Saturday, May 26, 2018

Maybe its not a drought

Editor, New Mexican

Stolen from the Albuquerque Journal article
 linked in the text
 Both the Santa Fe and Albuquerque newspapers have recently run stories about how New Mexico is in severe, persistent drought. To be sure, "severe drought" has plagued the state in 2011-12, 2013, and presently. Maybe there is a pattern here we want to avoid discussing.

Many if not most of the climate models for the 21st century suggest that climate change, in part driven by human industrial emissions, will result in progressive drying in the American Southwest. The reasons for drying include an expansion of the subtropical high, warming that increases evaporation and transpiration, and reduced snowpack. All of these will impact ground and surface water in New Mexico and put increasing stresses on natural systems and human agricultural and urban resources.

Drying in the Southwest is nothing new. Decade to century long drying has occurred several times in the last couple millennia, most pronounced during the Roman and Medieval periods. During the twentieth century, Elephant Butte Lake levels have oscillated between poverty and plenty in concert with the Pacific Decadal Oscillation. Anthropogenic climate forcing due to changes in greenhouse gas concentrations in the atmosphere is an overprint onto natural variability; it intensifies the chances of increased warming and drying on a century to millennial time frame.

The bottom line is that individuals, governments, and newspapers have to stop behaving as though we are in a transient drought with a return to "normal" and realize that more likely, we are going into another prolonged drying. How well we manage drying will depend on policy decisions we make if we wish to be proactive rather than suffer the consequences of whistling past the graveyard.

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