global Atmosphere Watch program of the WMO's Science and Innovation section. Seddon said that being one of the few people with a policy and social science background among the group's atmospheric scientists gives her a distinctive role: translating technical findings into language and priorities that speak directly to policymakers.

One theme running through this year's bulletin is an emphasis on aerosols — small particles and droplets in clouds and elsewhere in the atmosphere. Aerosols have drawn mainstream attention as a visible marker of pollution and for their climate effects, through their interaction with sunlight. This year's edition set out to illustrate that nuance, demystifying particles that are often overlooked despite their ecological importance: aerosols' impact on clouds and climate, their role in glacier melt, and their effects when they settle into soil and water.

A second theme, running through the last two editions, is the data infrastructure behind atmospheric science itself. "Because information is so easy to find online now, on your phone, in dashboards, there isn't a wide appreciation of how much it takes to put the pieces of the puzzle together," Seddon said. Ground monitoring stations, vertical atmospheric observations, and satellite data all must be woven together to track what she called "a 3D moving problem of wind, water, different gases, different aerosols." This effort depends on collaboration between space agencies, environmental agencies, urban authorities, academic groups, and, potentially, private companies. To that end, the bulletin calls for expanding public-purpose global atmospheric monitoring infrastructure, particularly in underserved regions of the developing world, to strengthen early-warning systems, attribution, and other services. 

This year's edition also features new work on atmospheric deposition: the process by which pollutants return to the ground or water, whether through rainfall or gas exchange, as when plants absorb carbon dioxide or ozone. 

"There's this constant exchange between humans, plants, animals, and also between the ocean and the atmosphere, which isn't often top of mind," Seddon said. The bulletin highlights the scientific infrastructure built to track how that exchange affects soil health and water quality, through a feature on the WMO Atmospheric Deposition Initiative (WADI), alongside a feature on advances in predicting bioaerosols like pollen and allergens — forecasts for hay fever two to three days out have improved significantly, Seddon noted, a case study in how service quality evolves alongside the science.

There's this constant exchange between humans, plants, animals, and also between the ocean and the atmosphere, which isn't often top of mind,"

The bulletin also addresses wildfires, a topic of particular urgency after the fires that tore through Spain and France this summer. Over a two-week stretch in late July, fires burned through more than 600 square miles across the two countries, displacing tens of thousands. In Spain, the Burgohondo fire in Ávila province became the largest wildfire ever recorded in the country.

Seddon has served on the bulletin's editorial board for three years and has chaired it for the past two. "I hope the first thing this report does is inspire more curiosity and fascination with the atmosphere," she said. 

Atmospheric composition, she explained, is far more like the biosphere than people tend to realize. "Some areas are jungles, some are deserts, and within a jungle there are all these interactions between species. It's the same in the atmosphere, except with diverse molecules rather than plants and animals." Few people appreciate how directly these processes shape health, crop yields, biodiversity, water quality, and even cognitive processes, she said. "So many things have atmospheric roots."

The bulletin's larger policy ask, Seddon said, is simply to care more — to pause before releasing something into the atmosphere, given how what goes in ripples outward into the broader Earth system. "Until there's more of a second-nature mental model of those ripple effects, it’s hard to see how policy will really stick and be politically viable."

That work continued in September, 2026, as Seddon took part in two panel discussions during Climate Week NYC. On September 22, she joined a Yale Climate Week session on "Superpollutants: Levers for Corporate Action," and on September 23, she took part in "Climate Data 2.0: Opportunity and Urgency for Expanding Data to Ground Models, AI and Decision-making," hosted by SilverLining, a nonprofit focused on near-term climate risk research.

Explore the WMO's Air Quality and Climate Bulletin interactive infographic