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The warmer, greener Arctic and greenhouse gas

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About 15% of the Northern Hemisphere is covered by permafrost.  Permafrost is soil and sediment that has remained frozen for long periods of time, in some cases as much as 700,000 years.  It contains large amounts of dead biomass that has accumulated over millennia and hasn’t fully decomposed.  Therefore, permafrost is an immense carbon sink.

The Arctic is warming four times faster than the rest of the planet and, as a result, thawing permafrost is becoming a carbon source.  As warming continues, ice is melting, and vegetation is spreading.    A new study, published in Nature Climate Change, looked at the state of the Arctic and boreal north from the period 1990 until 2020.  The study found that although half of the Arctic region has been growing greener, only 12% of those green areas are actually taking up more carbon.  For one thing, the growth of forests means that there is more fuel for wildfires which are increasingly common.

A study of lakes in West Greenland found that thousands of crystal blue lakes have turned brown during record heat spells.  Runoff from melting permafrost made the lakes opaque killing off plankton that absorb carbon dioxide.  Meanwhile, plankton that release carbon dioxide multiplied.  So, these lakes went from being carbon sinks to being carbon sources.

As the northern latitudes warm, ice and permafrost are melting, vegetation is spreading, and the region is becoming a source of heat-trapping gas after having been a place where carbon has been locked away for thousands of years.  According to the Nature Climate Change study, roughly 40% of the Arctic is now a source of carbon dioxide.

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Warmer, Greener Arctic Becoming a Source of Heat-Trapping Gas

Photo, posted October 14, 2024, courtesy of Christoph Strässler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

La Niña has arrived

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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

Cold spells and global warming

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January saw some major bouts of subfreezing temperatures across much of North America and significant snowfall in places like Pensacola, Florida and New Orleans.  This spate of frigid weather undoubtedly prompted many people to question whether global warming is really happening.  But such cold spells quite likely are not happening in spite of global warming, but actually as a result of it.

The polar jet stream is a slim band of westerly winds that circles the Arctic.  It is formed where cold air from the north meets warmer air to the south.  As the planet warms, the Arctic has been heating up nearly four times faster than the rest of the planet, which narrows the difference in temperature between the northern air and southern air.  The result is that the jet stream is weaker and more meandering, which allows frigid air to reach further south.

The polar vortex is a whirling mass of cold air that extends across the Arctic.  It is stronger in the winter when the Northern Hemisphere leans away from the sun.  The polar jet stream normally holds on to the vortex and keeps it far to the north.  But when the jet stream gets wobbly, this mass of cold air can break out and travel south, even to places like Florida, Louisiana, and Texas.

The planet as a whole is warming, and the Arctic is warming even faster.  But there will still be plenty of ice, snow, and frigid air in the Arctic winter for decades to come.  As the behavior of the polar jet stream gets increasingly erratic, there may well be more frequent episodes of plunging temperatures in areas unaccustomed to them.

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Severe Cold Spells May Persist Because of Warming, Not in Spite of It

Photo, posted January 5, 2025, courtesy of Dermot O’Halloran via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Food, timber, and climate change

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The sights of coffee plantations in California and vineyards in Britain are becoming more common as the climate changes. But behind what sounds like a success story is a sobering one: climate change is shifting the regions suitable for growing food all around the world. 

According to a new study by researchers from the University of Cambridge, as crop growing shifts northwards, a squeeze will be put on the land needed to produce timber.  The timber these trees produce is used to make everything from paper and cardboard to furniture and buildings.

According to the study, which was recently published in the journal Nature Climate Change, more than 25% of existing forestry land – an area equivalent in size to India – will become more suitable for agriculture by the end of the century if climate change continues unabated.  Approximately 90% of this current forestry land is located in Canada, China, Russia, and the United States.    

Global timber production is worth more than $1.5 trillion every year.  Recent heat waves and wildfires have caused huge losses of timber forests around the world. 

