Increasing evidence suggests that climate change poses direct and indirect threats to national and human security. However, the degree to which such knowledge of the risks informs decision-making remains poorly understood for key security communities, including the U.S. Department of Defense. Here, through document analysis and interviews with climate security researchers and practitioners from the U.S. military community, we evaluate perceptions about and the degree to which (i) these individuals believe climate change is a threat to U.S. national security interests, and (ii) the U.S. Department of Defense integrates climate security science into its decision-making. Our research suggests a complex answer. Public statements and reports indicate U.S. Department of Defense leadership considers climate change a security threat of strategic importance, and most researchers interviewed believe the U.S. Department of Defense prioritizes climate security as a near-term threat. However, evidence of climate security threats is only selectively integrated into planning and decision-making. Interviews suggest several barriers and enablers to evidence-based decision-making within the U.S. Department of Defense. Barriers include mixed beliefs in the near-term urgency of the threat, changing political environments, and insufficient co-production of actionable science across the levels of war, including issues of data collection, sharing, and analysis. Enablers include increased awareness after climate-related impacts, strong leadership support, and knowledge transfer and convening forums. Improved insight into the production and use of climate security knowledge is crucial for the task of safeguarding human and national security in a changing climate.

越来越多的证据表明，气候变化对国家和人类安全构成直接和间接威胁。然而，包括美国国防部在内的主要安全团体对这种风险知识对决策的影响程度仍然知之甚少。在这里，通过文件分析和对来自美国军事界的气候安全研究人员和从业人员的采访，我们评估了 (i) 这些人认为气候变化对美国国家安全利益构成威胁的看法和程度，以及 (ii)美国国防部将气候安全科学纳入其决策。我们的研究提出了一个复杂的答案。公开声明和报告表明美国 国防部领导层将气候变化视为具有战略重要性的安全威胁，接受采访的大多数研究人员认为，美国国防部将气候安全视为近期威胁。然而，气候安全威胁的证据只是有选择地纳入规划和决策。访谈表明，美国国防部内基于证据的决策存在若干障碍和推动因素。障碍包括对威胁的近期紧迫性的混合信念、不断变化的政治环境以及跨战争级别的可操作科学的合作不足，包括数据收集、共享和分析问题。促成因素包括在气候相关影响后提高认识、强有力的领导支持以及知识转移和召开论坛。