Surviving a warmer world: Global forecast is 'mostly dry'
Climate change is already being blamed for altered rainfall patterns and shrinking glaciers that provide water for drinking and agriculture. Part 1 of an occasional series.
SANTA FE, N.M.
It's a late March morning, and a light breeze tousles the tops of aspens and Ponderosa pines at Elk Cabin, one of the oldest spots in New Mexico for recording the depth of winter snow. Richard Armijo, a measuring stick in hand, is there to gauge this spring's snowpack.Skip to next paragraph
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The site, in the Sangre de Cristo Mountains, sits just upstream from two reservoirs that serve the city of Santa Fe. In late March, Elk Cabin should have a foot of snow on the ground, but it's nearly bare.
Like much of the West, New Mexico has endured a long drought.
According to the latest scientific evidence, such dry spells are likely to grow more severe – as they will around the world. Global warming, climate scientists say, is changing climates from the Himalayan Mountains to the Euphrates-Tigris River Basin. Patterns of rain and snowfall are shifting significantly.
The question now becomes: How will nations and individuals adapt as Earth's climate warms? Glaciers from the Andes to the Alps are shrinking at an accelerating pace. Countries are already haggling over river rights. From 400 million to as many as 3.2 billion people face serious water shortages over the next 20 to 50 years. New Mexico, an already dry region that is getting drier, is on the front lines.
Mr. Armijo, a snow surveyor for the US Department of Agriculture, knows something is going on. Like much of the American West, the state has been in the grip of drought for years.
"We've set record lows for snowpack a couple of times in the last five or six years," he says. "For the most part, the snowpack's gone. In the last three to four weeks, we've experienced some really warm temperatures."
In early February, the UN released a report on the science behind global warming. In it, researchers expressed "very high confidence" that greenhouse-gas emissions – mostly carbon dioxide from burning coal, oil, and natural gas – have been warming the climate.
If these emissions continue to grow at their current rates, the report estimates, global average temperatures could top their 1980-2000 average by 2.3 to 4.1 degrees C. (4.1 to 7.4 degrees F.) by the end of the century. Among the warming's effects: Arid regions will dry out further. And some of the water that they do receive will come in the wrong form (rain instead of snow) or at the wrong time.
On April 6 the UN-sponsored Intergovernmental Panel on Climate Change (IPCC) will release the second of its four major global-warming reports due this year. The focus: the challenges that vulnerable regions are likely to face and their options for adapting.
The new IPCC report is expected to pay close attention to warming's impact on water resources – and for good reason, says James McCarthy, professor of biological oceanography at Harvard University and past co-chairman of the 2001 IPCC working group. In the last five years, scientists have seen "a consistent record" showing a pattern of droughts alternating with strong downpours "with less opportunity for that moisture to be absorbed or retained," Dr. McCarthy says.
A city slakes its thirst
How will humans cope with a drier climate? The city of Albuquerque has shown how much water can be saved through a concerted effort – if resources are available. But its experience also highlights the complex demands made on water resources.
The state's major river, the Rio Grande, cuts through Albuquerque. But it's only a dry riverbed part of the year. The city draws virtually all of its water from an underground aquifer, says John Stomp III, water resources manager for the city. By some accounts, Albuquerque once was thought to be sitting atop an aquifer with enough fresh water to fill Lake Michigan.