According to the World Bank, the value of the global food system is estimated to be roughly $8 trillion annually.  Scientists expect climate change to cause some areas to become too hot for growing food, particularly in the tropics and southern Europe. 

With the global demand for food and the global demand for wood both projected to double by 2050, the increasing climate change-driven competition between the two is set to be an emerging issue in the coming decades. 

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Global timber supply threatened as climate change pushes cropland northwards

Do the costs of the global food system outweigh its monetary value?

Photo, posted October 24, 2018, courtesy of Bill Smith via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Svalbard is melting

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Svalbard is a Norwegian archipelago between mainland Norway and the North Pole. It is one of the world’s northernmost inhabited areas and is a popular attraction for tourists.  Svalbard is famous for rugged, remote terrain of glaciers and frozen tundra sheltering polar bears, Svalbard reindeer, and Arctic foxes. The Northern Lights are visible during winter, and its summer features the “midnight sun”—sunlight 24 hours a day.  It is the home of the Svalbard Global Seed Vault, which provides safe, free, and long-term storage of seed duplicates from all gene banks and nations around the world. 

Over half of Svalbard’s land area is covered with ice and accounts for about 6% of the planet’s glaciated area outside of Greenland and Antarctica.  But Svalbard is also one of the fastest-warming places on Earth.

It has suffered extreme episodes of melting this summer, brought on by exceptionally high air temperatures.  In late July and early August, temperatures hovered around 7 degrees Fahrenheit above average for this part of the Arctic Circle, causing snow and ice to rapidly melt.

According to scientists, Svalbard’s ice caps broke their all-time record for daily surface melt on July 23rd, shedding nearly half a foot of water equivalent that day, a rate five times larger than normal. 

On August 11th, the high temperature in Longyearbyen, Svalbard’s capital city, reached 68 degrees, the highest August temperature on record and 4 degrees above the previous monthly record.  Svalbard experienced its warmest summer on record in 2023.

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Svalbard Melts

Photo, posted September 21, 2016, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Farming the frozen north

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Agriculture is the primary cause of land-based biodiversity loss.  As the global population grows, agricultural production needs to keep pace.  Estimates are that production needs to double by 2050.  How this can be accomplished without doing further harm to the environment and biodiversity is extremely challenging.

Climate change adds further complications to the challenge.  As the climate warms in the middle latitudes, agricultural zones may need to shift northward to regions which have evolved to have more suitable climates.  This represents a very real threat to the wilderness areas of Canada, Russia, and Scandinavia.  These places represent a significant fraction of the world’s wilderness areas outside of Antarctica.

According to researchers at the University of Exeter in the UK, if the forces driving climate change are not diminished, over the next 40 years warming temperatures are expected to make more than 1 million square miles newly suitable for growing crops.  As cropland goes barren in areas that have warmed too much, northern wilderness could be turned over to farming.  The vital integrity of these valuable areas could be irreversibly lost.

The study, published in the journal Current Biology, also says that climate change will shrink the variety of crops that can be grown on 72% of the land that is currently farmed worldwide.  Given this situation along with the rising global population, it is essential that land be used more efficiently.  We can feed a larger population from the farmland we already have, but people need to reduce meat consumption, cut food waste, and grow crops suited to their local climate.

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Warming Could Make Northern Wilderness Ripe for Farming, Study Finds

Photo, posted September 7, 2016, courtesy of Scott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Disappearing snow crabs

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Alaska snow crabs are a cold-water species found off the coast of Alaska in the Bering, Beaufort, and Chukchi Seas. They are one of ten commercially-fished species in Alaskan waters. The perils of crab fishing in this region have been well documented for many years in the reality TV series Deadliest Catch.

Last year, officials in Alaska canceled the winter snow crab season for the first time ever due to a sharp population decline. While the number of juvenile snow crabs was at record highs just a few years earlier, approximately 90% of snow crabs mysteriously disappeared ahead of the 2021 season. 

