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Wildfires and water quality

August 11, 2025 By EarthWise Leave a Comment

Hotter and drier conditions driven by climate change are leading to an increasing number of wildfires in North America and around the world. The damage wildfires cause – to forests, homes, and communities – is well-known. But long after the flames are gone, the effects can linger, especially in rivers and streams, where water quality may suffer for years.

A new study by scientists at the CIRES institute at the University of Colorado Boulder analyzed more than 100,000 water samples from more than 500 sites across the Western U.S. and found that wildfires can degrade water quality for up to eight years after a fire. The research, which was recently published in the journal Nature Communications Earth & Environment, found elevated levels of organic carbon, nitrogen, phosphorus, sediment, and turbidity – the cloudiness of water – in basins affected by fire.

This large-scale analysis reveals watersheds take longer to recover from wildfires than previously thought, with widespread, long-lasting impacts often going undetected for years.

Organic carbon, phosphorus, and turbidity remain elevated for one to five years after a fire. Nitrogen and sediment levels stay notably high for up to eight years. Fire-driven impacts are worse in more forested areas.

Each watershed in the study responded differently depending on local conditions. In some places, sediment levels surged to as much as 2,000 times normal levels, while others remained relatively unchanged.

The research team hopes its findings can help guide future planning efforts to improve wildfire resilience.

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Wildfires threaten water quality for years after they burn

Photo, posted April 6, 2017, courtesy of Bonnie Moreland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

La Niña has arrived

February 26, 2025 By EarthWise Leave a Comment

After seven months of waiting following the end of the recent El Niño condition, La Niña finally showed up in the eastern Pacific Ocean in early December.

El Niño and La Niña are climate patterns in the Pacific Ocean that can affect weather worldwide. Normally, trade winds in the Pacific blow west along the equator, taking warm water from South America towards Asia. To replace the warm water, cold water rises from the depths. During El Niño, trade winds weaken and warm water is pushed back east, toward the west coast of the Americas. As a result, areas in the northern U.S. and Canada are dryer and warmer than usual.

During La Niña, trade winds are stronger than usual, pushing more warm water toward Asia. This results in more upwelling of cooler water from the depths. This tends to lead to drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than normal in the South and cooler than normal in the North.

According to the report published in January by NOAA, the La Niña that has arrived is not a particularly strong one. Sea surface temperatures are only about 1.3 degrees Fahrenheit below average in the tropical Pacific. The report also suggests that the La Niña condition may not stick around very long.

The El Niño-Southern Oscillation phenomenon adds a natural source of year-to-year variability in global temperatures. The presence of La Niña for at least part of this year may temporarily keep the lid on rapidly climbing global temperatures.

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La Niña Is Here

Photo, posted November 23, 2011, courtesy of NASA Goddard Space Flight Center via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Megadroughts

February 24, 2025 By EarthWise Leave a Comment

A new study by Swiss and Austrian scientists has found that persistent multi-year droughts have become increasingly common since 1980 and will continue to proliferate as the climate warms.

There are multiple examples in recent years in places ranging from California to Mongolia to Australia. Fifteen years of persistent megadrought in Chile have nearly dried out the country’s water reserves and even affected Chile’s vital mining output. These multi-year droughts have triggered acute water crises in vulnerable regions around the world.

Droughts tend to only be noticed when they damage agriculture or visibly affect forests. An issue explored by the new study is whether megadroughts can be consistently identified and their impact on ecosystems understood.

The researchers analyzed global meteorological data and modeled droughts over a forty-year period beginning in 1980. They found that multi-year droughts have become longer, more frequent, and more extreme, covering more land. Every year since 1980, drought-stricken areas have spread by an additional fifty thousand square kilometers on average, an area the size of Vermont and New Hampshire combined.

The trend of intensifying megadroughts is clearly leading to drier and browner ecosystems. Tropical forests can offset the effects of drought as long as they have enough water reserves. However, the long-term effects on the planet and its ecosystems remain largely unknown. Ultimately, long-term extreme water shortages will result in trees in tropical and boreal regions dying, causing long-term and possibly irreversible damage to these ecosystems.

