The presidential debates, research on how a mega drought may have contributed to instability in Syria and the negotiations in Paris have brought a lot of attention recently to the idea of climate change as a national security threat. This is not a new idea, however, and it’s certainly not a partisan one. It’s something both our defense and intelligence communities have been worried about for a long time.

Why the worry? First of all, climate change is what the U.S. Department of Defense calls a “threat multiplier.” This means that it can make other security risks — food and water scarcity in strategically-significant nations, for example — a lot worse. This in turn can increase the likelihood of state failure and conflict, which the United States, will almost certainly be called upon to deal with. Whether it’s the possibility of greater instability in the Middle East or North Africa, increased tensions in the South China Sea, or a melting Arctic, climate change is introducing new risks into the security landscape. And as the de facto guarantors of international security, the United States will be expected to handle it.