This brief describes issues relevant to the timetable for reducing U.S. emissions of greenhouse gases (GHGs) under a
cap-and-trade program. The first issue is whether reductions are sufficiently deep to have a meaningful effect on the global climate. Scientific evidence suggests that global reductions of 50 to 85% by 2050 are needed to avoid the most serious consequences of climate change, and policymakers need to decide what share of the global emission reduction burden will be shouldered by the United States. Second, while existing technologies can be used to make significant near-term emission reductions, new technologies will be needed to achieve deep long-term reductions. Policymakers can stimulate technology development with a sufficiently stringent timetable that covers several decades. Cost minimization is the third issue. Many existing technologies can be used to reduce emissions almost immediately at little cost.