Abstract. A first regional assessment of the impact of shipping emissions on air
pollution in the Canadian Arctic and northern regions was conducted in this
study. Model simulations were carried out on a limited-area domain (at 15 km
horizontal resolution) centred over the Canadian Arctic, using the
Environment and Climate Change Canada's on-line air quality forecast model, GEM-MACH (Global
Environmental Multi-scale – Modelling
Air quality and CHemistry), to investigate the contribution from the marine shipping
emissions over the Canadian Arctic waters (at both present and projected
future levels) to ambient concentrations of criteria pollutants (O3,
PM2.5, NO2, and SO2), atmospheric deposition of sulfur (S) and
nitrogen (N), and atmospheric loading and deposition of black carbon (BC) in the Arctic.
Several model upgrades were introduced for this study, including the
treatment of sea ice in the dry deposition parameterization, chemical lateral
boundary conditions, and the inclusion of North American wildfire emissions.
The model is shown to have similar skills in predicting ambient O3 and
PM2.5 concentrations in the Canadian Arctic and northern regions, as the
current operational air quality forecast models in North America and Europe.
In particular, the model is able to simulate the observed O3 and PM
components well at the Canadian high Arctic site, Alert. The model assessment
shows that, at the current (2010) level, Arctic shipping emissions contribute
to less than 1 % of ambient O3 concentration over the eastern Canadian
Arctic and between 1 and 5 % of ambient PM2.5 concentration over the
shipping channels. Arctic shipping emissions make a much greater
contributions to the ambient NO2 and SO2 concentrations, at 10 %–50 % and 20 %–100 %, respectively. At the projected 2030
business-as-usual (BAU) level, the impact of Arctic shipping emissions is
predicted to increase to up to 5 % in ambient O3 concentration over a
broad region of the Canadian Arctic and to 5 %–20 % in ambient PM2.5
concentration over the shipping channels. In contrast, if emission controls
such as the ones implemented in the current North American Emission Control
Area (NA ECA) are to be put in place over the Canadian Arctic waters, the
impact of shipping to ambient criteria pollutants would be significantly
reduced. For example, with NA-ECA-like controls, the shipping contributions
to the population-weighted concentrations of SO2 and PM2.5 would be
brought down to below the current level. The contribution of Canadian Arctic
shipping to the atmospheric deposition of sulfur and nitrogen is small at
the current level, < 5 %, but is expected to increase to up to
20 % for sulfur and 50 % for nitrogen under the 2030 BAU scenario. At
the current level, Canadian Arctic shipping also makes only small
contributions to BC column loading and BC deposition, with < 0.1 % on
average and up to 2 % locally over the eastern Canadian Arctic for the former,
and between 0.1 % and 0.5 % over the shipping channels for the latter. The
impacts are again predicted to increase at the projected 2030 BAU level,
particularly over the Baffin Island and Baffin Bay area in response to the
projected increase in ship traffic there, e.g., up to 15 % on BC column
loading and locally exceeding 30 % on BC deposition. Overall, the study
indicates that shipping-induced changes in atmospheric composition and
deposition are at regional to local scales (particularly in the Arctic).
Climate feedbacks are thus likely to act at these scales, so climate impact
assessments will require modelling undertaken at much finer resolutions than
those used in the existing radiative forcing and climate impact assessments.
Recent Hybridization between a Polar Bear and Grizzly Bears in the Canadian Arctic