Large language model reveals an increase in climate contrarian speech in the United States Congress

Contrarian voices on climate change have reached the highest levels of government in the United States: the US Congress has been a focal point for climate obstruction, playing an important role in impeding US climate action and stymieing global negotiations. We take a closer look at these voices by examining Congressional speeches from 1994 to 2023, a period containing important moments in the history of climate (in)action in the US. We contribute to the literature by 1) developing a scalable large language model (LLM) to accurately classify climate contrarianism in Congressional speech and 2) offering a systematic analysis of the specific contrarian claims in Congress. We demonstrate that an increasing proportion of speeches are critiquing the costs of climate solutions and Republicans are roughly 12 times more likely than Democrats to make contrarian claims. Statistical analysis further suggests that demographic factors and district-level fossil fuel employment predict claims making in floor speeches.