Using Twitter data, this study evaluates and maps climate change denialism across the United States. We estimate that 14.8% of Americans do not believe in climate change. This denialism highest in the central and southern U.S. However, it also persists in clusters within states where belief in climate change is high. Political affiliation was the strongest determinant, followed by level of education, COVID-19 vaccination rates, carbon intensity of the regional economy, and income. A coordinated social media network in the Twittersphere uses periodic events, such as cold weather and climate conferences, to sow disbelief about climate change and science in general. Donald Trump was the most influential, followed by conservative media outlets, and right-wing activists. As a form of knowledge vulnerability, this denialism renders communities unprepared to take steps to increase resilience. We recommend that social media companies flag accounts that spread climate misinformation and initiate targeted educational campaigns.