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The Megadroughts Are upon Us

Photo, posted January 7, 2018, courtesy of Kathleen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon dioxide and wildfires

May 14, 2024 By EarthWise Leave a Comment

Climate change is a key factor in the increasing risk and extent of wildfires. Wildfires require the alignment of several factors, including humidity, temperature, and the lack of moisture in fuels, such as trees, shrubs, and grasses. All of these factors have strong ties to climate variability and climate change.

While the global surge in wildfires is often attributed to hotter and drier conditions, a new study by researchers from the University of California – Riverside has found that increasing levels of a greenhouse gas may be an even bigger factor.

According to the study, which was recently published in the journal Communications Earth & Environment, carbon dioxide is driving an increase in the severity and frequency of wildfires by fueling the growth of plants that become kindling.

Centuries of burning fossil fuels to produce heat, electricity and to power engines has added alarming amounts of carbon dioxide to the atmosphere. In fact, atmospheric CO2 levels are measuring more than 420 parts per million, which is a level not seen on earth for 14-16 million years.

Plants require carbon dioxide, along with sunlight and water, for photosynthesis. But rising levels of CO2 in the atmosphere are driving an increase in plant photosynthesis – an effect known as the carbon fertilization effect. This effect can make plants grow bigger and faster.

Warming and drying are important fire factors. These are the conditions that make the extra plant mass more flammable. But the study found that the increase in fires during hotter seasons is driven by the CO2-fueled growth of plants.

The researchers hope their findings will urge policymakers to focus on reducing carbon dioxide levels in the atmosphere.

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CO2 worsens wildfires by helping plants grow

Current carbon dioxide levels last seen 14 million years ago

Photo, posted January 17, 2024, courtesy of Jennifer Myslivy, BLM Fire/NIFC via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Arctic Warming And Weather At Mid-Latitudes | Earth Wise

May 18, 2023 By EarthWise Leave a Comment

Some of the most striking images of climate change are those of melting glaciers in the Arctic and polar bears stranded on shrinking sea ice. The Arctic has been warming at a rate twice as fast as the global average. In recent years, there has been growing recognition of the Arctic’s role in driving extreme weather events in other parts of the world.

Winters in the midlatitude regions have seen more extreme weather events. The past winter saw record-breaking cold temperatures and snowfall in Japan, China, and Korea. Many parts of Eurasia and North America experienced severe cold snaps, with heavy snowfall and prolonged periods of subzero temperature. On the other hand, Europe saw its second warmest winter on record with record high temperatures in many places, much drier than normal conditions, and the closure of many ski resorts.

A study published in the journal Climate and Atmospheric Science by scientists from South Korea and the U.S. looked at various climate projection models as well as historic climate data to assess what is likely to happen to weather in the mid-latitudes as the Arctic continues to warm. Warmer Arctic Sea temperatures usually result in lower winter temperatures in East Asia and North America as ocean currents and the jet streams are altered.

The study shows that Arctic warming-triggered cold waves in the mid-latitudes are likely to persist in a warmer future, but that such events will become more difficult to predict. The study highlights the importance of continued efforts to better understand the interactions between Arctic warming and the climate of the midlatitudes. There need to be better ways to predict the extreme weather events that are likely to come.

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Gwangju Institute of Science and Technology Researchers Correlate Arctic Warming to Extreme Winter Weather in Midlatitude and Its Future

Photo, posted August 31, 2006, courtesy of Hillebrand / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Europe Is Warming Faster Than The Rest Of The Planet | Earth Wise

January 3, 2023 By EarthWise Leave a Comment

A new study by researchers at Stockholm University has found that the warming during the summer months in Europe has been much faster than the global average. The findings, published in the Journal of Geophysical Research Atmospheres, are that the climate across the European continent has become drier, particularly in southern Europe, leading to worse heat waves and an increased risk of fires.

Warming over land areas occurs much faster than over oceans. The global average warming to date is 1.6 degrees Celsius over land and 0.9 degrees over oceans. This means that the global emissions budget to keep warming below 1.5 degrees has already been used up over land. The new study in fact shows that the emissions budget to avoid 2 degrees of warming has already been exceeded over large parts of Europe during the summer half-year (April to September).

