GLOBAL WARMING HAS FOCUSED concern on land and sky as soaring temperatures intensify hurricanes, droughts and wildfires. But another climate crisis is unfolding, underfoot and out of view.

Many of the aquifers that supply 90 percent of the nation’s water systems, and which have transformed vast stretches of America into some of the world’s most bountiful farmland, are being severely depleted. These declines are threatening irreversible harm to the American economy and society as a whole.

The New York Times conducted a months-long examination of groundwater depletion, interviewing more than 100 experts, traveling the country and creating a comprehensive database using millions of readings from monitoring sites. The investigation reveals how America’s life-giving resource is being exhausted in much of the country, and in many cases it won’t come back. Huge industrial farms and sprawling cities are draining aquifers that could take centuries or millenniums to replenish themselves if they recover at all.