Lobbying is considered to be an important factor in the success or failure of climate change legislation. This paper provides an estimate of lobbying expenditures related to climate change legislation in the U.S. Congress from 2000 to 2016. During this time period, over $2 billion was spent on this activity, constituting 3.9% of total lobbying expenditures. Major sectors involved in lobbying were fossil fuel and transportation corporations, utilities, and affiliated trade associations. Expenditures by these sectors dwarf those of environmental organizations and renewable energy corporations. Levels of expenditures on lobbying appear to be related to the introduction and probability of passage of significant climate legislation. Future research should focus on tying particular positions on climate legislation and lobbying expenditures at the corporate level.