He was Distinguished Fellow at the Cato Institute from 1993 to 1996. From 1982 through 1993, he held the William E. Simon Chair in Political Economy at the Center for Strategic and International Studies, Georgetown University. During 1981-82 he served as Assistant Secretary of the Treasury for Economic Policy. President Reagan and Treasury Secretary Reagan credited him with a major role in the Economic Recovery Tax Act of 1981, and he was awarded the Treasury Department’s Meritorious Service Award for “his outstanding contributions to the formulation of United States economic policy.” From 1975 to 1978, Dr. Roberts served on the congressional staff where he drafted the Kemp-Roth bill and played a leading role in developing bipartisan support for a supply-side economic policy.
Studying my then-and-now image pairs for signs of a changing climate, I find evidence of recent forest fires, loss of river flow, and natural and unnatural geomorphologic changes such as destruction of meanders and disappearance of sandbanks. I also see the growth of invasive and water-consumptive plant species like tamarisk and Russian olive, along with an incredible greening of river valleys that were barren in the 19th century. And there are many signs of the conceit of human engineering, from ditches to dams, transforming once pristine rivers throughout the southwest into sportsmen's paradises—in other words, reservoirs—frequented by loud motorboats, harboring the gasping Asian carp and invasive quagga mussels, and heavily stocked with sport fishes; and irrigation canals, contaminated with pesticides and agricultural runoff, that largely serve dairy cows (60 percent of the water used for irrigation, or about a third of the river, goes to grow hay and forage crops , according to the Pacific Institute).