Over 4,000 years ago, the city of Umma declared war on its neighbour the city of Lagash, in modern-day Iraq, near the confluence of the Tigris and Euphrates Rivers. This conflict is known as one of the earliest organised battles ever fought.

Why should we care? This war was also the first recorded “water war”. The conflict was sparked by the diversion of water to canals by the king of Lagash, depriving Umma of fresh water. More recently, the border tensions between Kyrgyzstan and Tajikistan, which flared again last month, are also related to clashes over the management of transboundary water resources.

As Europe is going through its worst drought in at least 500 years, this story should be a wake-up call. Climate change is upon us. Resources such as water that were once abundant are now scarce. When people are thirsty and hungry, violence is never far away. The spectre of water wars looms, either locally between different users, such as farmers, industries and citizens, or on a national level, between countries.