Earth Wise

A look at our changing environment.

You are here: Home / Archives for migration

migration

Climate change and the global food supply

By Leave a Comment

One of the most troubling aspects of global climate change is its potential to severely disrupt the production, distribution, and quality of food. While food security is already challenged by many factors, including population growth, poverty, and changing eating habits, climate change intensifies these issues by altering weather patterns, causing more frequent droughts, floods, and extreme temperatures that damage crops and reduce yields. 

These shifts not only threaten agricultural productivity and increase food prices, but they also impact water resources, pests, and disease dynamics, further destabilizing food systems and exacerbating vulnerabilities, particularly in regions already facing food insecurity.

According to a new paper, which was co-authored by 21 scientists from 9 different countries, climate change will cause widespread food shortages, leading to famine, mass migration, and global instability, unless swift action is taken to develop climate-resilient crops.

Adding to the urgency is the fact that agriculture itself also contributes approximately 30% of global greenhouse gas emissions, creating a vicious feedback loop that threatens to further accelerate global climate change.

The research, which was recently published in the journal Trends in Plant Science, outlines five key recommendations to address this crisis: Study plants in real-world conditions, strengthen partnerships with farmers, streamline regulations for faster innovation, build public trust in new technologies, and create global research initiatives that unite scientists from developed and developing nations to share resources and expertise.

**********

Web Links

Climate Change Threatens Global Food Supply: Scientists Call for Urgent Action

Photo, posted September 21, 2014, courtesy of Peter via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate change and fish migration

By Leave a Comment

The warming climate is changing the distribution of fish species.  Researchers at the University of Adelaide in Australia have observed that tropical fish species are moving into temperate Australian waters.

The Eastern Australian Current is strengthening as the climate warms and larvae of tropical fish are getting caught in the current and moving into more temperate regions.  These larvae would not normally survive in the cooler Australian ocean water, but the warming current keeps the baby fish warm and increases their chances for survival.  The fish migration observed in the study is an ongoing process that has strengthened in the last few decades due to ocean warming.

The novel populations of tropical fish in these temperate ecosystems are not having much impact at the present time, but they may do so in the future.  The water is still cooler than the fishes’ natural environment and therefore they do not grow to their maximum size.  As a result, they don’t represent stiff competition for the native species – at least not yet.

As the ocean temperatures continue to rise, these tropical species will eventually grow to their full size and their diets will overlap more and more with those of temperate fish species.  Tropical herbivores tend to overgraze temperate kelp while the impact of tropical fish that eat invertebrates is less well understood.  Tropical fish with varied diets are the most successful invaders.  The ultimate effects on temperate ecosystems remain to be seen but survival may become difficult for the native fish in rapidly warming temperate ocean environments.

**********

Web Links

Tropical fish are invading Australian ocean water

Photo, posted March 28, 2017, courtesy of Ryan McMinds via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Major species turnover forecasted for North American cities

By Leave a Comment

Climate change affects animal species in many ways.  It induces habitat loss, disrupts migration and breeding patterns, threatens marine life, and facilitates an increased spread of disease.  It may also affect where animals can be found in the future. 

According to a new study led by researchers from the University of Toronto Mississauga and Apex Resource Management Solutions in Canada, climate change may dramatically affect the animal species observed in North American cities by the end of the century.

The researchers used species distribution data combined with machine learning to study the impact of human-caused climate change on more than 2,000 animal species historically found in the 60 most populous North American cities. 

According to the research team, changes in biodiversity are brewing for almost every city it studied by the year 2100.  In fact, cities with a rich history of biodiversity are predicted to have the largest declines and fewest gains in species. Cooler and wetter cities like Quebec, Ottawa, Winnipeg, Kansas City, and Omaha are expected to welcome the most new species.  Warmer cities with higher precipitation – like cities in coastal California – are projected to lose the most species. 

More than 95% of bird and insect species are predicted to experience a change in the number of cities they call home.  Canines, most amphibians, and aquatic birds are expected to experience the greatest losses.  Toads, turtles, mice and pelicans are projected to become more common overall. 

