Drought has engulfed large swaths of the country, threatening parts of the nation's food and power supply. And it's getting worse. More than 80 percent of the continental U.S. is experiencing unusually dry conditions or full-on drought, which is the largest proportion since the National Oceanic and Atmospheric Administration began tracking 20 years ago. Winter is expected to intensify and spread the dry conditions, killing crops and increasing fire risks in regions that don't usually face such dangers, NOAA says. That could spell trouble for electricity in states such as California, Arizona and Nevada, depleting water supplies needed to cool power plants and reducing the flow to hydroelectric dams on waterways like the Colorado River. Of particular concern is the Mississippi River, where record-low water levels are making it hard to move cargo by barges, which is vital for transporting crude oil , corn, soybeans and other essentials. The developing drought across the Mississippi Basin is also allowing salt water to enter from the Gulf of Mexico, which could contaminate drinking water. California and the West are faring no better. The ongoing megadrought is expected to worsen, with no relief for the dangerously depleted Colorado River or the Southwest reservoirs of Lake Mead and Lake Powell. (Farther north, the Pacific Northwest and the Great Lakes region are actually expected to sustain heavier winter precipitation than normal.) The 22-year megadrought in the West has deepened so much that it's now considered the driest in at least 1,200 years. Authors of a recent study in the journal Nature Climate Change found that 42 percent of the drought is attributable to human-caused climate change, confirming experts' worst-case prediction for the current level of global warming. Meteorologists are also attributing the dry forecast to a third straight winter of La Niña, a complex weather pattern where strong trade winds churn colder water to the surface of the Pacific Ocean and push the jet stream north, which has only happened a few times in the last half-century. As the planet continues to warm, rare weather events like megadroughts are becoming increasingly common, along with 1,000-year floods and record-smashing heat waves. Scientists warn that unless the world dramatically reduces its carbon emissions, extreme weather — and the toll it takes — will become the norm.
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