human
When did the United States become the world’s largest emitter of greenhouse gases?
assistant
The United States became the world’s largest emitter of greenhouse gases in the early 1980s. The United States had been a relatively minor emitter of greenhouse gases until the late 1970s, when the use of fossil fuels began to increase rapidly. In the early 1980s, the U.S. economy experienced a major economic boom as a result of the oil shocks of the 1970s. This led to an increase in energy consumption and an increase in greenhouse gas emissions.