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Oxygen Loss In Lakes | Earth Wise

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Researchers from Cornell University and Rensselaer Polytechnic Institute have found that the continual warming in the world over the past 25 years has been reducing the amount of oxygen in many lakes.

Data from more than 400 lakes – mostly in the United States – shows that lakes with dissolved oxygen losses strongly outnumber those with gains.  Overall, the researchers found that the amount of low oxygen water is increasing by 0.9% to 1.7% per decade on average  and the volume of lake water lacking oxygen has increased by more than 50% from 25 years ago.

In the summer, lake surfaces may be about 70 degrees while the lake bottom may be about 40 degrees.  The colder water is denser than the warmer water which causes resistance to the layers mixing.  It is akin to having oil and vinegar in a cruet.  This is known as stratification.   The result is that oxygen from the atmosphere is prevented from replenishing dissolved oxygen in deep waters.  This is a normal seasonal phenomenon.

However, with winter ending sooner than it used to, seasonal stratification is starting earlier and ending later. As warming continues, it is likely that there will be an increasing number of oxygen-depleted lakes in the future.

Oxygen deprivation in water can lead to hypoxia (low oxygen) and even anoxia (no oxygen), which have negative consequences for fish and other species.  Reducing oxygen in lake water can lead to buildup of methane.   Nutrients from agricultural runoff, released from unsettled lake sediment, increase the likelihood of harmful algal blooms.

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Warming climate prompts harmful oxygen loss in lakes

Photo, posted June 23, 2010, courtesy of Alexander Acker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Window | Earth Wise

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Researchers at Oxford University have developed a new adaptable smart window technology that has the potential of reducing the energy usage of the average home by a third.

The technology uses a spectrally tunable low-emissivity coating that can control the amount of heat that comes into a room without affecting the quality of the light that enters.

The thermal energy from the sun’s infrared rays is absorbed by the glass and then is re-emitted as heat.  That heat can either be used to warm the room using transparent electrical heaters embedded in the glass or can be reflected away to cool the room.  The windows can change according to seasonal needs.

The researchers built a prototype using a material called an active chalcogenide-based phase change material.  When it is cold, the infrared rays from the sunlight are harvested and used to heat the building.  When it is warm, the new glass can switch state to reflect the heat and reduce the need for air conditioning.  The active phase change material is adjustable so that the amount of heat absorbed or reflected can be tuned for precise temperature control.  There is essentially no effect on visible light passing through the window.  Current low-emissivity glass for windows can reduce heat transfer, but its properties cannot be altered according to seasonal needs.

The researchers estimate that using windows fitted with the new prototype glass – including the energy required to control the film – would save 20 to 34% in energy usage annually compared to double-glazed windows found in many modern homes.

A spinout company from Oxford called Bodle Technologies is collaborating with two existing industrial partners to develop the technology further.

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New adaptable smart window coating could help heat or cool a home and save energy

Photo, posted April 26, 2008, courtesy of Lima Andruska via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Spring Is Coming Earlier In Britain | Earth Wise

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The United Kingdom has some of the most detailed records of seasonal changes anywhere in the world.  Since the 18th century, observations of seasonal changes have been recorded by scientists, naturalists, amateur and professional gardeners, and organizations such as the Royal Meteorological Society.  Researchers at two British institutions have collected and collated these records into a database they call Nature’s Calendar, which currently has about 3.5 million records going back to 1736.

By analyzing more than 400,000 observations of 406 plant species in Nature’s Calendar, they found that the average first flowering date from 1987 to 2019 is a full month earlier than the average from 1753 to 1986.  The change correlates very well with rising global temperatures.

The ecological risks associated with earlier flowering times are high.  When plants flower too early, a late frost can kill them – a phenomenon most gardeners have experienced at some point or another.  Beyond that, plants, insects, birds, and other wildlife have co-evolved to be synchronized with plants in their development stages.  A certain plant flowers and attracts a certain kind of insect, which then attracts a particular kind of bird, and so on.  If plants get out of sync with the animals in the ecosystem and the animals can’t change their behavior quickly enough, it can lead to species collapse.

If global temperatures continue to increase at their current rate, spring in the UK could eventually start in February, creating serious problems for many of the species that inhabit forests, gardens, and farms.  The dangers of climate change are not just about extreme weather.

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UK plants flowering a month earlier due to climate change

Photo, posted February 1, 2012, courtesy of Mandy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfire Smoke And Dangerous Microbes | Earth Wise

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The worsening severity of wildfires across the globe is a major public health concern.  The pulmonary and cardiovascular consequences of wildfire smoke inhalation have been well researched and have been an increasing focus for officials in places like California, other western states, and Australia.  More recently, another public health concern has emerged related to the fact that wildfire smoke can carry microbes that cause infectious diseases.

A new analysis, published in the journal Science, points out that the risk of potential infection from airborne microbes has not been the subject of much research.

