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Mississippi River Running Dry | Earth Wise

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Water levels in the lower Mississippi River are running very low.  During September, the readings in Memphis, Tennessee were within inches of the all-time low.  The situation is causing real problems for the grain export industry.

The water levels of the lower Mississippi are determined by the amount of rainfall in the upper Midwest.  At the point where the Ohio and Mississippi Rivers come together, about 90% of the water headed for the lower Mississippi has been accumulated.

Almost 400 miles of the Mississippi have experienced water levels at or below critical levels for shipping.  During September, parts of the Mississippi have been closed to ship traffic more than 20 times.  At least 36 vessels were reported to have run aground.

The low water levels on the river have caused shippers of soybean and corn exports to lighten their loads to keep the vessels from running aground.  They have also reduced how many barges they pull at once in order to be able to navigate shipping channels that have narrowed because of the reduced water levels.

Fall is the busiest grain export season for the region.  About 60% of grain exports from the Midwest leave the U.S. through terminals on the Gulf Coast.  The low levels of the Mississippi River threaten gridlock for this vital industry.  It has caused freight costs to be the highest since historic river lows last year caused U.S. grain to be less competitive globally.

Unfortunately, October is not normally a strong precipitation month, but the hope is that the El Niño now underway may lead to increased precipitation in the Southern U.S.

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Mississippi River Nears Historic Lows, Putting Grain Exports at Risk

Photo, posted March 8, 2023, courtesy of Errol Sandler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Great Salt Lake In Danger | Earth Wise

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Utah’s Great Salt Lake has been plagued by excessive water use and extensive drought conditions.  As of January, the lake dropped to record-low water levels, losing 73% of its water and exposing 60% of its lakebed. According to scientists, the lake could disappear entirely within five years.

Great Salt Lake is what is known as a “terminal lake,” which means that it is fed only by rain, snow, and runoff and has no rivers that take water to the ocean.  As a result, salt and minerals build up over time.  With so much salt in the water, only brine flies and shrimp can survive in it.  The unique ecosystem supports 10 million migratory birds.  As the lake continues to dry up, the water is becoming too salty for even algae and microbes to survive.  With shallow mud replacing previous shallow water, the nests of the 80,000 white pelicans that annually come to the lake are endangered by predators that can simply walk over to the eggs.

The historic low water levels have exposed 800 square miles of lakebed.  This lakebed holds centuries of natural and manmade toxins like mercury, arsenic, and selenium.  The exposed mud ultimately turns to dust that is carried off into the air.  This is contributing to what is already some of the worst winter air pollution in the nation.  Scientists warn that the unfolding ecological disaster may become a human health disaster.

State officials and university researchers have formed a “Great Salt Lake Strike Team” looking for ways to get more water to the lake.  There are a number of so-called moonshot proposals to save the lake.  It remains to be seen what will be done, but the clock is ticking.

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Great Salt Lake will disappear in 5 years without massive ‘emergency rescue,’ scientists say

Scientists fear a Great Toxic Dustbowl could soon emerge from the Great Salt Lake

Photo, posted September 19, 2009, courtesy of John Morgan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon In The Congo Peatlands | Earth Wise

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The Congo peatlands in central Africa are the world’s largest tropical peatlands complex, occupying an area of 65,000 square miles, about the size of the entire state of Florida. Peatlands represent a huge store of carbon and therefore are important to the stability of the climate.

A study by scientists at the University of Leeds and University College London found that around the time that Stonehenge was built – about 5,000 years ago – there was an extended drying period in central Congo and the peatlands started emitting carbon dioxide rather than storing it.  Over the course of time, the climate in the area got wetter again and over the past 2,000 years, the Congo peatlands have been a place that takes large amounts of carbon out of the atmosphere.

The study utilized peat samples taken from beneath remote swamp forests to build a record of the vegetation and rainfall in the central Congo Basin over the past 17,500 years.