This accelerated warming in Europe has led to more frequent heat waves. These, in turn, increase the risk of fires, such as the devastating fires in southern Europe this past summer.

Southern Europe has been experiencing a positive feedback situation in which the ongoing warming has been amplified because of drier soil and decreased evaporation. Added to that, there has been less cloud coverage over large parts of Europe, probably as a result of less water vapor in the air.

The study also looked at the impact of aerosol particles on temperatures in Europe. As the amount of relatively short-lived aerosol particles has decreased with the reduction of coal-fired power plants, the temporary cooling effects of those particles partially masking the underlying warming trend have diminished. In contrast, carbon dioxide emissions stay in the atmosphere for centuries.

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Large parts of Europe are warming twice as fast as the planet on average

Photo, posted April 18, 2020, courtesy of Roman Ranniew via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Saving Giant Sequoias | Earth Wise

October 13, 2022 By EarthWise Leave a Comment

Last year, the KNP Complex Fire burning in Sequoia National Park drew global attention as the General Sherman, the world’s largest tree, was wrapped in tinfoil-like material in order to repel the flames from the fire. Hundreds of firefighters labored for weeks trying to save giant redwood trees. Despite these efforts, the U.S. Forest Service estimates that wildfires killed 13% to 19% of the world’s giant sequoias in 2020 and 2021.

This past July, the Washburn Fire burned through part of Yosemite’s Mariposa Grove and the giant sequoias there were surrounded by automated sprinklers trying to shelter them from the flames.

For a century, government agencies have worked to extinguish all natural wildfires and prohibited Native people in the region from lighting the fires they traditionally used to manage their lands. As a result, forests have grown far thicker with trees that can fuel fires. The Sierras are now home to more than three times as many trees as when they were managed by indigenous communities. But more than 100 million of those trees had died by 2016 because of drought.

Add to this massive amount of kindling the effects of climate change – a hotter and drier environment – and there is the perfect storm for megafires among the giant sequoias.

There is federal legislation pending that would provide resources for prescribed burning and other forms of active forest management. It is controversial. It has attracted support from the Nature Conservancy, the Save The Redwoods League, and others, but also opposition from more than 80 environmental groups.

What is not controversial is that the Giant Sequoias are in the midst of a crisis and urgent action is needed.

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In California, a Race to Save the World’s Largest Trees From Megafires

Photo, posted December 10, 2014, courtesy of Laura Camp via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildfires And Cancer Risk | Earth Wise

June 20, 2022 By EarthWise Leave a Comment

Hotter and drier conditions are leading to an increasing number of wildfires in North America and elsewhere around the globe. Scientists have linked the severe heat and drought that fuel these wildfires to climate change. As the climate continues to change, wildfires are projected to become more prevalent, more severe, and longer in duration.

According to a United Nations report released earlier this year, the Western U.S., northern Siberia, central India, and eastern Australia have already seen an uptick in wildfires. The likelihood of catastrophic wildfires globally could increase by a third by 2050 and more than 50% by the turn of the century.

According to a new study by researchers from McGill University, living near regions prone to wildfires may boost the risk of developing serious health issues. The study, which tracked more than two million Canadians over a period of 20 years, found a higher incidence of lung cancer and brain tumors in people exposed to wildfires. People living within 50 kilometers of wildfires during the past 10 years had a 10% higher incidence of brain tumors and a 4.9% higher incidence of lung cancer when compared to people living further away.

This study, which was recently published in The Lancet Planetary Health, is the first to examine how proximity to forest fires may influence cancer risk.

In addition to the impacts on air quality, wildfires also pollute aquatic, soil, and indoor environments. While some pollutants return to normal levels shortly after the fire, many others persist in the environment for long periods of time.

The research team notes that additional work is needed to develop more long-term estimates of the chronic health effects of wildfires.

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Exposure to wildfires increases risk of cancer

Climate change is causing more wildfires and governments are unprepared, says U.N.

