The US Southwest May Already Be Drying Up
The weather patterns that normally bring rain to the Southwest have been disappearing and climate change could be the cause. Continue reading →
The Southwest is already the most arid part of the United States Now new research indicates it's becoming even more dry as wet weather patterns, quite literally, dry up.
The change could herald a pattern shift and raises the specter of megadrought in the region.
"We see a very intense trend in the Southwest," Andreas Prein, a postdoctoral researcher at the National Center for Atmospheric Research, said. "The Southwest might already have drifted into a drier climate state."
Prein, who led the research published on Thursday in Geophysical Research Letters, looked at weather patterns rather than average trends in precipitation. The team identified 12 major patterns, only three of which are favorable for rain in the Southwest.
In an ominous finding for the region, they found that over the past 30 years, those three rainy patterns are becoming less frequent and the rains and mountain snow that come with them are drying up.
Less rain and mountain snow in an already dry region is a recipe for severe drought. There's an 80 percent chance the region could face a megadrought lasting decades as the climate warms, according to research published last year. The new findings reinforce just how serious that threat is.
"Nowadays, the droughts are not the same as 30 years ago. They can be more intense and last longer than we would expect 30 years ago," Prein said.
While Prein did not look directly at whether the current drying was driven by climate change or natural forces, the main climatic driver is an increase in high pressure in the northeast Pacific Ocean that essentially steers stormy weather away from the region. (You might recall a feature called the ridiculously resilient ridge doing something similar and driving the California drought. That's kinda what's happening in the Southwest.)
"We would expect something like that from climate change," Prein said. "The only surprise was that this can be detected in observational datasets."
The findings have huge implications for a region that's home to some of the nation's fastest growing cities that are already battling over scarce water resources.
"If you look at average changes, you're missing most of what's actually going on," Daniel Swain, a PhD candidate at Stanford University, said. "Are wettest days becoming wetter, are the driest days becoming more common? It has a lot of practical implications for humans and ecosystems that are adapted to a certain degree."
Swain, who was not associated with the study, said that the approach of looking at pattern changes had the potential to be a more effective way to understand climate change and natural impacts that matter the most people.
"We feel changes in climate through weather. In some cases, it does help to think of climate change through the lens of changing weather patterns and this paper is one way of doing that," he said.
Adding to the woes is rising temperatures, which help bake in drought. While California has seen a big precipitation deficit, it's been record heat that's really helped turn the current drought into one of epic proportions. With heat projected to continue rising, it's clear the Southwest will have to adapt to more than just dry conditions.
More From Climate Central:
Southwest, Central Plains Face ‘Unprecedented' Drought El Niño Is Here, So Why Is California Still in Drought?
Climate Change Ups Odds of a Southwest Megadrought This article originally appeared on Climate Central, all rights reserved.
Precipitation across the United States that can be attributed to these changes in weather patterns. The gray dots show areas where the results are statistically significant. ANDREAS PREIN
The effects of global warming are frequently projected decades into the future, but two recent reports -- one from the
and the other
-- put into sharp focus visible consequences of our warming planet. An increase in temperature, extreme weather, loss of ice and rising sea level are just a few of changes we can measure right now. Let's take a look at some of the most concerning trends.
Glaciers are shrinking worldwide and permafrost is thawing in high-latitude and high-elevation areas, reports this year's Fifth Assessment Report from the Intergovernmental Panel on Climate Change.
Only a few extinctions are attributed to climate change, reports the IPCC, but climate change that occurred much more slowly, over millions of years, caused major ecosystem shifts and species extinctions. Land and sea animals are changing their geographic ranges and migratory patterns due to climate change.
Sea level around the world has increased by about 8 inches since 1880, reports the 2014 National Climate Assessment, which projects a 1 to 4 foot rise by the end of the century.
Excess CO2 is dissolving in the ocean and decreasing the pH of seawater. The ocean is about 30 percent more acidic than it was in pre-industrial times. More acidity in the oceans makes it harder for animals to form calcium carbonate shells and skeletons and erodes coral reefs.
The probability of a Sandy-like storm deluging New York, New Jersey and other parts of the East Coast has nearly doubled compared to 1950, according to the American Meteorological Society. Even weaker storms will be more damaging now than they were 10 years ago because of rising sea levels. Superstorm Sandy cost the nation $65 billion, according to the 2014 National Climate Assessment, and 2012's Hurricane Isaac cost $2.3 billion.
The global sea level rises along with the temperature for two major reasons. For one, heat causes water to expand, which causes the existing water to take up more space and encroach on the coast. At the same time, ice at the poles and in glaciers melts and increases the amount of water in the oceans.
Across the United States, heavy downpours are on the rise, especially in the Northeast and Midwest. Increases in extreme precipitation are expected for all U.S. regions, reports the 2014 National Climate Assessment.
The most recent IPCC report states with "very high confidence" that current climate-related extremes like heat waves, droughts, floods, cyclones and wildfires are showing that countries around the world, at all development levels, are significantly unprepared. The American Meteorological Society estimates that approximately 35 percent of the extreme heat in the eastern United States between March and May 2012 resulted from human activities' effects on climate. The AMS warned that deadly heat waves will become four times more likely in the north-central and northeastern United States as the planet continues to warm.