In a paper published in Nature, the researchers warn that if modern-day global warming produces extended droughts in the Congo region, history could repeat itself and the peatlands could once again become carbon emitters.  If that were to happen, over 30 billion tons of carbon could be released into the atmosphere.  That is the equivalent to the total global emissions from fossil fuel burning over a three-year period.

There is some evidence that dry seasons are lengthening in the Congo Basin, but it is unknown if these will continue.  In any case, the study reveals that peatlands are more vulnerable than previously thought and need to be protected.  They are some of the most wildlife and carbon-rich ecosystems on Earth.

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Congo peatlands could release billions of tonnes of carbon

Photo, posted November 5, 2016, courtesy of Roni Ziade / Forest Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Windows To Cool Buildings | Earth Wise

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About 15% of global energy consumption is for cooling buildings.  Because of this, there is an ever- growing need for technologies that can more efficiently cool buildings.   Researchers at Notre Dame University have used advanced computing technology and artificial intelligence to design a transparent window coating that is able to lower the temperature inside buildings without using any energy.

The idea is to create a coating that blocks the sun’s ultraviolet and near-infrared light, which are parts of the solar spectrum that otherwise pass through glass and help to heat an enclosed room.  Cooling needs can be reduced further if the coating can radiate heat from the surface of the window so it can pass through the atmosphere into space.  Designing a coating that does both of those things simultaneously while transmitting visible light is difficult.  Coatings should not interfere with the view out the window.

The Notre Dame researchers used advanced computer modeling to create a so-called transparent radiative cooler that meets these goals.  The coating consists of alternating layers of common materials like silicon dioxide, silicon nitride, and aluminum oxide or titanium dioxide on top of a glass base and topped with a film of polydimethylsiloxane.  The computing method was able to optimize this structure far faster and better than conventional design techniques.

The researchers say that in hot, dry cities, the coating could potentially reduce cooling energy consumption by 31% compared with conventional windows.  The same materials could be used in other applications, such as car and truck windows.  In addition, the quantum computing-enabled optimization method used for this work could be used to design other composite materials.

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Clear window coating could cool buildings without using energy

Photo, posted September 6, 2015, courtesy of Robert Otmn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And The Color Of Lakes | Earth Wise

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According to a new study recently published in the journal Geophysical Research Letters, blue lakes around the world are at risk of turning green-brown if climate change continues unabated. 

For the study, the research team used over five million satellite images of more than 85,000 lakes and reservoirs around the globe between 2013 and 2020 in order to determine each lake’s most common water color.  Since lake color can change seasonally, the researchers assessed the most frequent lake color during those seven years. 

Algae and sediments affect the color of lakes.  But the study found that precipitation, air temperature, lake depth, and elevation also play major roles in determining a lake’s most common water color. 

The research team found that blue lakes account for less than one-third of lakes worldwide.  Blue lakes tend to be deeper and are often found in cool, high latitude regions with high precipitation and winter ice cover.  Meanwhile, green-brown lakes, which account for 69% of all lakes, are found in drier regions, continental interiors, and along coastlines. 

As global temperatures rise, lakes will warm, and warmer water produces more algal blooms.  As a result, the researchers expect the changing climate to decrease the percentage of blue lakes, many of which are found in the Rocky Mountains, northeastern Canada, northern Europe and New Zealand. 

Water color is a simple but viable way to measure water quality that can be done on a global scale using satellites.  This approach provides researchers with a way to study how lakes – even the remote ones – are changing.  

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Climate change is making lakes turn green-brown

Photo, posted August 27, 2011, courtesy of Paul Schultz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Vanishing Arctic Lakes | Earth Wise

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In recent decades, the warming in the Arctic has been much faster than in the rest of the world.  The phenomenon is known as Arctic amplification.  A study by the Finnish Meteorological Institute published in August in Communications Earth & Environment determined that during the past 43 years, the Arctic has been warming nearly four times faster than the rest of the globe.  The result of this amplified warming has been that glaciers are collapsing, wildlife is struggling, and habitats continue to disappear at a record pace.

