Read the full story from the University of Nebraska.
Weather and climate can contribute to civil unrest, especially in countries with little to no social safety nets, where people depend on subsistence farming to feed themselves and their families. The question is, can civil unrest be predicted along with the weather?
Read the full story at Texas Public Radio.
The San Antonio Water System reports the drought is sparking interest among customers about how to install a water-saving landscape.
The city-owned water utility offers education, water-saver coupons, and other rebates to make it easier to replace thirsty lawns with native or drought tolerant vegetation and do away with automatic sprinkler systems.
by Imtiaz Rangwala, University of Colorado Boulder
Much of the western U.S. has been in the grip of an unrelenting drought since early 2020. The dryness has coincided with record-breaking wildfires, intense and long-lasting heat waves, low stream flows and dwindling water supplies in reservoirs that millions of people across the region rely on.
Heading into summer, the outlook is pretty grim.
One driver of the Western drought has been persistent La Niña conditions in the tropical Pacific since the summer of 2020. During La Niña, cooler tropical Pacific waters help nudge the jet stream northward. That tends to bring fewer storms to the southern tier of the U.S. and produce pronounced drought impacts in the Southwest.
The other and perhaps more important part of the story is the hotter and thirstier atmosphere, caused by a rapidly warming climate.
As a climate scientist, I’ve watched how climate change is making drought conditions increasingly worse – particularly in the western and central U.S. The last two years have been more than 2 degrees Fahrenheit (1.1 Celsius) warmer than normal in these regions. Large swaths of the Southwest have been even hotter, with temperatures more than 3 F (1.7 C) higher. Studies suggest the Southwest’s ongoing 20-year drought is the most severe in at least 1,200 years, based on how dry the soils are.
A thristier atmosphere tends to extract more water out of the land. It exacerbates evaporative stress on the land, particularly when a region is experiencing below-normal precipitation. High evaporative stress can rapidly deplete soil moisture and lead to hotter temperatures, as the evaporative cooling effect is diminished. All this creates hydroclimatic stress for plants, causing restricted growth, drying and even death.
As a consequence of a warming climate, the U.S. Southwest has seen an 8% increase in this evaporative demand since the 1980s. This trend is generally happening across other parts of the country.
The thistier atmosphere is turning what would otherwise be near-normal or moderately dry conditions into droughts that are more severe or extreme. As the climate heats up further, the increasing atmospheric thirst will continue to intensify drought stress, with consequences for water availability, long-lasting and intense heat stress, and large-scale ecosystem transformation.
Climate models project ominous prospects of a more arid climate and more severe droughts in the Southwest and southern Great Plains in the coming decades.
In addition to direct impacts of increasing temperatures on future droughts, these regions are also expected to see fewer storms and more days without precipitation. Climate models consistently project a poleward shift in the midlatitude storm tracks during this century as the planet heats up, which is expected to result in fewer storms in the southern tier of the country.
The changing nature of droughts is a concern even in parts of the U.S. that are expected to have a net increase in annual precipitation during the 21st century. In a hotter future, because of the high evaporative demand on the land, prolonged periods with weeks to months of below normal precipitation in these areas can lead to significant drought, even if the overall trend is for more precipitation.
Large parts of the northern Plains, for example, have seen precipitation increase by 10% or more in the last three decades. However, the region is not immune to severe drought conditions in a hotter climate.
At the tail end of what was the wettest decade on record in the region, the northern Plains experienced an intense flash drought in the summer of 2017 that resulted in agricultural losses in excess of $2.6 billion and wildfires across millions of acres. Record evaporative demand contributed to the severity of the flash drought, in addition to a severe short-term precipitation deficit. A flash drought is a drought that intensifies rapidly over a period of a few weeks and often catches forecasters by surprise. The likelihood of flash droughts that can cause severe impacts to agriculture and ecosystems and promote large wildfires is expected to increase with a warmer and thirstier atmosphere.
Flash droughts are also emerging as a growing concern in the Northeast. In 2020, much of New England experienced an extreme hydrologic drought, with low stream flows and groundwater levels and widespread crop losses between May and September. Aided by very warm and dry atmospheric conditions, the drought developed very rapidly over that period from what had been above-normal wet conditions.
