Megadroughts, defined as droughts far more severe than anything we have experienced in the 20th century, have occurred numerous times across the Southwest. Are we due for another? As outlined in Jonathan Overpeck’s October post “What’s Ahead for the Climate of the Southwest?” changes in drought and aridity are forthcoming. Warmer regional and global temperatures are driving more evaporation and shifting the position of winter storm systems away from the Southwest. (Read More)

Author: Laura Marshall

It’s become a regular thing to turn on the news during the hot months of the year, and see images of wind-whipped flames devouring a California subdivision or a forested mountainside. In the last decade, fires in the West have burned much larger areas than previously. This phenomenon appears to be linked to the record warmth of the past decade, as well as with forest management choices. (Read More)

 Now that we (hopefully) have a better understanding of how climate models make long-term, generalized projections, can we use them to model our monsoon to figure out how it might be different under global climate change?  The answer is yes and no, and that has to do with scale. To understand that, we first need to consider how the monsoon works. (Read More)

Figure 1: The upper-level Bermuda High extending to the west in July, when our monsoon begins. The red colors are higher pressures; the center of the Bermuda High is marked by an 'H'. This image is from the National Weather Service. 

If you live in the Southwest, no doubt you know a little bit about our weather. It's interesting here. You likely know we have a monsoon during the summer, with awesome thunderstorms and flash floods, and our wettest winters and biggest floods happen when there's an El Niño event. We've also been hearing a lot about global climate change - and there's already a lot of evidence that it's happening here now. One big question is: how will our monsoon change in the future? (Read More)

Recently, a colleague (Brad Udall, University of Colorado) and I wrote a short overview of climate change in the West—based on peer-reviewed literature—that appeared in the journal Science (Overpeck and Udall, 2010). The big story is really in the Southwest. What follows here is a summary of our findings. (read more)

After reading a climate modeling paper in the journal Nature that discusses the speed of warming in different ecosystems, I wanted to hear how plants were moving in response to a changing climate from someone with their boots on the ground. The Nature paper “The Velocity of Climate Change,” published in December 2009, stated that plants and animals that require a narrow temperature range to live will be forced to migrate in order to remain in the same climate in which they evolved. Those that can keep pace with climate change will adapt. Those that cannot will likely perish (Read More). 

http://southwestclimatechange.org/impacts/water/groundwater

More than 35 percent of Arizona’s land and almost 60 percent of New Mexico’s land is used for farming and ranching. Thus climate change-related impacts on the Southwest landscape will most likely have significant impacts on the Southwest’s agricultural sectors. Changes in water availability, vegetation cover, carbon dioxide levels, and frequency of extreme events like flood, drought, or frost will impact crop and forage production, increasing costs for both producers and consumers. (read more)

In the West, as much as 70 percent of the region’s precipitation falls during winter. Arizona and New Mexico are critically dependant on this winter precipitation. The region’s two main water lifelines, the Colorado River and the Rio Grande, tap the winter snows in the Rocky Mountains for approximately 70 percent of their annual water flow. (Read more)

Current observations suggest that climate change is altering streamflows in ways that negatively impact water supply for southwestern populations. Many climate models suggest that these changes will worsen as the climate warms, accentuating the natural variability inherent in river flows.

Since water is one of the most vital resources in the arid Southwest, the consequences of reduced streamflows and changes in the timing of peak river flows will impact water consumption, agriculture production, economic growth, recreation opportunities, and electricity generation, among other vital services. (Find out more)