Research published by the University of Florida has identified a new threat associated with Arctic amplification: lakes in the Arctic are drying up.

Over the past 20 years, many Arctic lakes have shrunk or dried up completely across the entire pan-Arctic region, which spans the northern parts of Canada, Russia, Greenland, Scandinavia, and Alaska.

Arctic lakes are essential elements of the Arctic ecosystem and for the indigenous communities that live in the region.  They provide a critical source of fresh water for those communities and local industries. 

The rapid decline of Arctic lakes is unexpected.  Earlier predictions were that climate change would first actually expand lakes in the region as ground ice melted.  Lakes drying out was not expected until much later in this century or even in the 22nd century.  Instead, it appears that thawing permafrost may drain lakes and overwhelm the expansion effect caused by melting ice.  The theory is that thawing permafrost decreases lake area by creating drainage channels and increasing soil erosion.

The finding suggest that permafrost thawing is occurring faster than anticipated, which presents many additional problems.

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As the climate crisis intensifies, lakes across the Arctic are vanishing

Photo, posted June 20, 2014, courtesy of Bob Wick / Bureau of Land Management via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Death Valley Flooding | Earth Wise

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Furnace Creek in Death Valley is the driest place in North America.  Its average annual rainfall is under two inches.  On August 5th, a thousand-year rainfall event dropped 1.46 inches of rain – about three-quarters of a year’s precipitation.  The all-time record for a single day is 1.47 inches, set in April 1988.  The storm did break the record for the most rain ever recorded in August, which averages just over a tenth of an inch of rain for the entire month.

The flash flood washed debris over roads, swept away and buried cars, knocked a water facility offline, damaged buildings, and stranded about a thousand visitors and staff in Death Valley National Park. By the next day, the flood water had mostly receded, and stranded visitors could be escorted out of the park by National Park personnel.

Death Valley sits at 282 feet below sea level.  If it were not for the extremely arid climate there, Death Valley would likely be filled with water.  However, humid air masses traveling east from the Pacific Ocean have to cross four mountain ranges before they reach the desert valley.  Those air masses lose their moisture in the form of rain on the western slopes of the mountain, leaving a dry area, or rain shadow, on the eastern sides.  By the time the air masses reach Death Valley, they are bone dry.  On rare occasions, the lowest spot in the valley fills with water forming a wide, shallow lake, known as Lake Badwater. 

The extreme heat and aridity of Death Valley evaporates the temporary lake quickly, returning the valley to its usual state.  Furnace Creek still holds the record for the highest air temperature ever recorded:  134 degrees Fahrenheit.

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Death Valley Flash Flooding

Photo, posted April 7, 2021, courtesy of Matthew Dillon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Alaskan Wildfires | Earth Wise

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Alaska is on a pace for a record fire season this year.  As of mid-July, more than 2.7 million acres had burned, which is more than 10 times the total area burned in all of 2021.

Alaskan fires have been spurred on by warm temperatures, a diminished snowpack, and an unusually large number of lightning strikes.  May was one of the warmest and driest on record leading to lots of fires in June.  More than 300 wildfires ignited during June.  Many were sparked by nearly 5,000 lightning strikes early in the month.

There have already been some very large fires, including the East Fork Fire, near the Yukon Delta which had burned more than 250,000 acres by the beginning of July, and the Lime Complex Fire, in the southwest part of the state, which had burned more than 865,000 acres by mid-July.

The all-time record fire season in Alaska was 2004, when more than 6 million acres went up in flames.   Wildfires are a natural part of the Boreal North ecosystem: the great northern forest region.  But the fires occurring now are very different from those of a century ago and more.   The combination of more fuel in the form of dry vegetation, more lightning strikes, higher temperatures, and lower humidity leads to fires that burn hotter and burn deeper into the ground.  Such fires don’t just scorch trees and burn the undergrowth.  They consume everything leaving a barren landscape of ash.  Million-acre fires occur more than twice as often as they did before 1990.

