The Aircraft Owners and Pilots Association (AOPA) has commented on a set of proposed regulations from the Environmental Protection Agency (EPA) that seek to regulate greenhouse gas emissions under the Clean Air Act, specifically targeting emissions by general aviation aircraft. The EPA’s own greenhouse gas emissions inventory shows, according to AOPA, that general aviation jets and pistons generated only 5.54 percent of the total aviation contribution and 0.74 percent of the overall transportation sector contribution. Of that 0.74 percent, 0.61 came from jet-powered aircraft and 0.13 percent from piston-powered aircraft. This compares with 81.33 percent for on-road motor vehicles, 12.53 percent for commercial and military aviation, 2.4 percent for locomotives and 2.26 percent for marine vessels. “Overall,” said AOPA, “it is inherently obvious when evaluating the data that GA’s impact on the global climate is currently and will continue to be exceedingly small. Any EPA requirement that would result in the installation of pollution controls on GA aircraft or require a change in how GA aircraft are operated would have safety and cost implications that cannot be ignored.”