The University of Arizona



Communicating CPC’s Seasonal Forecasts: It’s Complicated

Saturday, September 3, 2011

Many of us have seen the seasonal outlooks issued by the Climate Prediction Center (CPC) forecasters. These predictions are extremely important to those who have to make choices based on temperature and precipitation, such as natural resource managers, farmers, and ranchers. But there is a lot of information in the shading and numbers on these maps, and it’s not always clear what it all means. (Read More)


Monsoon Extremes, Past and Future

Monday, June 13, 2011

We’re all itching to know if the monsoon will deliver this year, especially with the record wildfires, the widespread drought, and the closure of national forests across Arizona and New Mexico. Since our records of rainfall only go back to 1900, it’s hard to tell if the monsoon could get even stronger, or weaker, or if there could be periods of persistently strong or weak monsoons (e.g., ten years in a row of weak monsoons). To get at this information requires longer records of monsoon variability. Luckily, there are many archives of climate in the natural world. (Read More)

Southwestern Trees Hold the History—and Future?—of El Niño

Tuesday, May 10, 2011

The impact of tropical Pacific ocean temperatures on the hydroclimate of the Southwest is profound: on timescales of 2-8 years, El Niño and La Niña events influence the amount of winter precipitation we receive. Trees living across the Southwest region record these changes in moisture in the width of their rings, providing us with a history of precipitation going back thousands of years or longer in some places. (Read More)

Will Climate Change Impact Nuclear Energy in the Southwest?

Friday, April 8, 2011

Author: Britain Eakin

In the process of generating nuclear-based electricity, large amounts of cool water are needed to  maintain safe temperatures in the reactors. This is why the overwhelming majority of nuclear power plants are located adjacent to bodies of water; they divert water from these sources for cooling, and then release it back into the same sources. Climate change has the potential to significantly impact water availability and water temperatures, especially here in the Southwest; this raises the question of whether nuclear energy production could be affected by climate change as well. (Read More)

Managing Changing Landscapes – We Have the Tools to Respond!

Monday, February 14, 2011

Author: Marcos Robles

A slew of articles in the scientific literature and popular media report how the Southwest is one of the epicenters for climate change impacts in North America. Over the last half century, warming across the region has contributed to larger wildfires, widespread piñon tree mortality, declining snow packs and earlier stream flows. While these reports express the urgency of responding to climate change, they also raise many questions. (Read More)

Megadrought: Is the Past a Key to Our Future?

Saturday, December 4, 2010

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)

Western Fire on the Rise

Friday, October 29, 2010

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)

The Southwest Monsoon Under Climate Change: What the Models Tell (and Don’t Tell) Us

Friday, October 15, 2010

 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. 


Climate Models Versus Weather Models: Different Approaches for Different Needs

Thursday, October 7, 2010

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)

What’s Ahead for the Climate of the Southwest?

Friday, September 10, 2010

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)


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