The researchers hope their findings will encourage more efforts to protect biodiversity.

**********

Web Links

North American cities may see a major species turnover by the end of the century

Photo, posted September 29, 2013, courtesy of Jonathan Kriz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Confusion about monarch butterflies

By Leave a Comment

For years, we have heard that the iconic monarch butterfly is in great peril.  Monarchs east of the Rocky Mountains undertake a 4-generation, 3,000-mile migration in late summer to their winter home in central Mexico.  Since the 1990s, the overwintering monarch colonies began a steep decline causing scientists to fear for the sustainability of the species.  Trying to help, ordinary citizens have been planting milkweed – the food for the caterpillars – and have been rearing eggs and caterpillars on their porches and releasing adult butterflies.

A number of recent studies have rocked the world of monarch science.  A growing group of scientists now believe that monarchs are not in fact imperiled and that the home rearing and commercial breeding of monarchs is actually a major threat to the butterfly.

According to a comprehensive 2022 study, there has been no sharp decline in Eastern monarch populations across their summer breeding range.  The long-term declines in winter colony sizes are real but do not appear to be affecting the collective breeding population of Eastern monarchs. 

An undisputed major threat to monarchs is a parasite known as OE, which weakens butterflies and also makes it unlikely for them to complete migrations.  It turns out that overcrowding of butterflies resulting from the efforts of backyard and commercial breeders is increasing the spread of the disease.  The butterflies are in need of social distancing.

Monarch scientists are split into two camps.  One group calls for the protection of the butterfly under the Endangered Species Act.  The other says that what monarchs most need is for us to leave them alone.  It is a confusing situation.

**********

Web Links

Rethinking Monarchs: Does the Beloved Butterfly Need Our Help?

Photo, posted October 1, 2021, courtesy of Renee Grayson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wind turbines and bats

By Leave a Comment

Collisions with wind turbines are one of the leading causes of bat mortality in North America and Europe.  Most bat fatalities are caused by bats colliding with the rotating blades of wind turbines.  Fatalities are highest during autumn migration and on nights with low wind speeds.

According to a recent study, land-based wind turbines kill as many as 880,000 bats a year and are wiping out so many threatened bats that some species may become endangered unless preventative action is taken.

The big challenge is that bat conservation experts and scientists don’t know how to stop or reduce turbine collisions.  They don’t really know why bats are interacting with turbines to the extent that they are.  Do turbines attract bats?  Do turbines’ bright lights or just their silhouettes stimulate an attraction response?

The U.S. Department of Energy has awarded $8 million to five research centers to develop strategies for deterring bats from wind turbines. 

One of these is Bat Conservation International, which is an organization whose mission is to accelerate research to address knowledge gaps in bat ecology and behavior and develop technologies and industry methods to reduce fatality of bats at wind farms.  Among the approaches to be tested is limiting the use of nighttime lighting on wind farms to make migrating bats less likely to fly through blades. 

Another team at Boise State University is designing ultrasonic noisemakers to scare off bats. 

In announcing the new program, the Department of Energy states that wind energy must be appropriately and responsibly sited, which includes the protection of wildlife and their habitats.

**********

Web Links

Experts Seek to Spare Bats From Wind Turbine Collisions

Photo, posted January 10, 2013, courtesy of Tom Shockey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Why Are Insect Populations Declining? | Earth Wise

By Leave a Comment

The world is experiencing a decline in overall insect populations as well as a collapse in insect diversity.  A recent special issue of the journal Biology Letters discusses the major causes of this alarming trend.

According to the study, the primary causes of the worldwide decline in insect biomass are land-use intensification in the form of greater utilization for agriculture and building development, climate change, and the spread of invasive animal species as a result of human trade.