The state may set a new record for wildfire acreage before the season is over.  Nearly 6,000 firefighters and support personnel continue to battle blazes across the state.

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Alaska Is on Track for a Record Fire Season

Photo, posted June 18, 2022, courtesy of Ryan McPherson/BLM Alaska Fire Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Historic Western Drought | Earth Wise

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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.

January Climate Report Card | Earth Wise

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January was the sixth-warmest January in the 143 years of global climate record keeping.  The global land and ocean surface temperature was 1.6 degrees Fahrenheit above the 20th century average.

Meanwhile, the United States had its coolest January since 2014, although the month still ranked nearly a degree above the long-term average across the nation.  This January was also the driest January in eight years and was one of the top- 15 driest Januarys on record.  That being said, there was the so-called Bomb Cyclone late in the month that dumped 1-2 feet of snow and brought blizzard conditions along the eastern seaboard and set a one-day snowfall record in Boston.

Global conditions and regional and local conditions can be very different.  In the big picture, January was the 46th consecutive January and the 445th consecutive month with temperatures above the 20th century average.

And while the US had a fairly cool January, South America saw its second-warmest January on record, Asia had its fourth warmest, and Oceania had its seventh warmest.

Apart from temperatures, Antarctic sea ice coverage was the second smallest January extent in 44 years.  Arctic ice was 208,000 square miles below the 1981-2010 average, although it was the largest since 2009.

Even as the global climate warms, local and regional climate conditions will continue to have unique and variable characteristics over the course of time.  Every time there’s a bout of cold weather, it isn’t time to stop being concerned about climate change.

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January 2022 was Earth’s 6th warmest on record

Photo, posted January 6, 2013, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lake Tuz Is Disappearing | Earth Wise

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Lake Tuz is Turkey’s second-largest lake and one of the world’s largest hypersaline lakes.  Its high salt content makes it an ideal breeding ground for some migratory bird species, including flamingos, which are often present there in huge numbers in the spring and summer.

Now, Lake Tuz rarely spans an area much larger than a puddle. In some summers, it completely dries up.  It did so this past summer, which resulted in the deaths of thousands of flamingos.

According to experts, Lake Tuz is a victim of climate change-induced drought, which has hit the region hard, and decades of harmful agricultural policies that exhausted the underground water supply.

Water in this region has become increasingly scarce.  The Mediterranean Basin has already seen more frequent and intense droughts, and is considered a climate change hotspot. 

According to new research, which was recently published in the journal Regional Environmental Change, Lake Tuz generally contained enough water in August for the lake to be considered permanent up until 2000.  But between 2001 and 2016, something shifted.  Water spanned less than 20% of the lake in every August except for one, and droughts became more frequent and intense. And in some years, the lake completely dried up.   

What caused this change?  According to the research team, Lake Tuz’s decline coincided with the excessive use of groundwater and surface water resources responsible for feeding the lake.  Some streams were rerouted for agricultural purposes, while others were dammed.  And when surface water sources dwindled, people turned to groundwater that historically fed the springs in Lake Tuz. 

Lake Tuz may be on the brink of extinction. 

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Impact of climate variability on the surface of Lake Tuz (Turkey), 1985–2016

Disappearing Lake Tuz

Photo, posted August 16, 2021, courtesy of Godot via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Drought And Desalination | Earth Wise

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The Western US is currently experiencing what might be the worst drought in over 1,000 years.   The region has seen many droughts in the past, but the changing climate is making dry years drier and wet years wetter.   Diminishing snow-packs mean that rivers, streams, reservoirs, and soil are not replenished enough in the spring and summer.

Meanwhile, the Southwest has seen a growth rate over the past 60 years that is twice that of the rest of the country.  More and more people are moving to areas expected to get even drier in the years to come.  There have been unprecedented water allocation cuts from the Colorado River – which provides water to seven states – and there have been shutdowns of hydroelectric power plants.

