evacuations

California Flooding | Earth Wise

February 2, 2023 By EarthWise Leave a Comment

Starting in December, a series of “atmospheric rivers” brought record storms to California producing as much rain in three weeks in some areas as they normally have in an entire year. The historic levels of rain (and snow in the mountains) have swollen rivers, flooded roads and homes, forced evacuations, knocked out electric power for millions of people, and resulted in more than 20 deaths.

Atmospheric rivers are air currents that carry large amounts of water vapor through the sky. They are not unusual for California but recurrent waves of them like those that have happened recently are very infrequent. Studies by the U.S. Geological Survey have shown that such a phenomenon recurs in California every 250 years. There were a series of storms causing disastrous floods in California in 1861-62.

The atmospheric rivers are born in the warm waters of the tropical Pacific. During La Nina phases, the atmospheric rivers typically make landfall on the northern West Coast. During El Nino phases, atmospheric rivers are more likely to end up in Southern and Central California. During transitions between the phases, as is happening now, the storms can cover large parts of the state.

Modern forecasting is pretty good at predicting the forthcoming occurrence of these storms and has led to some helpful actions, such as reservoir operators preventing dams from overflowing or bursting. But there is a gap between science and decision-making. It is pretty clear what needs to be done when tornados or hurricanes are on the way. It is less clear what actions are appropriate when there are going to be repeated heavy rainstorms.

These storms will have an effect on California’s megadrought, but just how much of an effect remains to be seen.

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Web Links

Flooding in California: What Went Wrong, and What Comes Next

Photo, posted January 5, 2023, courtesy of Sarah Stierch via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Heatwaves And Alpine Mountain Climbing | Earth Wise

August 25, 2022 By EarthWise Leave a Comment

From June to August, there were persistent heat waves affecting parts of Europe that caused wildfires, evacuations, and heat-related deaths. Nearly 12,000 people died from heat stroke or other causes associated with the high temperatures. The highest temperature recorded during this period was 116.6 degrees F in Pinhao, Portugal on July 14th. The RAF base in Coningsby, Lincolnshire recorded a temperature over 104 degrees on July 19th, the highest ever recorded in the United Kingdom.

Among the effects of the multiple European heatwaves has been the cancellation of climbing tours up some of the most iconic peaks in the Alps, including Mont Blanc and the Matterhorn. The high temperatures and rapidly melting glaciers have made the climbing routes too dangerous. Overall, climbing cancellations occurred on about a dozen peaks, including the Jungfrau in Switzerland, which cancelled tours for the first time in a century.

In previous years, during warm summers, some of these climbing routes were closed in August, but the glaciers were already in a condition that usually only happens at the end of summer or even later.

The combination of heat and glacier melt can be treacherous. In July, 11 people were killed at Italy’s Marmolada glacier by falling ice and rock.

Glacial melt in the Alps is rapidly accelerating. The Forni Glacier, the largest valley glacier in Italy, has retreated two miles since 1860 and its area has shrunk by half. Forecasts are that it will retain only 20% of its current volume by 2050 and may disappear entirely by the end of the century. Half of the 4,000 glaciers in the Alps are expected to disappear by 2050.

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Web Links

European Heat Waves Force Closure of Classic Climbing Routes in Alps

Photo, posted September 4, 2020, courtesy of Dmitry Djouce via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dangerous Smoke From Australia’s Wildfires | Earth Wise

January 13, 2020 By EarthWise Leave a Comment

Wildfires raging across Australia have devastated large swathes of land and prompted one of the largest evacuations in the country’s history. The fires, which have scorched approximately 20 million acres, have also killed 27 people and affected an estimated one billion animals at the time of this recording. The fire season, though still young, already ranks as among the worst in Australia’s recorded history.

Away from the flames, millions more in Australia are breathing unhealthy air as a result of the smoke from these wildfires. Wildfires release all sorts of dangerous air pollutants, like carbon monoxide and nitrous oxide. But wildfires also release fine particulate matter (more commonly referred to as PM2.5), which can be transported long distances. Breathing in these microscopic particles can lead to respiratory and cardiovascular problems. High levels of PM2.5 are particularly harmful to older people, young children, and those with weakened immune systems.

The Australian capital city of Canberra has been covered in a thick haze of smoke from nearby wildfires. Canberra recorded its worst air quality day on January 2nd, when levels of PM2.5 spiked to more than 200 micrograms per cubic meter during the worst hour.

Smoke has also been fouling Sydney’s air off and on for months, with PM2.5 readings hitting nearly 400 micrograms per cubic meter last month during the highest hour of pollution.

The U.S. EPA has in place an annual PM2.5 standard of 12 micrograms per cubic meter and a daily (or 24 hour) standard of 35.

According to the IPCC, southern Australia is expected to see increased risk of fire as the planet continues to warm. Regrettably, this could be the new normal.

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Web Links

Millions of Australians Are Choking on Smoke From Wildfires

Photo, posted December 5, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.