Early 21st Century Trends in Temperature and Precipitation in the Upper Rio Grande Basin, New Mexico and Colorado (AWRA Luncheon 9/10)
Sep 10, 2013
from 11:15 AM to 12:30 PM
|Where||O'Niell's Pub 4310 Central SE Albuquerque|
|Add event to calendar||
Changes in temperature and precipitation in the Upper Rio Grande (URG) basin of Colorado and New Mexico are projected to reduce stream flow in this snowfall-dominated basin. Data from 36 SNOTEL, COOP and HCN stations for 1971-2012 show that the current rate of temperature increase in mountain headwaters Tmin is faster than for the region as a whole, and faster than projected by regional climate models. Mountain subregions experienced the greatest rates of increase in Tmin in winter (0.36-1.08°C/decade) and spring (0.67-1.5°C/decade), with significant but smaller increasing trend (~0.5°C/decade) over the remaining months. Warming was greatest in the San Juan and Tusas Mountains, the two regions producing the majority of snowmelt runoff to the Rio Grande. Changes in mountain Tmax were minimal across all seasons. These trends appear to be robust to changes in Pacific Decadal Oscillation regime. Valley subregions experienced more equable changes in temperature, with increases in both Tmin and Tmax of approximately 0.3-0.5°C/decade in both winter and summer. Precipitation showed no long-term trend over 1971-2012. Contrary to climate model projections, the rate of mountain Tmin increase is larger in winter than summer. Mountain warming is occurring faster than suggested by region-wide and westwide temperature trends studies. If the observed trends continue, flow in the Rio Grande is likely to decrease, requiring adjustments in how river flows are managed to meet the future municipal, industrial, agricultural and ecological needs of valley communities.
Dr. Pinson is a climate science specialist and writer with the U.S. Army Corps of Engineers, Albuquerque District. Prior to joining the Corps of Engineers, Dr. Pinson taught geography and archaeology at UNM, CNM, and the University of Nevada, Reno.