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Tuesday, October 23, 2007
Warming Could Be Costly to State
By John Fleck
Copyright © 2007 Albuquerque Journal; Journal Staff Writer
Diminishing water supplies as a result of global warming could cost New Mexico's economy hundreds of millions of dollars a year over the next century, according to a new study.
The study, to be unveiled at a news conference this morning in Albuquerque, found that an already arid New Mexico is "highly vulnerable" to climate change.
The average flow in the Rio Grande could drop by one-fourth over the next 75 years in response to climate change. With water supplies already stretched to the limit and the population growing, the state's economy, especially agriculture and recreation, could suffer, the study's authors found.
Riverside ecosystems are also likely to suffer.
The study's results are important for the state's water resources planners as well as the public to understand, said University of New Mexico civil engineering professor Julie Coonrod, one of its authors.
The report lays out a scenario of increasing conflict over New Mexico water. Agriculture currently uses the lion's share of the state's water resources but makes up a relatively small part of the state's total economy.
Currently, the state uses all of its share of the Rio Grande. Water shortages could slash agricultural income in the state as much as 20 percent, according to the study, and water-related recreation 30 percent. Cities could see more modest economic problems associated with increased costs for water as it gets more scarce.
The study's population numbers were based on projections by UNM's Bureau of Business and Economic Research.
The study by Coonrod and New Mexico State University economist Brian Hurd is the latest to point to declining water supplies in the Southwest as a result of a changing climate.
Most studies have focused on the Colorado River, the main water supply artery for much of the southwestern United States. The new work by Hurd and Coonrod is the most detailed study of the potential effect on the Rio Grande.
"The results are not surprising," Coonrod said in an interview Monday.
Most climate scientists believe tailpipe and factory stack emissions of greenhouse gases are warming Earth's climate. The most important effects, according to scientists, will not be the warming itself but the related changes in things like water supply.
Hurd and Coonrod used simulations of Earth's climate over the next century done for the Intergovernmental Panel on Climate Change, an international body of scientists studying the problem.
The simulations show a great deal of uncertainty about whether rain and snow will go up or down in New Mexico. But all the simulations agree that temperatures will rise.
"We do know that temperatures will go higher," said Martin Hoerling, a researcher at the federal government's Earth System Research Laboratory in Boulder, Colo.
That means more evaporation and less water in the rivers as a result, Coonrod said.
A similar study by Hoerling on the effect of climate change on the Colorado River showed the potential for dramatic reductions in the river's flow.
Because of those uncertainties, Hurd and Coonrod did a "what-if exercise," testing the effect of rising temperatures if rain and snow amounts go up, go down or stay similar to today.
The importance, Coonrod said, was not to try to predict the future, but rather to give policymakers and the public a sense of the different possibilities.
In each case wet, medium or dry the Rio Grande shrank because temperatures and therefore evaporation increase in each case. By 2080, they found, the wettest future scenario showed an 8 percent drop in the Rio Grande. The worst-case scenario showed a 29 percent drop. The middle scenario showed average Rio Grande flows dropping 23 percent.
The study was funded by the William and Flora Hewlett Foundation, a philanthropy that supports environmental causes.