To date, Ontario’s policy responses to climate change have primarily focused on reducing carbon dioxide emissions from both the energy and transportation sectors or methane emissions from the waste and agricultural sectors.

But scientific evidence points to opportunities presented by reducing emissions of short-lived climate forcers, principal among which is black carbon.

Black carbon exists in the atmosphere as one component of fine particulate matter (commonly referred to as soot). Scientists and policymakers have typically focused on the health effects of black carbon emissions, which are estimated to result in hundreds of thousands of premature deaths around the globe annually.

Only recently has significant attention been paid to black carbon reductions as a potential tool for climate change mitigation. The United Nation’s Environment Programme has chosen to focus attention on this issue in a recent report and the U.S. Congress directed the Environmental Protection Agency to conduct a study on black carbon’s climate and health impacts as well as mitigation options.

I’ve highlighted this opportunity in my most recent annual greenhouse gas progress report and am pleased to see the growing attention being paid to this issue. Black carbon in the atmosphere absorbs heat and thus contributes to local and regional warming, and when it settles on snow and ice it increases the absorption of sunlight which promotes melting.

This effect is particularly important in the Arctic. As the ice melts, less heat is reflected out of the atmosphere and more is absorbed by the oceans. Scientists fear that this effect constitutes a potential feedback loop for climate change because as oceans become warmer, their capacity to store carbon dioxide is diminished and thus more of it ends up in the atmosphere as global warming pollution.

As a Northern region, black carbon emissions in Ontario have a greater impact on Arctic sea ice and so the opportunity for climate change mitigation is greater.

The major sources of black carbon emissions in Ontario are transportation (both on and off-road diesel vehicles; locomotive and marine vehicles) and residential wood combustion.

Policy options are available to the Ontario government to address these sources and should be explored. For vehicles, diesel particulate filters (DPFs) are available that remove around 99 per cent of black carbon. New on-road vehicles purchased after 2007 are subject to emission controls that require DPFs, but thousands of older vehicles remain on the road without emission controls.

As well, an untold number of off-road vehicles, locomotives and marine vehicles are currently operating that have not been subject to such stringent standards. Wood stoves and fireplaces in the residential sector are another major source of black carbon that can be reduced by incentivizing the change-out of older, inefficient appliances and educating consumers about the importance of using seasoned wood that burns cleaner.

All of these mitigation options are justified based on the public health benefits of black carbon reduction alone. The added benefits for the climate are just beginning to be understood. I look forward to seeing how the Ontario government responds to this climate change mitigation opportunity.

Gord Miller is the Environmental Commissioner of Ontario, the province’s independent environmental watchdog. Appointed by the Legislative Assembly, the ECO is tasked with monitoring and reporting on compliance with the Environmental Bill of Rights, and the government’s success in reducing greenhouse gas emissions and in achieving greater energy conservation in Ontario.