As humanity enters a hotter future, prolonged periods of weeks to months of below-normal precipitation are going to be of a greater concern almost everywhere.
Other forms of droughts are also emerging.
Atmospheric heating is causing snow droughts as more precipitation falls as rain rather than snow and snow melts earlier. Shorter snow seasons and longer growing seasons because of warmer temperatures are changing the timing of ecological responses.
Land is greening up earlier and causing an earlier loss of water from the land surface through evapotranspiration – the loss of water from plants and soil. This could result in drier soils in the latter half of the growing season. As a result, parts of the central and western U.S. could see both increased greening and drying in the future that are seasonally separated across the growing season.
With a rapidly changing climate, we are entering unfamiliar territory. The world will need new ways to better anticipate future droughts that could transform natural and human systems.
Imtiaz Rangwala, Research Scientist in Climate, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Read the full story at Grist.
New research shows that dry weather is coming on more quickly than before, with little advance warning.
Read the full story at e360.
Facing a changing climate, some southwestern U.S. cities such as San Diego, Phoenix, and Las Vegas have embraced innovative strategies for conserving and sourcing water, providing these metropolitan areas with sufficient water supplies to support their growing populations.
Read the full story from Utah State University.
Trees have a complex relationship with snow and energy as the season warms up, but new research shows that big trees can protect melting snowpacks in water-stressed environments.
Read the full story at e360.
In the midst of an historic megadrought, states in the American West are embracing cloud seeding to increase snow and rainfall. Recent research suggests that the decades-old approach can be effective, though questions remain about how much water it can wring from the sky.
Read the full story at the University of California Santa Barbara.
Maps of the American West have featured ever darker shades of red over the past two decades. The colors illustrate the unprecedented drought blighting the region. In some areas, conditions have blown past severe and extreme drought into exceptional drought. But rather than add more superlatives to our descriptions, one group of scientists believes it’s time to reconsider the very definition of drought.
by William R. Cotton, Colorado State University
Forecasters at the National Oceanic and Atmospheric Administration issued their U.S. spring outlook on March 17, 2022, and their top concern was worsening drought in the West and southern Plains. Several western states have experimented with cloud seeding to try to increase precipitation, but how well does that actually work? Atmospheric scientist William Cotton explains.
On mountain peaks scattered across Colorado, machines are set up to fire chemicals into the clouds in attempts to generate snow. The process is called cloud seeding, and as global temperatures rise, more countries and drought-troubled states are using it in sometimes desperate efforts to modify the weather.
But cloud seeding isn’t as simple as it sounds, and it might not be as promising as people wish.
As an atmospheric scientist, I have studied and written about weather modification for 50 years. Cloud seeding experiments that produce snow or rain require the right kind of clouds with enough moisture, and the right temperature and wind conditions. The percentage increases in precipitation are small, and it’s difficult to tell when snow or rain fell naturally and when it was triggered by seeding.
The modern age of weather modification began in the 1940s in Schenectady, New York.
Vince Schaefer, a scientist working for General Electric, discovered that adding small pellets of dry ice to a freezer containing “supercooled” water droplets triggered a proliferation of ice crystals.
Other scientists had theorized that the right mix of supercooled water drops and ice crystals could cause precipitation. Snow forms when ice crystals in clouds stick together. If ice-forming particles could be added to clouds, the scientists reasoned, moisture that would otherwise evaporate might have a greater chance of falling. Schaefer proved it could work.
On Nov. 13, 1946, Schaefer dropped crushed dry ice from a plane into supercooled stratus clouds. “I looked toward the rear and was thrilled to see long streamers of snow falling from the base of the cloud through which we had just passed,” he wrote in his journal. A few days later, he wrote that trying the same technique appeared to have improved visibility in fog.
A colleague at GE, Bernie Vonnegut, searched through chemical tables for materials with a crystallographic structure similar to ice and discovered that a smoke of silver iodide particles could have the same effect at temperatures below -20 C (-4 F) as dry ice.
Their research led to Project Cirrus, a joint civilian-military program that explored seeding a variety of clouds, including supercooled stratus clouds, cumulus clouds and even hurricanes. Within a few years, communities and companies that rely on water were spending US$3 million to $5 million a year on cloud-seeding projects, particularly in the drought-troubled western U.S., according to congressional testimony in the early 1950s.
