Nuclear Information and Resource Service (NIRS) is an anti-nuclear-energy advocacy group. NIRS was one of more than 600 co-signing organizations on a January 2019 open letter to Congress titled “Legislation to Address the Urgent Threat of Climate Change.” The signatories declared their support for new laws to bring about “100 percent decarbonization” of the transportation sector but denounced nuclear power as an example of “dirty energy” that should not be included in any legislation promoting the use of so-called “renewable energy.”
NIRS was one of more than 100 co-signatories on a November 2020 letter to the U.S. Senate that expressed opposition to S. 4897, the “American Nuclear Infrastructure Act of 2020.” The letter stated that nuclear power “amplifies and expands the dangers of climate change” and denounced it as an example of “false solutions to the climate crisis that perpetuate our reliance on dirty energy industries.” 
Nuclear power plants produce no carbon dioxide or other greenhouse gas emissions, and as of 2021 accounted for 20 percent of American electricity production—the largest source of zero carbon electricity in the United States.  An October 2018 proposal from The Nature Conservancy noted that zero-carbon nuclear plants produced 7.8 percent of total world energy output and recommended reducing carbon emissions by increasing nuclear capacity to 33 percent of total world energy output.