National Intelligence Estimate – Climate Change and International Responses Increasing Challenges to US National Security Through 2040. October 21, 2021. “We assess that climate change will increasingly exacerbate risks to US national security interests as the physical impacts increase and geopolitical tensions mount about how to respond to the challenge. Global momentum is growing for more ambitious greenhouse gas emissions reductions, but current policies and pledges are insufficient to meet the Paris Agreement goals. Countries are arguing about who should act sooner and competing to control the growing clean energy transition. Intensifying physical effects will exacerbate geopolitical flashpoints, particularly after 2030, and key countries and regions will face increasing risks of instability and need for humanitarian assistance.

• As a baseline, the IC uses the US Federal Scientific community’s high confidence in global projections of temperature increase and moderate confidence in regional projections of the intensity of extreme weather and other effects during the next two decades. Global temperatures have increased 1.1 ̊C since pre-industrial times and most likely will add 0.4 ̊C to reach 1.5 ̊C around 2030.
• The IC has moderate confidence in the pace of decarbonization and low to moderate confidence in how physical climate impacts will affect US national security interests and the nature of geopolitical conflict, given the complex dimensions of human and state decisionmaking…”