The line between haves and have-nots in the 21st century may ultimately be drawn by reference to the most fundamentally important commodity on the planet – water.

More than gold or oil, arable land or technological advancements, the building block of continued human life, both individually and collectively, is clean drinking water. And perhaps the first country to face the consequences of running out of water, and the large-scale social, political and economic consequences of thirst, is Yemen.

Yemen is a country of over 20 million people that sits on the coast of the Arabian Peninsula just south of its larger neighbor, Saudi Arabia. It is a country plagued by war, burdened by refugees and internally displaced persons, without many of the functioning elements of government and civil society necessary to take on such an all-encompassing existential challenge as depleting its groundwater reserves.

Experts believe that within a decade, Yemen’s capital, Sana’a, could run out of water. The growing shortages in the provinces have reinforced tribal divisions within the country, leading to infighting, hoarding and profiteering. The imminent disappearance of water can be devastating to a Yemeni community, leaving desperate individuals – who lack the money to pay the “going rate” from the tanker trucks – to walk miles, and wait hours, to collect water from sources that may only be available irregularly.

Wealthy Yemeni with ready cash can buy clean water shipped across the country in guarded tanker trucks. The rest of population has only one option – wait for the rain to fall.

Is this a vision of what more and more of the world may face in the near future?

Will the wars of the future be started not as a scramble for oil or secure trading markets for exports or geopolitical higher ground but, rather, for the simple necessity of clean drinking water?

Regardless of one’s personal view on climate change, the reality of water shortages and droughts (whether originating from natural or man-made causes) is real enough. And any scarce resource will soon enough become a focus of short-term greed and long-term exploitation, as different constituencies scramble for their “fair share.”

To think that this is a regional issue, limited to a few desert countries in the Middle East, may be a tremendous mistake.

A four-year drought in Kenya has devastated large parts of that African country. Some have argued that the problems underlying the conflict in Darfur ultimately derive from ongoing droughts in Sudan. Further afield, reports from China indicate that many of their fastest-growing cities will cease to be self-sufficient for water in the next few years. Even Australia, like a number of other countries facing demographic and resource challenges, is considering large-scale projects involving the desalinization of seawater.

Few Americans think more about water and its effect on our economy and our lifestyles and our livelihood than Californians.

But what is the answer?

Desalinization is perhaps the most expensive way currently available of obtaining drinking water, and its ultimate effect on the marine environment is unknown. Changes in agricultural practices and food consumption patterns would require strong and coordinated governmental and nongovernmental action on a widespread basis.

Recent history has taught that we ignore the concerns and needs of others in the world at our own peril. To the extent that we ourselves have adequate access to sources of clean drinking water for the foreseeable future does not mean that we should be ambivalent about these questions. The impact of failed states on our security at home and our mutual interest in stability abroad is real, and should be a priority for us.

If the future lines of battle in many strategically important countries will be drawn between the “water-rich” and the “water-poor,” then we should be prepared now to address these concerns. The disparate impact of population growth in certain areas with declining resources can, with the passage of time, reach across the globe and impact us very directly.

We often are confronted with pleas from charities for aid to starving, drought-ridden countries, whether by way of celebrity Christmas records or fund-raising rock concerts or television appeals. But the reality of thirst as a driver for internecine and cross-border political and military struggle is potentially a much more profound challenge for us to face.

Perhaps the time to start thinking more seriously about this important resource, and prioritizing its continued availability in at-risk countries, is sooner than we would have thought.

The best way to win the “water wars” of the future may be not to have to fight them at all.