How might climate change affect New Mexico?

By Mona Blaber

Every study released lately seems to have worse news about climate change, but it’s hard to translate the figures and statistics into any kind of idea of how life will change in New Mexico, or any region, in the coming decades. I asked University of New Mexico Earth and Planetary Sciences professor David Gutzler, who has researched climate variability in the West, about what these predictions mean for us.

Question: In October, a National Center for Atmospheric Research study predicted worse-than-Dust Bowl droughts, unprecedented drought, by the 2060s and earlier in the Southwest (and many other regions), even under moderate emissions scenarios. Does that study seem in line with research you’ve done?
Gutzler: Yes indeed. Tessia Robbins, one of our star undergrads at UNM, and I published a paper last year on projected droughts in the western US. Consistent with Aiguo’s (NCAR scientist Aiguo Dai) research, we find that the climate projections generated using a moderate greenhouse-gas-concentration scenario put the SW into a temperature regime outside the historical (20th century) range of variability by the latter half of this century. That rate of temperature increase drives Palmer Drought Index values into the “severe drought” category as the new climatic normal across the Southwest, by increasing evaporation off the surface.

Q: I hear about Dust Bowl conditions, and much of New Mexico and Texas is currently in extreme drought. Could conditions for farmers here be similar to the Dust Bowl in the next few decades? What changes can they expect?
A: Meteorological conditions are projected to trend toward those seen in the 1930s, or the 1950s in AZ and NM. However we need to be careful with terms like “Dust Bowl,” because land-management practices contributed substantially to that terrible event. As a society we should anticipate the high likelihood of much warmer temperatures, combined with decadal episodes of reduced precipitation, and make sure that we don’t repeat the land-management mistakes of the past.

Q: How would these drought conditions affect urban New Mexico residents?
A: Urban residents around here in the 20th century were buffered from drought because cities largely (or completely) pumped groundwater for municipal usage. Our cities are now more vulnerable to drought, in three ways: (1) we know that in many places groundwater has been considerably depleted, so our buffer has been mined; (2) cities in the Southwest have many more people ... the huge growth in urban population took place largely during several decades of anomalously high-precip years in the late 20th century; (3) as noted above, climate is trending toward warmer temperatures and more severe drought, making surface-water supplies more problematic right at the time when cities such as Albuquerque and Santa Fe are moving (at great expense) toward surface-water consumption. Note that only the last of the three reasons for increased water-supply vulnerability cited here is directly climate-related! Climate change is simply amplifying the increased vulnerability to water shortage that exists here anyway.

Q: We are still breathing smoke from the wildfire that started in Arizona, and the winds this spring seemed especially heavy and constant. Can we expect more and more of these conditions as the years pass?
A: Yes, increased wildfire activity is among the more confident projections we can make. The spring season, in particular—that’s wildfire season here, as everyone now realizes if they didn’t know it before this year—exhibits sharply rising temperatures and decreasing soil moisture in the Southwest. That’s in the data record now, not just a hypothetical projection from a model. Coming at the end of a century of active fire suppression that increased forest fuel density, these conditions are conducive to explosive fire this time of year.

Q: What can we do to prepare? What can we do to prevent? Or do you think it’s too late to stop warming, and we should concentrate on adapting?
A: Why set up a choice between preparation and prevention? Aren’t we smart enough to consider both?

One big difference between preparation and prevention (in climate research jargon, we call these approaches “adaptation” and “mitigation,” respectively) is that many potential aspects of adaptation can take place at the local scale, such as the measures adopted recently by the city of Chicago. Costs and benefits are easier to assess at the local level. That’s why the Clean Air Act applied to local air pollution works effectively—citizens can make a direct connection between whatever costs and hassles they incur, and the resulting improvement in local air quality.

Effective mitigation of greenhouse gas emissions must be coordinated internationally, and politically that’s much more difficult to implement. As we’ve seen, international mitigation efforts such as the Kyoto Protocol have so far failed completely, and discussion of a successor policy at the international level is paralyzed because nobody wants to be the first to implement a meaningful emissions reduction strategy. The argument for going first has to be based on the opportunity to become a leader in development of new energy sources. The New Mexico Environmental Improvement Board approved a pair of state policies last year based on that argument. It’s obviously controversial. The new administration in Santa Fe is working to overturn the policies.

To see a revealing map on how the Palmer Drought Index averages for the West using actual figures through 2007 and projections for a mid-range emissions scenario, see page 8 of the Rio Grande Sierran July-August-September 2011 issue.