Climate Change and International Responses Increasing Challenges to US National Security Through 2040

"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.

Key Judgment 1:

Geopolitical tensions are likely to grow as countries increasingly argue about how to accelerate the reductions in net greenhouse gas emissions that will be needed to meet the Paris Agreement goals. Debate will center on who bears more responsibility to act and to pay—and how quickly—and countries will compete to control resources and dominate new technologies needed for the clean energy transition. Most countries will face difficult economic choices and probably will count on technological breakthroughs to rapidly reduce their net emissions later. China and India will play critical roles in determining the trajectory of temperature rise.

Key Judgment 2:

The increasing physical effects of climate change are likely to exacerbate cross-border geopolitical flashpoints as states take steps to secure their interests. The reduction in sea ice already is amplifying strategic competition in the Arctic over access to its natural resources. Elsewhere, as temperatures rise and more extreme effects manifest, there is a growing risk of conflict over water and migration, particularly after 2030, and an increasing chance that countries will unilaterally test and deploy large-scale solar geoengineering—creating a new area of disputes.

Key Judgment 3:

Scientific forecasts indicate that intensifying physical effects of climate change out to 2040 and beyond will be most acutely felt in developing countries, which we assess are also the least able to adapt to such changes. These physical effects will increase the potential for instability and possibly internal conflict in these countries, in some cases creating additional demands on US diplomatic, economic, humanitarian, and military resources. Despite geographic and financial resource advantages, the United States and partners face costly challenges that will become more difficult to manage without concerted effort to reduce emissions and cap warming.."
Climate change and national security