Photo, posted August 17, 2020, courtesy of USFS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Atmosphere Is Thirstier | Earth Wise

May 9, 2022 By EarthWise Leave a Comment

The American West is in the throes of a two-decade-long drought. The climate there is getting warmer and drier, which has led to increasing demand for water resources from both humans and ecosystems. According to a new study by the Desert Research Institute and collaborators, the atmosphere across much of the U.S. is also demanding a greater share of water than it used to.

Evaporative demand, which is also called atmospheric thirst, is a measure of the potential loss of water from the earth’s surface up to the atmosphere. It is a function of temperature, humidity, wind speed, and solar radiation. The study, published in the Journal of Hydrometeorology, assessed trends in evaporative demand during a 40-year period from 1980-2020.

The study’s findings showed substantial increases in atmospheric thirst across much of the Western U.S. over that period, with the largest increases centered around the Rio Grande and Lower Colorado rivers. This is important because atmospheric thirst is a persistent force in pushing Western landscapes and water supplies toward drought.

The study found that, on average, increases in temperature were responsible for 57% of the changes observed in atmospheric thirst, humidity 26%, and the other factors playing lesser roles.

For farmers and other water users, increases in atmospheric thirst mean that, in the future, more water will be required to meet existing water needs. Crops already require more water than they did in the past and can be expected to require more water in the future. Over time, for every drop of precipitation that falls, less and less water is likely to drain into streams, wetlands, aquifers, or other water bodies.

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New study shows robust increases in atmospheric thirst across much of U.S. during past 40 years

Photo, posted August 9, 2007, courtesy of William Clifford via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving The Giant Sequoia | Earth Wise

April 22, 2021 By EarthWise Leave a Comment

Giant sequoia trees are some of the most remarkable living things on earth. They can live up to 3,000 years. The tallest specimens tower over 300 feet, but it is their girth that really sets them apart. They are usually 20 feet in diameter, and some are up to 35 feet across at the widest. The largest tree in the world by volume is the General Sherman tree, which has a volume of 52,508 cubic feet. At 2,100 years old, it weighs 2.7 million pounds and is not only the largest living tree, but also the largest living organism by volume on the planet.

Giant sequoias are incredibly hardy. To have survived thousands of years, the oldest of these trees have endured hungry animals, diseases, fires, snowstorms, El Niño events, years-long droughts, and the efforts of loggers during the 19th and 20th centuries.

In February, unusually high winds knocked down 15 giant sequoias in Yosemite National Park. While sequoias are amazingly adapted to their narrow range in California’s Western Sierras, it appears as though climate change is altering their habitat faster than the species can migrate or adapt. Shorter cold seasons have meant more rain instead of snow, leading to floods and mudslides in the winter. Fires are more likely with less snowpack. Hotter, drier summers put sequoias under greater stress.

Forest managers work to preserve existing groves through fire mitigation, supplementary water, and careful stewardship of young trees in existing groves. If these efforts are successful through the ensuing decades, climate change may be just one more thing the sequoias outlasted. But at least some conservationists are now considering planting a new generation of sequoias in colder, nearby habitats.

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To Save Giant Sequoia Trees, Maybe It’s Time to Plant Backups

Photo, posted June 8, 2008, courtesy of Joi Ito via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Forecasting A Bad Year For Carbon

March 11, 2019 By EarthWise Leave a Comment

Carbon dioxide levels in the atmosphere are higher than they have been for hundreds of thousands of years, and they continue to grow. The United Kingdom’s national meteorological service – known as the Met Office – issues annual predictions of global CO2 levels based in part on readings taken at the Mauna Loa observatory in Hawaii. Their forecast for this year is that there will be one of the largest rises in atmospheric carbon-dioxide concentration in the 62 years of measurements at Mauna Loa.

Since 1958, there has been a 30% increase in the concentration of carbon dioxide in the atmosphere. This has been caused by emissions from fossil fuels, deforestation and cement production. The increase would actually have been even larger if it were not for natural carbon sinks in the form of various ecosystems that soak up some of the excess CO2.

