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A Historic Western Drought | Earth Wise

April 1, 2022 By EarthWise Leave a Comment

The American Southwest has suffered from drought conditions since the year 2000. The drought has reduced water supplies, devastated farmers and ranchers, and it has helped to fuel numerous wildfires across the region. It has generally been considered to be worst in 500 years.

According to a recent analysis, the drought has become so severe that it has actually led to the driest two decades in at least 1,200 years and the changing climate is largely responsible. The summer of 2021 was especially dry; about 2/3 of the West was in severe drought conditions.

Scientists at UCLA used tree ring data to gauge drought. Based on that analysis, 2000-2021 is the driest 22-year period since 800 A.D. which is as far back as the data goes.

The study confirmed the role of temperature, more than precipitation, in driving exceptional droughts. Precipitation levels can go up and down over time and can vary in different regions. But the ongoing emissions of greenhouse gases into the atmosphere are causing temperatures to generally rise over time. Warmer temperatures make the air more capable of pulling water out of the soil, out of vegetation, out of crops, and out of forests. All of that makes drought conditions more severe.

A megadrought is generally considered to be one that is both severe and long. But even during one, there can be wet years. 2005 was a notable one. But there must be enough consecutive wet years to actually end a drought.

Several previous megadroughts over the past 1,200 years lasted as long as 30 years. So, the current drought is in full swing and may go on for a long time to come.

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How Bad Is the Western Drought? Worst in 12 Centuries, Study Finds.

Photo, posted September 25, 2021, courtesy of David Sierralupe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Dangerous Fire Season | Earth Wise

June 9, 2021 By EarthWise Leave a Comment

The western United States is entering the fire season under much worse drought conditions than last year. Last year, 15,800 square miles burned in the U.S., mostly in the West.

The western U.S. is in the midst of a 20-year mega-drought. Rainfall in the Rocky Mountains and farther west was the second lowest on record this April. The soil in the western half of the country is the driest it has been since 1895.

The situation is particularly bad in California and the Southwest. In March, less than a third of California was experiencing extreme or exceptional drought. Now, 73% of the state is. A year ago, a record-breaking fire season burned 4% of the state and, at that time, only 3% of California was in a state of extreme drought.

A year ago, no parts of Arizona, Nevada, or Utah were in extreme or exceptional drought. Now, more than 90% of Utah, 86% of Arizona, and 75% of Nevada face severe drought conditions. At this time last year, only 4% of New Mexico faced extreme drought but 77% does now.

These extreme drought conditions, which are believed to be linked to climate change, are causing increased tree mortality among many species, ranging from junipers in the Southwest even to drought-tolerant blue oaks in the San Francisco Bay Area.

Conditions are extremely ripe for a lot of forest fire this year. Last year was a terrible year for wildfires in the West and we are heading into a fire season with much drier fuels than there were last year. The risks of great damage from wildfires are higher than ever.

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US West Enters Fire Season Facing Extremely Dry Conditions

Photo, posted September 18, 2020, courtesy of USFS/National Interagency Fire Center via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Trouble For Monarchs | Earth Wise

April 14, 2020 By EarthWise Leave a Comment

Monarch butterflies have been in trouble for quite a while and now it seems like their prospects are worse than ever. Multiple surveys of butterfly populations are reporting plummeting numbers.

Western monarch butterflies spend their winters on the central California coast. Months later, they breed in California’s Central Valley and as far north and east as Idaho. But in recent years, it has become harder and harder to find them in their breeding sites.

The Western monarch population was in the millions in the 1980s. In 2017, an annual survey found 200,000 butterflies. In 2018 and 2019, only about 30,000 butterflies were tallied. The loss of Western butterflies in general has come about from a variety of factors, including development, climate change, farming practices and the widespread use of pesticides by farmers and on home and business lawns.

Scientists use the area of land that migrating Monarchs occupy in Mexico to gauge populations. This year, they covered about 7 acres, down from 15 acres in 2019.

Meanwhile, there are also far fewer Eastern monarch butterflies on the opposite side of the country. According to a new population survey, the Eastern monarch has passed the extinction threshold. Its population in 2020 dropped 53% from its already low 2019 numbers. Scientists were expecting lower numbers this year, but they were staggered by their findings.

Butterfly populations are quite variable, so it is possible that the drastic declines this year are not necessarily irreversible, but the news is not good. Researchers and environmental advocates continue to point out that mitigating the climate crisis, reducing pesticide use and planting pollinator gardens could help the butterflies to recover.

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Monarch Butterfly Populations Are Plummeting

Photo, posted September 7, 2017, courtesy of C. Watts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Droughts And Hydropower

February 7, 2019 By EarthWise Leave a Comment

Recent droughts in several western states have led to well-publicized problems including wildfires, loss of trees, and damage to crops. A lesser-known impact of drought conditions has been increases in emissions of carbon dioxide and harmful air pollutants from power generation.

When hydropower runs low in a drought, western states tend to ramp up power generation – and therefore emissions – from fossil fuels. According to a new study from Stanford University, droughts caused about 10 percent of the average annual carbon dioxide emissions from power generation in California, Idaho, Oregon and Washington between 2001 and 2015.

Water is used in electricity generation both directly for hydroelectric power and indirectly for cooling in thermoelectric power plants. When water for hydropower comes up short because of drought conditions, natural gas or coal-fired power plants are brought online to pick up the slack.

These drought-induced shifts in energy sources led to an estimated 100 million tons of carbon dioxide across 11 western states between 2001 and 2015. That is the equivalent of adding 1.4 million vehicles to the region’s roadways. California, whose legislature has mandated that the state be carbon-free by 2045, contributed about half of this total. Washington, which is considering a similar mandate, contributed nearly a quarter of the total.

Western states in recent years have suffered intense droughts that scientists expect to become more common as global warming continues to intensify. The new study indicates that in regions where clean, reliable hydropower has been an important part of the energy mix, it will be increasingly necessary to provide clean backup energy sources in order to meet emission reduction targets.

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Droughts boost emissions as hydropower dries up

Photo, posted March 7, 2016, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.