Thompson Rivers University

Environmental Science Seminar Series

Join the Faculty of Science for our weekly Environmental Science Seminar Series every Thursday.

On Thursday, Feb. 25 at 4 p.m. join Senior Research Scientist of the Air Quality Research Division within Environment and Climate Change Canada Paul Makar as he presents Connections between air pollution, weather and climate.

Synchronous delivery will be available through BlueJeans.


Air pollution is usually thought of as a “short term” phenomena lasting days to weeks for a typical pollution episode or up to a few months for a severe event such as widespread biomass burning or forest fires.  However, atmospheric particles emitted anthropogenic or natural sources—primary particulate matter—or created by in-situ chemical reactions post-emission—secondary particulate matter—are known to have an effect on both weather and climate. These impacts result from the particles absorbing and scattering incoming solar radiation—a process known as the aerosol direct effect—and from the particles providing sites upon which atmospheric water may condense and lead to cloud formation while also altering the atmosphere’s radiative balance—aerosol indirect effect. These aerosol effects also describe a “feedback” between particles and the atmosphere in that changes to weather and climate resulting from the particles’ presence in the atmosphere may in turn change the atmospheric conditions—such as temperature, humidity, etc.—giving rise to the particles’ formation. The aerosol direct and indirect effects are known to be key factors in predicting future climates, hence their inclusion in climate change computer models. 

More recently, the impact of the aerosol direct and indirect effects on the shorter time scales of weather forecasting have been studied at Environment and Climate Change Canada and at other laboratories around the world.  The increasing consensus is that these impacts are sufficiently strong and that improved weather forecasts may result from mimicking the known feedbacks between particles and the atmosphere within a weather forecast model. The findings to date from this research will be summarized and will include high resolution coupled air-quality/weather modelling for western North America in which a significant improvement in both weather and air pollution forecasts were achieved through the use of the “feedback” version of ECCC’s Global Environmental Multiscale-Modelling Air-quality and Chemistry model (GEM-MACH). 

We further predict that climate change will influence atmospheric chemistry in the future. Simulations conducted by ECCC have shown that if air pollution emissions activities do not change, air pollution is likely to become worse with increased acute human health risks under a future warmer climate. However, changes to activities carried out to reduce greenhouse gas emissions may also reduce the emission of precursors to air pollution. We have shown that the latter changes—even when taking place under a future, warmer climate—lead to significant reductions in both air pollution and air pollution’s impact on acute human health outcomes. In other words, a potential co-benefit exists, in which activity changes designed to reduce greenhouse gas emissions may also result in improved human health. These findings, more recent work on the impacts of the same pollution emission changes on chronic human health and their potential implications, will be discussed.