Water sustains life on our planet. And access to clean and safe water is foundational to society. So why has it only been in recent years that water has risen to the top of discussions of climate and security? Richard W. Spinrad, the Under Secretary of Commerce for Oceans and Atmosphere and NOAA Administrator, says that one of the biggest reasons is the major impact that climate-related changes in precipitation like droughts and extreme rainfall are having across the globe: “We’re starting to see things like we’ve never seen before. The nature of storms is changing: We saw five feet of rain fall in Hurricane Harvey. Five feet.”

The world has plenty of reasons to avoid conflict already. Yet attendees at the recently-concluded COP27 climate conference in Sharm el-Sheikh, Egypt were presented with another compelling argument: Warfare is bad for global warming. So much so, in fact, that Ukraine’s delegation to the conference organized a special session at the conference of parties on “War Related Emissions,” bringing along a tree trunk bearing scars from Russian shell fragments as tangible evidence.

Is water important in climate policy? It seems obvious. Water has a well-established link as the medium of most negative climate impacts. Yet when it comes to addressing the climate crisis, the answer depends very much on who you ask.

As climate change is increasingly recognized as a security issue, a parallel understanding is also developing. Traditional categories and approaches may not be the optimal way to address the threats posed by climate impacts.

The nation states and international institutions at the center of security discussions now are shifting their approach. For instance, the U.S. has affirmed and moved to institutionalize its commitment to address the national security implications of climate change under the Biden Administration. In doing so, it is joining an increasing number of other nation-states (the UK, France, Sweden, Germany and New Zealand) that have also developed institutional arrangements and plans for their national response to climate insecurity.

There’s a scene near the climax of Agatha Christie’s Murder on the Orient Express when Hercule Poirot starts to plot out the possible murderers. There’s Colonel Arbuthnot, who had opportunity and motive. There’s Mr. McQueen, suspicious in his transparent attempts to misdirect the detective. There’s even the haughty, toad-faced Princess Dragomiroff. Like practically everyone on the train, she had good reason to wish the evil Ratchett dead.

During the November COP27 climate talks in Egypt, Presidents Xi and Biden agreed to restart bilateral climate talks that would build on the clean energy and the green and climate-resilient agriculture priorities highlighted in the U.S.-China Climate Crisis Statement and the U.S.-China Glasgow Declaration. While details remain to be ironed out, the renewed dialogue could open up a new area of collaboration around greenhouse gas emissions from food production, targeting an oft-overlooked long-lived climate pollutant, nitrous oxide (N2O).