Artificial intelligence (AI) technologies are increasingly viewed as both a potential driver of environmental sustainability and a contributor to global energy demand. Yet little is known about how the public interprets these dual narratives. We conducted a pre-registered online experiment (N = 2142) on a representative sample of the United States to examine how framing the environmental impacts of AI—as positive or negative—affects beliefs, policy preferences, and behavioral intentions. Positive messaging led to greater optimism about AI’s environmental impact, lower support for regulation, increased support for government subsidies of AI-enabled technology adoption, and increased consumer preferences for AI-enabled appliances. Negative messaging increased support for regulation and decreased support for government subsidies. Consistent with previous evidence, the messenger (scientist vs journalist) had minimal impact. Our findings highlight the power of environmental framing in shaping public narratives around AI, with implications for science communication, sustainability governance, and technology acceptance.