Science and Policy Interactions in North America Over 50 Years

Ellis Cowling, Founding Leader of the US’ National Atmosphere Deposition Program and University Distinguished Professor At-Large at North Carolina State University

Presentation: Ellis Cowling.pdf

Following Svante Oden’s audacious headline about an “insidious chemical warfare among the Nations of Europe,” scientists in Canada and the United States followed the European example of establishing networks of monitoring stations to determine spatial and trends in the chemistry of rain and snow in both countries – CAPMON in Canada and NADP in the US.

These networks quickly confirmed that acidifying deposition was occurring in large regions of both countries; was associated with both short-distance and long-distance transport of SO2 and NOx emissions from tall stacks at coal-fired power plants, metal smelters, and other industries; transport of SO2 and NOx was frequently occurring across both national and state and provincial borders; and acid deposition was leading to acidification of lakes, streams, soils, and drinking water reservoirs.

Major disputes developed between both Canada and the US and between leaders in various industries and environmentalists concerned about acidification impacts on fish populations, drinking water quality, and both agricultural crops and forest trees. These disputes led to creation of major acid rain research programs in several provinces of Canada and the huge 10-year long National Acid Precipitation Assessment Program (NAPAP) in the United States.

Within months after completion of NAPAP, both Canada and the US gave up their rancorous debates and agreed to sign the 1991 Canada-United States Air Quality Agreement which includes commitments to achieve major decreases in emissions of SO2 and NOx in the major industries of both countries and increased concern about tropospheric ozone (O3).

During the nearly 27 years since this Agreement was signed, SO2 emissions in the US were decreased by about 90% and by about 70% in Canada. Also, NOx emissions were decreased by a bit more than 80% in both countries.

The US achieved most of its decreases in SO2 emissions from electric generating units by developing the world’s first major “Cap and Trade Program” for air pollution control purposes.

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