The study concludes that it is not just these factors that are driving the global disappearance of insects, but also that these three factors are interacting with each other.  For example, ecosystems that are deteriorated by humans are more susceptible to climate change and so are their insect communities.  Similarly, invasive species can establish themselves more easily in habitats damaged by human land-use and displace native species.  Many native insect species decline or go extinct while others – often invasive species – thrive and increase, leading to decreasing insect diversity.  Warming temperatures are making many locations undesirable for various insect species and they often cannot migrate to anyplace better.

Declining insect populations and diversity results in concomitant declines in plant species that depend on pollinators.  This in turn threatens the stability of entire ecosystems.

The researchers advocate for continued monitoring of insect diversity across many habitats and countries and propose the creation of a network of interconnected nature reserves such that species can move from one to another. 

We often think of insects as pests, but they are a crucial part of the world’s ecosystems.

**********

Web Links

The reasons why insect numbers are decreasing

Photo, posted April 17, 2011, courtesy of Dean Morley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Moving Endangered Species | Earth Wise

By Leave a Comment

People have intentionally or accidentally introduced numerous invasive species to habitats around the world.  At the same time, the planet’s wildlife is in a steep decline.  A recent study estimated that the populations of over 5,000 vertebrate species have declined by an average of nearly 70% since 1970.  A United Nations report warns that human activity has threatened as many as a million species with extinction.

With all of this as a background, there is climate change that is altering the habitats of the world’s species – warming lakes and oceans, turning forests into grasslands, tundra into woodland, and melting glaciers.  In response to these changes, living things are rearranging themselves, migrating to more hospitable locations.  But many species are just not capable of finding more suitable habitats on their own.

Conservationists are now increasingly considering the use of assisted migration. In some cases, when a species’ critical habitat has been irreversibly altered or destroyed, agencies are establishing experimental populations outside of the species’ historical range.  Such actions are often deemed extreme but may be increasingly necessary.

However, clear-cut cases are relatively rare.  More likely, it is a more difficult judgement call as to whether assisted migration is a good idea or is possibly a threat to the ecosystem of the species’ new location.  The relative dearth of assisted migration experiments is less likely a result of legal barriers than it is a lack of scientific and societal consensus on the practice. Scientists are now trying to develop risk-analysis frameworks that various agencies can use in considering potential assisted migration experiments. 

**********

Web Links

Last Resort: Moving Endangered Species in Order to Save Them

Photo, posted March 18, 2010, courtesy of Jean via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Building Resilient Food Systems | Earth Wise

By Leave a Comment

According to the United Nations and The World Bank, global hunger levels in 2021 surpassed the previous record set in 2020.  The organizations also found that acute food insecurity – defined as when a person’s inability to consume adequate food puts their lives or livelihoods in immediate danger – could continue to worsen this year in many countries around the world. 

According to a new study led by researchers from the University of Colorado Boulder, increased demand for water will be the biggest threat to food security during the next 20 years, followed closely by heat waves, droughts, income inequality, and political instability.  

The report, which was recently published in the journal One Earth, calls for increased collaboration to build a more resilient global food supply.  The impacts of conflict and climate change are already measured and studied around the world.  While these pressing threats are not new, the researchers found that better collaboration between these areas of research could fortify and strengthen global food security. 

In 2019, before the COVID-19 pandemic, the researchers surveyed 69 experts in various fields related to food security.  They found that many effects of climate change – such as unpredictable weather changes – could have the greatest negative impacts on food security.  The researchers also found that threats to food security from income inequality, global price shocks, and political instability and migration are highly likely during the next two decades.  More than half of the world’s food insecure populations also live in conflict-prone regions.

According to the research team, food security has never been a problem of production.  It’s a problem of distribution, access, and poverty, and can be exacerbated by conflict.   

**********

Web Links

Amid climate change and conflict, more resilient food systems a must, report shows

Photo, posted July 19, 2009, courtesy of Danumurthi Mahendra via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Some Good Monarch News | Earth Wise

By Leave a Comment

Eastern monarch butterflies spend their winter months in central Mexico.   Every spring, they embark on a lengthy, multigenerational migration that takes them into the United States and even into southern Canada, where they breed.  The butterflies go through several generations before they eventually migrate back to Mexico.