Only three percent of the planet’s water is fresh water and much of that is not available for our use.  Over 120 countries have turned to desalination for at least some of their drinking water.  In the US, the largest plant is in Carlsbad, California and a huge new plant is likely to be built in Huntington Beach, California.

Desalination has its drawbacks.  It is expensive, consumes large amounts of energy, and has detrimental environmental impacts.  Most of the world’s desal plants now use membrane filtration technology but there are still many that use the thermal distillation method.

There are efforts around the world aimed at improving desalination.  A giant project in Saudi Arabia is based on solar heating of sea water.  The U.S. Army and the University of Rochester are working on a different solar-based system.  European companies are developing a floating seawater desalination plant powered by wind energy. 

Droughts seem to be here to stay.  Finding better ways to get fresh water is essential.

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A 1,000 Year Drought is Hitting the West. Could Desalination Be a Solution?

Photo, posted May 31, 2021, courtesy of Frank Schulenburg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Dangerous Fire Season | Earth Wise

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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.

A Global Assessment Of Groundwater Wells | Earth Wise

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Water is a fundamental need for every human being on the planet.  Each person requires more than five gallons of clean and safe water a day for drinking, cooking, and keeping clean.

Groundwater wells remain one of the primary sources of drinking water.  In fact, more than half of the world’s population gets its drinking water from groundwater wells.  Groundwater wells also sustain more than 40% of irrigated agriculture.

Researchers from UC Santa Barbara have recently compiled the most comprehensive assessment of groundwater wells to date.  Their research, which was recently published in the journal Science, spanned 40 countries, which collectively account for more than 50% of all groundwater pumping. 

According to the survey’s findings, many wells are at risk of running dry – up to one in five wells, to be exact.  The researchers compared the depths of water tables against well depths. They found that 6% to 20% of the wells in the study were at risk of running dry if water levels continue to decline by just a few meters.

In many areas where groundwater levels are declining, the research team found that new wells are not being drilled deeper to keep pace with the falling water table. As a result, newer wells are just as vulnerable as older wells should groundwater levels continue to decline.  

The researchers hope to expand on this study to include data from China, Iran, and Pakistan, three major users of groundwater from which the researchers could not obtain records.  The researchers also plan to investigate how quickly water tables are dropping and where the trend is accelerating.   

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The largest assessment of global groundwater wells finds many are at risk of drying up

Photo, posted January 20, 2018, courtesy of François Molle via Water Alternatives Photos on Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Self-Watering Soil | Earth Wise

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Researchers at the University of Texas at Austin have created a new type of soil that can pull water from the air and distribute it to plants.  Such soil has the potential to expand the map of farmable land to previously inhospitable places as well as to reduce water use in agriculture in an era of growing droughts.

The team’s atmospheric water irrigation system makes use of super-moisture-absorbent gels to capture water from the air.  When they are heated to a high enough temperature, the gels release the water, making it available to plants.

The gels in the soil pull water out of the air during cooler, more humid periods at night and when the sun heats the soil during the day, the water-containing gels release their contents into the soil.

Each gram of soil can extract about 3-4 grams of water.  Depending on the specific crop, somewhere between a couple of ounces and 2 pounds of the soil can provide enough water to irrigate a square yard of farmland.

Experiments on the soil found that it retains water better than the sandy soils found in dry areas and needs much less water to grow plants.

In one experiment, radish plants germinated in the soil all survived a 14-day period without any irrigation beyond the initial watering when they were planted.  Radish plants in ordinary sandy soil irrigated for the first four days of the experiments lasted no more than two days further without watering.

The Austin group has been developing gel-polymer materials that work like super-sponges for two years.  These materials extract large amounts of water from the ambient air, clean it, and release it when heated with solar energy.

