Waters that cross international political borders can drive the countries that share them to conflict—or encourage cooperation between them. Indeed, since the 1940s, overall trends point to a tendency for countries to cooperate over shared water resources, which stands in stark contrast to media portrayals of “water wars.”

Yet instances of conflict over water have increased slightly since 2000. Why? Most of them are fueled by water quantity disputes or the unilateral development of dams or other infrastructure. Institutions often play a key role in facilitating cooperation (and reducing conflict) over shared waters, but their growth and adoption have slowed over the last two to three decades.

By 2050, two-thirds of the population will face some form of water stress. As a fundamental part of life, water—or a lack of it—influences other parts of life, including conflict. In fact, as author Marcus King notes in his new book, Weaponizing Water: Water Stress and Islamic Extremist Violence in Africa and the Middle East, there is a “correlation between the spheres of influence of violent extremist organizations (VEOs) and the driest lands or areas of sparse vegetation in some of the most arid regions on earth.”

The Horn of Africa now faces an unprecedented drought, with conditions not seen in the last 40 years. The implications of this looming catastrophe reach beyond the most recent severe drought periods in the region, which occurred in 2010 and 2011 and again in 2016 and 2017.

As of November 2022, over 36 million people in the Horn were affected by drought, including 24.1 million in Ethiopia, 7.8 million in Somalia, and 4.2 million in Kenya. More than 20 million children in Djibouti, Ethiopia, Kenya, and Somalia need immediate water and food assistance. In addition, nearly 1 million pregnant and lactating women are acutely malnourished. Since mid-2021, more than 9.5 million livestock have perished in the region due to a lack of water, starvation, and disease.

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.

Climate impacts are growing more frequent and severe as global temperatures rise. Weather-related disasters have seen a five-fold increase over the past half-century. In many cases, these calamities are already testing the adaptation capabilities of vulnerable communities across the world. If emissions follow the trajectory set by current country targets, the chance of temporarily overshooting the 1.5 °C target in the next five years is 48 percent.

This failure would have implications for the global economy and international security. Yet despite the fact that climate change shapes geopolitics, climate risk itself has rarely been featured in international geopolitics and diplomacy.