Rebound effects differ in scale depending on the type of energy efficiency improvements, and in which part of the economy they occur. Over 100 academic studies have examined the empirical evidence, conducted modeling inquiries, and otherwise tested the scale of rebound effects. While there is much more work to be done to determine the precise scale and impact of rebound effects in different circumstances, the conclusion is that rebound effects are significant and cannot be ignored in energy and climate analysis and policymaking.