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Self-Watering Soil Could Transform Farming

Photo, posted October 21, 2020, courtesy of the U.S. Department of Agriculture via Flickr. USDA Media by Lance Cheung.

Earth Wise is a production of WAMC Northeast Public Radio.

Crops May Need To Move | Earth Wise

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California has unique micro-climate diversity that creates ideal growing conditions for a wide range of crops.  One third of the vegetables and two-thirds of the fruits and nuts we eat in this country are grown on the more than 76,000 farms in California.  But as the climate continues to change, many farmers have started to worry about where and when crops can be grown in the future.   Within the next 20 years or so, some parts of California may become too hot and dry to sustain agricultural production.

According to new research from the Lawrence Berkeley National Laboratory, by the years 2045-2049, warmer temperatures will have a significant effect on cool-season crops such as broccoli and lettuce such that their growing season will need to shift.  On the other hand, warm-season crops like cantaloupe, tomatoes, and carrots will need to move to entirely new growing locations.

The study looked at five key crops that are produced more in California than elsewhere and studied the climate conditions under which they prosper and those under which they fail.  They established the range of conditions for which the crops can remain successful.  Finally they looked at climate projections for various parts of the state.

California’s agriculture is an essential part of our food security, so it is important to predict how future warming will affect when and where crops can be grown.  Changing these things presents challenges.  For example, when considering relocating crops, growers have specialized knowledge of their land and their crops.  If crops need to move to a new area, either the farmers have to move to that area, or they have to grow a different crop.  Either way, it presents a practical and economic burden on the farmer.

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Some of America’s Favorite Produce Crops May Need to Get a Move On by 2045

Photo, posted June 16, 2011, courtesy of the U.S. Department of Agriculture via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dust From The Sahara | Earth Wise

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A vast cloud of dust from the Sahara Desert blanketed the Caribbean in late June before drifting across the southeastern U.S.  The phenomenon is nothing new; only the magnitude of the occurrence this time around was unusual.  According to experts, this is the most significant Sahara dust event in 50 years.

The Sahara Desert is the major source on Earth of mineral dust, with some 60-200 million tons of it per year being lifted into the atmosphere.  Convection currents over hot desert areas lift the dust to very high altitudes.  From there, it can be transported worldwide by winds.   The dust, combined with the extremely hot, dry air of the Sahara Desert often forms an atmospheric layer called the Saharan Air Layer, which can have significant effects on tropical weather by interfering with the development of hurricanes.  The Saharan Air Layer typically moves across the North Atlantic every three to five days from late spring to early fall, peaking in the middle of the summer.  It can occupy a layer as much as two miles thick in the atmosphere.

The dust plume this summer was highly visible from space, covering thousands of miles of the Atlantic Ocean and the Caribbean Sea.

A common effect of Sahara dust is that normally blue skies can acquire a milky haze, but beyond that can lead to spectacular sunsets.  But apart from the visual spectacle, the dust can aggravate the conditions of people with asthma, respiratory illnesses, and allergies. On the positive side, as long as the dust is around, it is much less likely that tropical storms and hurricanes will form.

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Sahara dust blankets Caribbean, air quality hazardous

Photo, posted June 22, 2020, courtesy of Sagar Rana via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Keeping Charleston Dry | Earth Wise

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Charleston, South Carolina is visited by millions of tourists each year.  The town is a glimpse into the past, showcasing antebellum mansions, row houses, historic African American churches and scenic harbor views from a Civil War-era promenade.

Charleston is also visited more and more by water from rising seas and increasingly powerful storms.  The city is essentially drowning in slow motion and may soon face an existential threat to its survival.

Charleston has a harbor and three rivers and water from all these sources leaks in at every bend and curve, fills streets, disrupts businesses, and rushes into homes during storms.  Million-dollar antebellum mansions, built on spongy marsh and old tidal creeks, flood repeatedly.

