Southwest Groundwater Disappearing at 'Shocking' Rate
U.S. Bureau of Reclamation
A ring of light-colored rock shows how much the water level has dropped at Nevada's Lake Mead.
John Hyde/Design Pics/Corbis
The effects of global warming are frequently projected decades into the future, but two recent reports -- one from theU.S. Global Change Research Program
and the otherfrom the U.N.
-- put into sharp focus visible consequences of our warming planet. An increase in temperature, extreme weather, loss of ice and rising sea level are just a few of changes we can measure right now. Let's take a look at some of the most concerning trends.BLOG: War Of The Words: Climate Change Or Global Warming?
Glaciers are shrinking worldwide and permafrost is thawing in high-latitude and high-elevation areas, reports this year's Fifth Assessment Report from the Intergovernmental Panel on Climate Change.BLOG: Dire Outlook For Climate Impacts, New Report Says
Only a few extinctions are attributed to climate change, reports the IPCC, but climate change that occurred much more slowly, over millions of years, caused major ecosystem shifts and species extinctions. Land and sea animals are changing their geographic ranges and migratory patterns due to climate change.NEWS: Climate Change: Why Haven't We Done More?
Sea level around the world has increased by about 8 inches since 1880, reports the 2014 National Climate Assessment, which projects a 1 to 4 foot rise by the end of the century.PHOTOS: Craziest Environmental Ideas (That Could Work)
Massimo Brega/The Lighthouse//Vi/Visuals Unlimited/Corbis
Excess CO2 is dissolving in the ocean and decreasing the pH of seawater. The ocean is about 30 percent more acidic than it was in pre-industrial times. More acidity in the oceans makes it harder for animals to form calcium carbonate shells and skeletons and erodes coral reefs.11 Health Threats from Climate Change
The probability of a Sandy-like storm deluging New York, New Jersey and other parts of the East Coast has nearly doubled compared to 1950, according to the American Meteorological Society. Even weaker storms will be more damaging now than they were 10 years ago because of rising sea levels. Superstorm Sandy cost the nation $65 billion, according to the 2014 National Climate Assessment, and 2012's Hurricane Isaac cost $2.3 billion.
The global sea level rises along with the temperature for two major reasons. For one, heat causes water to expand, which causes the existing water to take up more space and encroach on the coast. At the same time, ice at the poles and in glaciers melts and increases the amount of water in the oceans.PHOTOS: Melting Glaciers
Across the United States, heavy downpours are on the rise, especially in the Northeast and Midwest. Increases in extreme precipitation are expected for all U.S. regions, reports the 2014 National Climate Assessment.NEWS: Shrinking Greenland Glacier Smashes Speed Record
Ted Soqui/Ted Soqui Photography/Corbis
The most recent IPCC report states with "very high confidence" that current climate-related extremes like heat waves, droughts, floods, cyclones and wildfires are showing that countries around the world, at all development levels, are significantly unprepared. The American Meteorological Society estimates that approximately 35 percent of the extreme heat in the eastern United States between March and May 2012 resulted from human activities' effects on climate. The AMS warned that deadly heat waves will become four times more likely in the north-central and northeastern United States as the planet continues to warm.NASA: Global Warming Goes On
As the Southwest's drought has worsened in the last decade, making surface water scarce, millions of people are drawing more heavily on underground water supplies. The water is coming out faster than it's being replenished, a new study finds.
Between December 2004 and November 2013, more than 75 percent of the water lost in the Colorado River Basin was from groundwater, according to the study. The region has been in a drought since 2000, according to the U.S. Drought Monitor.
The results show that groundwater is already being used to fill the gap between the demands of the region's millions of residents and farmers, and the available surface water supply, the researchers said. [Dry and Drying: See Images of Droughta]
"We found a surprisingly high and long-term reliance on groundwater," study co-author Jay Famiglietti, senior water cycle scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.
For example, the amount of land irrigated by groundwater increased since the study began in December 2004, the researchers reported July 24 in the journal Geophysical Research Letters.
The study offers a bird's-eye view of groundwater in the Colorado River Basin, one of the most heavily used and closely watched water resources in the West. More than 40 million people rely on Colorado River water in the United States alone (water is also allocated to Mexico), the U.S. Geologic Survey estimates.
"We thought the picture could be pretty bad, but this is shocking," lead study author Stephanie Castle, a water resource specialist at the University of California, Irvine, said in a statement.
The Colorado River Basin stretches across seven states: from Wyoming across Colorado, Utah, Arizona, New Mexico, Nevada and California. Its groundwater is stored in underground aquifers and is sucked from the ground by wells. If water is removed from an aquifer faster than it can be replaced, eventually the wells will go dry.
Castle and her co-authors tracked groundwater loss in the basin with NASA's twin GRACE satellites (for Gravity Recovery and Climate Experiment). The satellites circle the Earth, monitoring the slight changes in Earth's gravity from increases or decreases in water. More water means more mass, which strengthens the pull of gravity on the satellites. (The satellites also track ice — their original mission was to monitor the planet's polar ice sheets and melting glaciers.)
Since December 2004, the basin of the Colorado River lost nearly 53 million acre feet (65 cubic kilometers) of freshwater, almost double the volume of the region's largest reservoir, Nevada's Lake Mead, the researchers reported. About 75 percent of the total — about 41 million acre feet (50 cubic km) — came from groundwater, the study found.
"We don't know exactly how much groundwater we have left, so we don't know when we're going to run out," Castle said. "This is a lot of water to lose."
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