Twenty-five years ago, overwintering monarchs in Mexico blanketed nearly 45 acres of forest.  The acreage covered, which has been surveyed annually since 1993, is a rough indicator for the actual number of butterflies that survive the difficult migration process. In 2013, the monarchs occupied only 1.6 acres of Mexican forest.  The butterflies were deemed to be on the edge of extinction.

Last December, the monarch survey found 7 acres covered by the butterflies, an increase of 35% over the previous winter.  The population appears to be steadily rebounding, although the numbers are still substantially lower than the levels seen in the 1990s.

The butterflies are struggling with multiple problems.  There continues to be a lack of milkweed, the only food source for the caterpillars, in their breeding grounds along their migratory route.  More extreme weather driven by climate change is another challenge, and illegal logging in their overwintering habitat in Mexico has also become a threat.

After the butterfly population crashed in 2013, conservation efforts shifted into high gear with lots of milkweed planting in the US and Canada, and crackdowns on timber poachers in Mexico.

The remarkable multigenerational migration of monarchs is a delicate phenomenon that can be disrupted by many different things.  Eastern monarchs are still in serious danger, but the current trend seems to be positive.

**********

Web Links

Warming Trends: Butterflies Bounce Back, Growing Up Gay Amid High Plains Oil, Art Focuses on Plastic Production

Photo, posted August 12, 2021, courtesy of Paul VanDerWerf via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

American Robins And Climate Change | Earth Wise

By Leave a Comment

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.

**********

Web Links

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.

Bird Migration And Climate Change | Earth Wise

By Leave a Comment

A new study of bird migration shows the migration patterns are shifting as a result of climate change.   Researchers at Colorado State University, the University of Massachusetts, and the Cornell Lab of Ornithology, looked at the impacts of climate change on a continental scale.

The team looked at the nocturnal migratory behaviors of hundreds of species representing billions of birds using radar and other data.  They found that spring migrants are likely to pass certain stops earlier now than they would have 20 years ago.  Temperature and migration timing are closely aligned and the greatest changes in migration timing are occurring in regions warming most rapidly.  During the fall, shifts in migration were less apparent.

Migratory birds play an important role in ecosystems.  They consume insects, disperse seeds, and perform various other significant functions. Birds serve as critical metrics of the health of ecosystems.

Bird migration is a global phenomenon that can provide unique visibility into changes in the climate.  The ability to look at it on a global scale has only recently become practical as a result of big data technology and cloud computing.  The team was able to crunch the numbers for the study in 48 hours, a task that previously would have taken over a year of continuous computing.

The findings have implications for understanding future patterns of bird migration because birds depend on food and other resources as they travel.  As the climate changes, the timing of blooming vegetation or the emergence of insects may end up out of sync with the passage of migratory birds.  This could have negative consequences for the health of migratory birds.

**********

Web Links

Bird migration timing skewed by climate, new research finds

Photo, posted November 5, 2019, courtesy of Jerry Kirkhart via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Out-Migration And Reforestation

By Leave a Comment

A challenging global trend is that of deforestation in developing countries.  But there are places where the opposite trend is happening.  Nepal is one such place.

According to satellite imaging, in 1992 forest covered 26% of Nepal.  As of 2016, that number was 45%. 

To some extent, the forest regrowth was a result of policy changes from about three decades ago, when the government began removing management authority from bureaucrats and shifting it to local communities across the country.  This local management helped to reduce illegal logging and many local villages undertook tree-planting campaigns.

But perhaps a bigger factor at play is human migration.  In recent decades, millions of Nepalis have left the country to work in the Persian Gulf, Southeast Asia, and elsewhere.  The out-migrants wire money home and meanwhile, families left behind rely less on forest products or abandon farmland, aiding reforestation.  A 2018 study showed that the areas with the highest out-migration experience, on average, had the most forest recovery.

