Warming to Have Major Impacts on Western Water

There was a plethora of climate change related articles that appeared in the July to August timeframe. Sample headlines included:
  • Ten key indicators show global warming "undeniable"
  • Climate change launches new geologic epoch
  • Study quantifies potential impacts of climate change
  • Climate change threatens agricultural water
  • Global warming and the vanishing tundra
  • Risk of water scarcity increasing for 1,100 U.S. counties [due to global warming]
  • Sandia Labs pinpoints global warming risk and costs
In regard to the first headline and citing a comprehensive review of the last decade of climate data, scientists have determined that global warming is undeniable. The 10 key planet-wide indicators of a warming climate identified are: higher temperatures over land, higher temperatures over oceans, higher ocean heat content, higher near-surface air temperatures, higher humidity, higher sea surface temperatures, higher sea levels, less sea ice, less snow cover, and shrinking glaciers. Related to these indicators, the National Academy of Sciences has determined that the world has entered a new geologic epoch.
This epoch, called the Anthropocene, is one in which human activities will largely determine the planet's evolution. Rising carbon dioxide emissions from the burning of fossil fuels have triggered this epoch, which could include profound changes in rainfall, crop yields, wildfires, and sea levels. The scientists say atmospheric concentration of CO2 has risen about 35% since 1750 and is now at about 390 parts per million, the highest level in at least 800,000 years. Depending on emission rates, they estimate those levels could double or nearly triple by the end of the century. According to the study, the Colorado River Basin could see a 5 to 10 percent decrease in rainfall, 6 percent less water in the river system for every 1.8-degree increase in temperature, and three times as much land devoured by wildfires. 
In another study for the Natural Resources Defense Council (NRDC) it was found that Colorado is at risk of having enough water to sustain agricultural needs. Warming temperatures will also result in a dramatic decline in tundra as tree lines climb higher and shrubs encroach on alpine meadows. In addition, global warming has already quickened the runoff cycle in the West, as runoff peaks up to two or three weeks earlier than just a few decades ago. The changes could have serious consequences for wildlife. As water becomes less available, there are fewer flowering plants and less food for animals. That could affect all wildlife and [pollinating] insect populations.
The NRDC also concluded that one out of three U.S. counties is facing a greater risk of water shortages by mid-century due to global warming. For 412 of these counties the risk of water shortages will be "extremely high," a 14-fold increase from previous estimates. Statewide, 27 of the 64 counties have high to extreme risk of water shortages. In the Dolores/San Juan River Basin, Montezuma and Montrose counties were identified as facing high to extreme water shortfalls. "This analysis shows climate change will take a serious toll on water supplies throughout the country in the coming decades,” said Dan Lashof, director of the Climate Center at NRDC. "Water shortages can strangle economic development and agricultural production and affected communities." "As a result," he said, "cities and states will bear real and significant costs if Congress fails to take the steps necessary to slow down and reverse the warming trend."
Of all the current and future impacts of climate change, threats to water resources may be the most painful—especially in the West. In the Southwest, water sustainability is at extreme risk. The Colorado Statewide Needs Assessment Report identifies a statewide shortfall of 500,000 acre feet and is expected to reach about 2.5 million acre feet by 2050--double the demand in 2008. In a study by Western Resource Advocate’s water-program director, Bart Miller, indicated "Of all the implications of a hotter climate, the water implications are the most dramatic or long-term.” It is the uncertainty of the range of consequences associated with climate change that validates the need to act proactively and protectively.