Weather patterns linked to year-by-year swings in Pacific Ocean temperatures are known to affect the uptake of carbon dioxide by land ecosystems. In years with a warmer tropical Pacific – such as El Niño years – many regions become warmer and drier, which limits the ability of plants to grow and to absorb CO2 . The opposite happens when the Pacific is cool, as was the case last year.

The Met Office predicts that the contribution of natural carbon sinks will be relatively weak, so the impact of human-caused emissions will be larger than last year. The predicted rise in atmospheric CO2 is 2.75 parts-per-million, which is among the highest rises on record. The forecast for the average carbon dioxide concentration is 411 ppm, with peak monthly averages reaching almost 415 ppm. With global emissions not really declining, the numbers just get higher and higher.

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Faster CO₂ rise expected in 2019

Photo, posted March 18, 2006, courtesy of Darin Marshall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Disastrous Year

February 5, 2019 By EarthWise Leave a Comment

The number and economic impact of natural disasters around the world have increased dramatically over the past 30 years. In dollar terms, the amount has actually more than doubled. While 2017 and especially 2011 hold the records for worldwide economic damage, 2018 was pretty disastrous in its own right, totaling at least $160 billion.

The year was dominated by costly wildfires in California and tropical storms in the United States and Asia. According to a recent report by the reinsurance company Munich Re, the Camp and Woolsey fires in California alone caused losses of $21.7 billion, $16.5 billion of which was insured.

Overall, insurance companies paid out $80 billion in damage claims from natural disasters last year. This was less than the $140 billion in 2017 but is still double the 30-year average.

Losses from wildfires have increased dramatically in recent years and summers continue to get hotter and dryer, a likely consequence of climate change. These mounting costs bring into question whether people can continue to build in high-risk wildfire areas without dramatic changes in materials and the aggressive use of other protective measures.

Twenty-nine natural disaster events in 2018 caused more than a billion dollars in damage each. Tropical storms including hurricanes Michael and Florence in the United States and three Asian typhoons caused $57 billion in damage.

A severe drought in Europe that set off major wildfires and caused agricultural losses caused $3.9 billion in losses. Only about $280 million of this damage was covered by insurance companies since farmers in Europe don’t typically purchase insurance against drought. For them, 2018 was truly a disastrous year.

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Natural Disasters Caused $160 Billion in Damage in 2018

Photo, posted July 26, 2018, courtesy of Bureau of Land Management California via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Your Children’s Yellowstone

January 25, 2019 By EarthWise Leave a Comment

Yellowstone National Park was the first national park in the US and according to some sources, the first in the world. It is the home of charismatic megafauna and stunning geysers that attract over four million visitors a year. It is the only place in the United States where bison and wolves can be seen in great numbers. And it is changing.

Over the next few decades of climate change, Yellowstone will quite likely see increased fire, less forest, expanding grasslands, shallower, warmer waterways, and more invasive plants. All these things will alter how and how many animals move through the landscape. Ecosystems are always changing, but climate change is transforming habitats so quickly that many plants and animals may not be able to make the transition at all.

Since 1948, the average annual temperature in the Greater Yellowstone ecosystem has gone up by 2 degrees Fahrenheit. On balance, winter is 10 days shorter and less cold. The Northern Rockies snowpack has fallen to its lowest level in eight centuries. Summers in the park are warmer, drier, and increasingly prone to fire.

Non-nutritious invasive plants like cheatgrass and desert madwort have replaced nutritious native plants. When plants like these take over, they suck moisture out of the ground early so that bison and elk cannot be sustained throughout the summer.

The behavior of elk and other animals is already changing, with many staying outside the park to nibble lawns and alfalfa fields. In turn, wolves go where the elk go. Forests and waterways are changing as well.

The rapid changes going on at Yellowstone mean that the park that our children and grandchildren will visit in the future is likely to be a very different one from the Yellowstone we remember.

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In Yellowstone National Park, warming has brought rapid changes.

Photo, posted September 7, 2016, courtesy of Mike Yang via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Hawaii

December 18, 2017 By EarthWise Leave a Comment

The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and seamounts in the North Pacific Ocean. The islands are a world-renowned vacation spot, known for their white-sand beaches, lush flora, and near perfect weather. But stormier days may be ahead.