Globally, migration has important impacts on forests, but not always positive ones.  In many countries, forests seem to recover as people leave rural areas to work elsewhere.  El Salvador, for example, has seen a rebound of its forests as many of its rural residents move to cities or even to the United States. But in Guatemala and Nicaragua, the return of migrants bringing money they have earned overseas has led to an expansion of cattle ranching that has harmed forests.

The global relationship between migration and forests is a complicated one that depends on whether the migration is one-way or “circular” (meaning that the migrants eventually return) and how returning migrants make use of their earnings from abroad.

**********

Web Links

In Nepal, Out-Migration Is Helping Fuel a Forest Resurgence

Photo, posted September 30, 2018, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Disease On Coral Reefs

By Leave a Comment

The warming oceans have led to bleaching events in coral reefs around the world, but bleaching is not the only problem corals face.  Disease outbreaks are also becoming more frequent, severe, and widespread.

Many factors are contributing to the problem, including pollution and nitrogen runoff from fertilizers and coastal sewer and septic systems.  However, the key culprit is likely the steadily increasing ocean temperatures, which are the cause of coral bleaching.  Elevated water temperatures can cause coral polyps to expel the algae that sustains them and gives them color. 

According to scientists, bleaching makes corals more susceptible to illness.  In the Caribbean, a coral disease hotspot, about 80% of coral cover has disappeared, largely from outbreaks of “white band disease”, so called because of a white band of dead tissue that forms in affected corals.  Two crucial reef-building species, elkhorn and staghorn coral, are now nearing extinction in the regions.  The reef extending along the Florida coastline is the third largest reef ecosystem in the world and nearly 35% of it has been lost to disease.

Estimates are that disease outbreaks have wiped out at least 6% of the corals on the Great Barrier Reef in Australia.  In that region, diseases are more prevalent in areas where corals were damaged by fishing and other human activity because wounded coral provides an entry point for pathogens and bacteria.

In the face of climate change and mounting disease outbreaks, scientists are scrambling for solutions to stave off catastrophe.  Assisting the migration of hardier coral species and breeding so-called “super corals” are among the strategies being pursued.  It is unknown whether these and other forms of intervention can be used on a wide enough scale to really make a difference.

**********

Web Links

As Disease Ravages Coral Reefs, Scientists Scramble for Solutions

Photo, posted November 29, 2012, courtesy of Robert Linsdell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Return Of The Bald Ibis

By 1 Comment

The northern bald ibis, also known as the waldrapp, is a strange-looking bird with a long, curved beak, a naked head, and feathers that point straight into the air like a Mohawk haircut.  In former centuries, it occurred widely in northern and eastern Africa, Asia Minor, Arabia, and parts of Europe.  The ancient Egyptians considered it to be an afterworld divinity and its likeness can be seen in hieroglyphs dating back thousands of years.

[Read more…] about The Return Of The Bald Ibis

North Atlantic Right Whales

By Leave a Comment

North Atlantic right whales are one of the rarest marine mammals in the world.  In fact, according to the National Oceanic and Atmospheric Administration, there are only about 450 of the whales left.  Measuring approximately 50 feet long and weighing close to 100,000 pounds, North Atlantic right whales are now more critically endangered than mountain gorillas, black rhinos, and giant pandas.

[Read more…] about North Atlantic Right Whales

Air Pollution Shortens Lives

By Leave a Comment

Globally, an estimated 4.5 billion people are exposed to particulate air pollution levels that are at least twice that of what the World Health Organization considers safe.  But the impact that sustained exposure to air pollution has on a person’s life expectancy has remained a frustratingly unanswered question.  That is until now.

[Read more…] about Air Pollution Shortens Lives

The Monarch Highway

By

We have talked about the monarch butterfly on a number of occasions.  The population of these iconic orange and black butterflies in North America has plummeted from 1 billion to 33 million over the past 20 years.  People have undertaken a variety of efforts to try to save the species but now a major project to restore the dwindling habitat of the monarch is underway.

[Read more…] about The Monarch Highway

WAMC Northeast Public Radio

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