Kopp's interest in environmental policy began in the late 1970s, when he developed techniques to measure the effect of pollution control regulations on the economic efficiency of steam electric power generation. He then led the first examination of the cost of major U.S. environmental regulations in a full, general equilibrium, dynamic context by using an approach that is now widely accepted as state-of-the-art in cost-benefit analysis.
 
During his career Kopp has specialized in the analysis of environmental and natural resource issues with a focus on Federal regulatory activity. He is an expert in techniques of assigning value to environmental and natural resources that do not have market prices, which is fundamental to cost-benefit analysis and the assessment of damages to natural resources.
 
Kopp's current research interests focus on the design of domestic and international polices to combat climate change.