If global temperatures continue to rise, rainfall will increasingly become a beast of extremes: long dry spells here, dangerous floods there and in some places, intense water shortages. As early as 2025, the World Health Organization estimates that half of the world’s population will be living in water-stressed areas.
Although a shortage of clean drinking water is the most immediate threat to human health, water scarcity can have far-reaching consequences. Diminished flows in rivers and streams can increase concentration of harmful pollutants.
Researchers including Rosemary Knight and Scott Fendorf at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth) have shown that overtaxed aquifers in some places may become more vulnerable to contamination.
When waterways run dry, animals may seek out drinking water from places where people live, increasing the likelihood of contact between humans with wildlife and any disease-carrying insects they host.
Drought can also elevate risk of wildfires and dust storms that may lead to irritation of lungs and airways.
More directly, when people can’t get enough water for sanitation and handwashing, respiratory and gastrointestinal illnesses tend to spread more easily.
Food safety can be affected, too: When soils dry out and become compacted, it’s more likely that rain will run off the surface and carry contaminants to crops instead of soaking into the ground.
The team analyzed data collected through remote sensing and government surveys and developed computer simulations of hydrological processes under different scenarios. The results showed that, barring significant reductions in global greenhouse gas emission rates, rainfall in Jordan will decline by 30 percent and the occurrence of drought will triple by 2100.
“We don’t know just how bad those impacts of climate change will be or how large the population will grow,” said Gorelick, the Cyrus Fisher Tolman Professor at Stanford Earth. “But it appears to us that Jordan’s freshwater future is pretty grim.”