Sajjad Azhar
Tehran / Islamabad
As Iran’s capital confronts a looming water crisis so severe that senior officials have discussed relocating parts of the city, scientists say the warning signs echo a catastrophe that unfolded thousands of years ago — the slow-motion collapse of the Indus Valley Civilization, once among the world’s most advanced urban societies.
Archaeologists and climate researchers now widely agree that the decline of the civilization — which stretched across what is now Pakistan and northwest India — was driven not by invading armies, but by a series of powerful, long-lasting droughts that reshaped river systems and crippled agriculture.
Recent research published in the journal Nature suggests that between 4,400 and 3,400 years ago, the region experienced repeated and severe drops in rainfall. Scientists pieced together ancient climate records from lakes, caves, marine sediments and plant remains. Their conclusion: as monsoon patterns weakened and major rivers shrank, great cities such as Mohenjo-Daro and Harappa were slowly abandoned. Populations dispersed into smaller rural settlements, searching for water and arable land.
Some droughts may have lasted more than a century.
That finding has also dealt a blow to the once-dominant “Aryan invasion” theory, promoted by 19th-century European scholars who argued that migrants from Central Asia destroyed the urban Indus world. Modern archaeology and genetics suggest instead that the culture declined gradually, shaped largely by environmental stress.
Today, the parallels feel uncomfortably close.
Pakistan’s average temperature has risen about 1.5 degrees Celsius over the past century. Its 13,000-plus glaciers — the source of up to 70 percent of the Indus River’s flow — are melting at an accelerating rate. Officials say more than 3,000 glacial lakes have formed, and dozens are at risk of bursting, threatening millions who live downstream.
“If current warming trends continue, Pakistan could lose half of its glaciers by the end of the century — and far more if temperatures climb higher,” said Dr. Fahad Saeed, a climate scientist whose work tracks the impact of rising heat on Himalayan ice. “Food security, water security — and national security — are all linked.”
Across the border in Iran, Tehran’s reservoirs now hold only a dwindling supply, prompting fresh anxiety over how long the metropolis of 15 million can remain viable in its current form. The crisis has revived stories etched on ancient rock carvings of King Darius I praying for rain during a devastating drought 2,500 years ago.
Scholars warn that the climate itself has long moved in cycles — and that South Asia may again be entering a period of monsoon instability similar to the one that humbled the Indus Valley Civilization. Some researchers believe the Gandhara Civilization, centered near today’s Peshawar, may also have been weakened by environmental stress before foreign invaders arrived.
That history now reads less like distant archaeology and more like a cautionary tale.
The Indus Valley Civilization once covered nearly a million square kilometers, home to perhaps a tenth of the world’s population. Its people built gridded streets, complex drainage systems and orderly neighborhoods that still astonish modern planners.
And then, almost silently, the water began to disappear.
Today the question facing Pakistan, Iran and their neighbors is whether they can adapt more quickly than their ancient predecessors — or whether climate change will again redraw the map of one of the world’s oldest cultural heartlands.
