SANA, YemenArriving in Yemen last week, I had an experience I’d never had before. I drove from the airport into Sana, the capital, on the main thoroughfare, through a raging torrent of water. I was staying in the old city, a United Nations World Heritage site, which is accessed primarily by an ancient, moat-like road, known as the Sailah. It used to be made of dirt, shrub and pepper trees, which for generations absorbed water in the rainy season, although in downpours it would still flood. But, in 1995, at Yemen’s request, the United States paid to have it paved. Because Yemenis have largely deforested all the mountains around Sana, the lack of trees, vegetation and topsoil means the rainwater now rushes off the mountains, enters the paved city and finds its way to the paved Sailah, turning the road into a rushing aqueduct. Our S.U.V. eventually made it upstream to our hotel, giving a whole new meaning to the expression “we sailed into town.”The other day, it hailed in Sana, piling up in some spots like a winter snow to a degree no one could remember. Meanwhile, up north, the most violent rainstorms in 25 years in Saudi Arabia just killed 13 Saudis in flooding and had Saudi television airing “footage of people clinging to trees and cars trapped by water,” the BBC reported.

It is impossible to say if these more powerful storms are the result of global warming, which is expected to make the hots hotter, the dries drier and the wets wetter in certain areas. What is not in doubt is that something is changing. Yemeni farmers traditionally divided their growing season into 13-day increments for each aspect of planting and harvesting. “That is how dependable the summer rains were — but not anymore,” said Abdul Rahman al-Eryani, Yemen’s former minister of water and environment. They have become both more erratic and more violent.

What also is not in doubt is that these weather changes are adding to the stress on frail infrastructure across the Arab world. This, combined with continued high population growth, is helping to fuel the Arab uprisings against the old Arab regimes and adding to the challenges for the new ones. For instance, the water table here in Sana has fallen so low from overdrilling, and has dried out the bedrock sandstone so much that it appears to be triggering geological faults, said Eryani. Sana just built a new airport terminal, but, while it was under construction, a fault opened underneath it, extending for miles and requiring an injection of concrete to keep it stable.

Most of the old generation of Arab leaders never gave much thought to natural capital: the forests, shrubs and ecosystems that naturally store water, prevent runoff, flooding and silting. The new generation will have to be environmentalists, otherwise their new politics will be overwhelmed by environmental stresses.

Yemen is the leading edge of this trend. In 2009, Eryani encouraged then-President Ali Abdullah Saleh to name the endangered Arabian leopard as Yemen’s “national animal,” in hopes of preventing its extinction and promoting more environmental awareness. (Where the wildlife thrives, the people usually thrive.)“The Arabian leopard is at the top of the food chain here,” explained Eryani, “so if we can keep it alive in the wild, it is a strong indicator that the ecosystem is still intact.” As the biggest predator, the Arabian leopard can survive only if the antelope, the rabbits, the partridges, gazelles, ibex and hyrax that it feeds on also survive. Those animals, in turn, need a healthy ecosystem of springs, shrub lands, topsoil and forests. Not surprisingly, since all of those are disappearing, so, too, are the leopards.

In 2009, an American teacher in Yemen, David Stanton, set up a foundation here to protect endangered wildlife, focusing on the leopards. We met the other day outside the leopard zone at the Sana Zoo to discuss their future, while one of these sleek animals lounged on a shelf in his cage — waiting for his daily diet of donkey meat.

“Generally speaking, the Arabian Peninsula is drying,” said Stanton, and while the Arabian leopard can roam wide areas for a long time without water, their prey cannot. “So when you destroy the habitat of the prey, you destroy the habitat of the predators.”Stanton started his work before the democracy revolution here in 2011, and back then, he recalled, “people would come to me and say: ‘Why are you protecting leopards when we have leopards in the government?’ ”Of course, they were right. Arab dictators were at the top of the food chain in their countries — the ultimate predators. Eventually, though, they and their cronies and families ate so much themselves — while also despoiling their natural capital — that there was too little left for the rest of their burgeoning populations, and their people revolted.

The governments experiencing Arab awakenings, though, will never sustainably rebuild their countries’ human capital if they don’t also rebuild their natural capital. If you visit Yemen in five years and hear that the Arabian leopards are extinct, you’ll know the revolution here failed. But if you hear that the leopard population is on the rise again, there is a high likelihood that its people will be as well. Watch the leopards.