City officials have endorsed a plan by the U.S. Army Corps of Engineers to wall off the historic downtown with an 8-mile-long seawall that would cost nearly $2 billion.  The proposed barricade is just one of many proposed projects to build seawalls, surge gates, levees, and other barriers to defend U.S. coastal cities in an era of rising seas and climate-fueled floods and storms.  A proposed flood wall in Miami would cost federal taxpayers $8 billion.

Researchers generally agree that sea levels are likely to rise by at least 3 feet by the end of the century.  Some experts believe the rise will be much greater.  So, a key question is whether these barriers will actually keep out the water.  Critics of many of the proposed solutions contend that they are doomed to fail.

Flooding has caused nearly $1 trillion worth of damage along the East and Gulf coasts over the past 40 years.  And things are almost certain to get worse in Charleston and other coastal cities.

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Fortress Charleston: Will Walling Off the City Hold Back the Waters?

Photo, posted October 7, 2015, courtesy of Jeff Turner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

American Robins And Climate Change | Earth Wise

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American robins are migratory songbirds that can be found throughout much of North America.  Named after European robins because of their reddish-orange breast, American robins are often found hopping across lawns and nesting on porches.  Their rich caroling is among the first pre-dawn bird songs heard in spring and summer.  

While some overwinter in northern parts of the United States and southern Canada, most American robins migrate south to overwinter in places like Florida and the Gulf Coast, as well as central Mexico and the Pacific Coast.  They typically head south by the end of August and return north sometime between February and March to their breeding grounds in Canada and Alaska.  They spend their short time there trying to find a mate, build a nest, raise a family, and consume enough food to sustain themselves on their long return journey south.

But climate change is making these seasonal rhythms less predictable.  According to a new study recently published in the journal Environmental Research Letters, American robin migration is kicking off earlier by about five days each decade.  The birds now migrate 12 days earlier than they did in 1994.  

For 25 years, researchers at Canada’s Slave Lake have been recording the timing of American robin spring migration.  They attached GPS devices to 55 robins, tracking their movements from April through June. The researchers linked the birds’ movement with weather data, including air temperature, snow depth, wind speed, and precipitation.  The results showed that robins start migrating north earlier when winters are warm and dry. 

Understanding the influence over the timing of migratory events is important because the timing of migration can influence reproductive success.

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A Migration Mystery

American robins now migrate 12 days earlier than in 1994

Photo, posted January 1, 2020, courtesy of Becky Matsubara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Monster Tumbleweeds

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Tumbleweeds have long been seen as symbols of America’s old west.  Tumbleweeds are a structural part of the above-ground anatomy of a number of species of plants known as diaspores.  Diaspores are essentially seed dispersal units.  In a few seed plants, they comprise most or all of the plant.  Once they are mature and dry, they detach from the roots and roll around due to the force of the wind.

There is a new species of gigantic tumbleweed – the Salsola ryanii – that is expanding its territory in the American west.  It is the result of a relatively unusual genetic process known as polyploidy, which produces offspring with multiple sets of chromosomes.  Researchers believe that that the new hybrid species of tumbleweed is healthier than earlier versions.  As a result, one geneticist described Salsola ryanii as a nasty species replacing other nasty species of tumbleweed in the US.

These tumbleweeds can grow up to 6 feet tall.  Tumbleweeds in general are invasive plants that cause traffic accidents, damage agricultural operations, and cause millions of dollars in property damage.  Last year, the town of Victorville in the California desert was buried in them, piling up to the second story of some houses.

Salsola ryanii has a relatively small range, but it is expanding rapidly.  The new study determined that it is more vigorous than its predecessors, which are invasive in 48 states.  The plant is an annual but tends to grow on the later side of winter.  It is one of the only things that is still green in late summer.  With summer rains increasing as the climate changes, these monster tumbleweeds are poised to wreak havoc.   The experts are warning that there should be efforts to suppress them before they take over.

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Monster tumbleweed: Invasive new species is here to stay

Photo, posted February 27, 2018, courtesy of Tracie Hall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)