The fungus coccidioides, for example, becomes airborne when soils are disturbed by fire. When this fungus is inhaled, it can cause Valley fever, an infection with flu-like symptoms that sometimes progresses to pneumonia or meningitis.  Inhalation risk of these microbes is highest closest to fires, so coccidioidomycosis is listed as a professional risk for firefighters.

A recent study found an increase in cases of invasive mold infection, aspergilliosis, as well as cases of coccidioidomycosis at hospitals within 200 miles of major wildfires in California.

Wildfire smoke has been shown to carry airborne particles of fungal and bacterial cells, hitching a ride on water vapor or charred carbon, over thousands of miles.  Some microbes in soil appear to be tolerant of or even thrive under high temperatures following wildfires.

A multidisciplinary research collaboration is needed to better understand the relationship between microbes, wildfire, and public health.  Such knowledge is increasingly vital as severe wildfires become seasonal norms in parts of the world such as the United States and Australia.

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Wildfire Smoke Can Carry Dangerous Microbes Thousands of Miles, Scientists Warn

Photo, posted September 9, 2020, courtesy of Christopher Michel 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.

What’s On Nature’s Calendar? | Earth Wise

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The Inuit Calendar is based on six seasons defined by weather, ice, animal migration, daylight hours and the night sky.  All these variables are in flux according to Harvard Narwhal Biologist Dr. Martin Nweeia.  Last August in the high Canadian Arctic, at 72 degrees north latitude, temperatures were at an astounding 70 degrees during the day. In 2018, the same region at the same time of year, experienced one of the coldest August months in 15 years.  

Disappearing sea ice in Hudson Bay affects migration patterns of ice-dependent species like narwhal and beluga whales and now allows more shipping traffic which produces more marine noise pollution and the risk of an oil spill. As a natural resource, the Arctic has significant deposits of iron ore, gold, diamonds, phosphate, and bauxite, so cargo shipments are increasing yearly.  

The disappearance of caribou herds and altered migrations of other animals have also blurred the seasonal changes. Caribou numbers have decreased by more than half in the last two decades.  Narwhal populations are remaining steady but are experiencing migration shifts resulting in their appearance at new locations and their absence from traditional areas.  Even the timing of the migration has changed, shifting two weeks later from normal late summer – early fall patterns.  

The night sky, which has long had identifiable reference points for Inuit observers, is also changing causing speculation about changes in the magnetic field and a polar shift or flipping of the poles. The earth’s magnetic north has been shifting toward Siberia at an alarming 30 miles each year since 2015.  Every million years, it is estimated that the poles flip three times.  No one knows if or when it will happen again. That’s a calendar with some unexpected dates. 

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–Earth Wise acknowledges script contribution from Dr. Martin Nweeia of Harvard University.

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Migratory Tundra Caribou and Wild Reindeer

Earth’s magnetic field is acting up and geologists don’t know why

Photo, posted June 27, 2014, courtesy of the Bureau of Land Management via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Food Production And Climate Change

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According to a University of Oxford study recently published in the journal Science, food production is a major driver of climate change as it’s responsible for 26% of all greenhouse gas emissions.  But the research team found that the environmental impact of different foods varied greatly. 

Meat and other animal products are responsible for 58% of all food-related greenhouse gas emissions, despite only providing approximately one-fifth of the calories we consume.  The researchers found that beef and lamb in particular have the most damaging effect on the planet, responsible for half of all greenhouse gas emissions from animal agriculture. 

These findings echo recommendations from the Intergovernmental Panel on Climate Change about how individuals can reduce their carbon footprint through diet.  The IPCC suggests we consume less meat and dairy products, consume more locally-sourced seasonal foods, and throw less food in the trash.  

Avoiding meat and dairy products can reduce an individual’s carbon footprint from food by two-thirds.  The effects of doing so include everything from conserving water and preserving biodiversity to reducing pollution and deforestation. 

Interestingly, the same food can have major differences in terms of environmental impacts.  For example, beef raised on deforested land is responsible for 12 times as many greenhouse gas emissions as that raised on natural pastures.  But even the most climate-friendly meat options are still responsible for more greenhouse gas emissions than the highest-impact vegetable proteins, like beans and nuts. 

Big differences can also be made by avoiding chocolate and coffee produced from deforested lands.  

To learn more about the climate impact of your diet, follow the link to the ‘Climate Change Food Calculator’ on our website: Earth-Wise-Radio.org. 

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Reducing food’s environmental impacts through producers and consumers

Climate change food calculator

Photo, posted June 21, 2011, courtesy of USDA NRCS Montana via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Winter Outlook

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Each year around this time, the National Oceanic and Atmospheric Administration, or NOAA, releases its U.S. Winter Outlook that predicts overall weather trends around the country for the upcoming winter.  They produce these seasonal outlooks to help communities prepare for the weather that is likely to be forthcoming.

[Read more…] about Winter Outlook

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