The results of about 70 years of research into the effectiveness of cloud seeding are mixed.
Most scientific studies aimed at evaluating the effects of seeding cumulus clouds have shown little to no effect. However, the results of seeding wintertime orographic clouds – clouds that form as air rises over a mountain – have shown increases in precipitation.
There are two basic approaches to cloud seeding. One is to seed supercooled clouds with silver iodide or dry ice, causing ice crystals to grow, consume moisture from the cloud and fall as snow or rain. It might be shot into the clouds in rockets or sprayed from an airplane or mountaintop. The second involves warm clouds and hygroscopic materials like salt particles. These particles take on water vapor, becoming larger to fall faster.
The amount of snow or rain tied to cloud seeding has varied, with up to 14% reported in experiments in Australia. In the U.S., studies have found a few percentage points of increase in precipitation. In a 2020 study, scientists used radar to watch as 20 minutes of cloud seeding caused moisture inside clouds to thicken and fall. In all, about one-tenth of a millimeter of snow accumulated on the ground below in a little over an hour.
Another study, in 2015, used climate data and a six-year cloud-seeding experiment in the mountains of Wyoming to estimate that conditions there were right for cloud seeding about a quarter of the time from November to April. But the results likely would increase the snowpack by no more than about 1.5% for the season.
While encouraging, these experiments have by no means reached the level of significance that Schaefer and his colleagues had anticipated.
Scientists today are continuing to carry out randomized seeding experiments to determine when cloud seeding enhances precipitation and by how much.
People have raised a few concerns about negative effects from cloud seeding, but those effects appear to be minor. Silver ion is a toxic heavy metal, but the amount of silver iodide in seeded snowpack is so small that extremely sensitive instrumentation must be used to detect its presence.
Meanwhile, extreme weather and droughts are increasing interest in weather modification.
The World Meteorological Organization reported in 2017 that weather modification programs, including suppressing crop-damaging hail and increasing rain and snowfall, were underway in more than 50 countries. My home state of Colorado has supported cloud-seeding operations for years. Regardless of the mixed evidence, many communities are counting on it to work.
This article was updated March 17, 2022, with NOAA’s U.S. spring climate and weather outlook.
William R. Cotton, Professor Emeritus of Meteorology, Colorado State University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Source: California Department of Water Resources
The Department of Water Resources (DWR) has launched a new website, California Water Watch, that helps Californians easily access information on current local and statewide water conditions – down to their own region and even neighborhood.
“The variability of California’s climate and current water conditions we are experiencing now make this data more important than ever. Climate whiplash is our new reality living in this State, and we are innovating and developing new tools like California Water Watch to provide water managers, researchers, and policymakers with the data necessary to make better informed decisions about our limited water supply,” said DWR Director Karla Nemeth.
The website brings together data from DWR and other sources to provide dynamic real-time information on precipitation, temperature, reservoirs, snowpack, groundwater, streamflow, soil moisture, and vegetation conditions. Users can enter an address to see local conditions, including daily precipitation and temperature statistics, for their area and links to water supplier information. The website also allows users to compare data on local conditions by year and by region.
The website was developed in response to Governor Newsom’s call for a California-centric version of the U.S. Drought Monitor website in his drought state of emergency proclamation. The website was also recommended in the California Natural Resources Agency’s report to the Legislature on lessons learned from the 2012-2016 drought.
California Water Watch also includes precipitation forecast maps and links to other forecasting products, all from one easy-to-use web page. Regular hydroclimate summaries developed by California State Climatologist Mike Anderson will also be posted to the California Water Watch website. These summaries will succinctly describe what current water conditions look like in California and their impacts on the current drought.
California Water Watch is just one of many tools being leveraged and developed by DWR to keep Californians informed about current conditions and to improve water supply forecasting. For more information or to access the California Water Watch website today, visit https://cww.water.ca.gov. For information about other DWR and State drought response efforts and funding programs, visit drought.ca.gov/.
For more information: Akiela Moses, Information Officer, Public Affairs, Department of Water Resources, 916-820-7669 | Akiela.Moses@water.ca.gov
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