Climate change is becoming one of America’s most critical national security issues of the 21st century. Scientists are sounding an alarm that gets louder every year: The burning of fossil fuels releases more greenhouse gases into the atmosphere, strengthening the greenhouse effect and changing the Earth’s climate. There are many uncertainties, but they are about the effects and the rate of climate change, not its causes.

With the world continuing to burn fossil fuels at a reckless pace, the concentration of greenhouse gases in the atmosphere is the highest it has been in over 800,000 years. As a result, average global temperatures have already increased 1.3-degrees F over the last century, and without major reductions in emissions, we may be heading towards an additional 4- to 11-degrees F temperature rise by 2100.

The effects of this temperature change are severe. Climate change is usually presented as an environmental problem, but the consequences—and the consequences of the consequences—present real national security threats to the United States.

First, climate change generates new security risks around the world. Although climate change may not directly cause violent conflict, it acts as “an accelerant of instability” or a “threat multiplier.” That is, it makes conflict more likely, or intensifies conflict already underway. For example, climate change wreaked havoc on Mali, a poor, dry Saharan nation with an unstable government. As rivers dried up and agricultural production suffered, Al-Qaeda-linked militants capitalized on instability and overthrew the government in 2012. We cannot say that climate change has caused conflict in Mali, but it clearly multiplied the already existing threats.

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