This year, officials in Alaska have once again canceled the snow crab harvest season for the second year in a row, citing the overwhelming numbers of crabs – in the billions – missing from Alaskan waters. 

Scientists have suspected that the warming ocean temperatures triggered this snow crab population collapse.  But did the crabs move someplace else or die off?  According to a new study recently published by scientists at the National Oceanic and Atmospheric Administration, warmer ocean temperatures likely caused the snow crabs to starve to death.  The research team found a significant link between recent marine heat waves in the eastern Bering Sea and the sudden disappearance of the snow crabs that began showing up in surveys in 2021.

According to the study, warmer ocean water dramatically increases snow crabs’ caloric needs. But with the warmer water also disrupting much of the region’s food web, snow crabs had a hard time foraging for food and weren’t able to keep up.

Researchers expect the population may eventually find refuge in colder waters further north.

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Climate Change And Crabs

Billions of crabs went missing around Alaska

Photo, posted August 28, 2013, courtesy of Boris Kasimov via Flickr.

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Top Fish Predators And Climate Change | Earth Wise

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Climate change is taking its toll on forests, farms, freshwater sources, and the economy, but ocean ecosystems remain the epicenter of global warming.  In fact, oceans have absorbed more than 90% of the excess heat from greenhouse gas emissions since the 1970s.

As a result, many marine fish species are responding to ocean warming by relocating towards the poles.  According to new research recently published in the journal Science Advances, climate change is causing widespread habitat loss for some of the ocean’s top fish predators, driving these species northward.

The research team studied 12 species of highly migratory fish predators, including sharks, tuna, and billfish, such as marlin and swordfish, inhabiting the Northwest Atlantic Ocean and the Gulf of Mexico.  These two regions are undergoing rapid changes in sea surface temperatures, and are among the fastest warming ocean regions on earth.

The research, which was led by researchers from Woods Hole Oceanographic Institution in Massachusetts, with collaboration from San Diego State University, NOAA, and several other U.S. institutions, found that most species will encounter widespread habitat losses by 2100.  Some species could lose upwards of 70% of suitable habitat by that year.  Areas offshore of the Southeast United States and Mid-Atlantic coasts were identified as likely hotspots of multi-species habitat loss. 

According to the researchers, strategies for managing fish have historically been static. But marine systems need to be treated as dynamic and changing.  This study helps provide the scientific data needed for marine conservation and fisheries management efforts.

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Top fish predators could suffer wide loss of suitable habitat by 2100 due to climate change

Photo, posted March 18, 2015, courtesy of Kenneth Hagemeyer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

River Of Dust | Earth Wise               

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Every year, more than 100 million tons of dust blow out of North Africa.  Strong seasonal winds lift the dust from the Sahara Desert northward.  A few times a year, the winds from the south are strong and persistent enough to drive the dust all the way to Europe.

On March 15, a large plume of Saharan dust blew out of North Africa and crossed the Mediterranean into Western Europe.  European cities were blanketed with the dust, degrading their air quality, and turning skies orange.  Alpine ski slopes were stained with the dust.

These dust events are associated with so-called atmospheric rivers that arise from storms.  Such rivers usually bring extreme moisture but can also carry dust.  Over the past 40 years, nearly 80% of atmospheric rivers over northwestern Africa have led to extreme dust events over Europe.  The March 15 event was associated with Storm Celia, a powerful system that brought strong winds, rain, sleet, hail, and snow to the Canary Islands.

Atmospheric dust plays a major role in climate and biological systems.  The dust absorbs and reflects solar energy and also fertilizes ocean ecosystems with iron and other minerals.

The climate effects of dust are complicated.  Dust can decrease the amount of sunlight reaching the surface, affect cloud formation, and decrease temperatures.  But dust also darkens the snowpack, leading to more rapid snowmelt.  A 2021 dust event resulted in a rapid melt of Alpine snow, reducing its depth by half in less than a month.

The effects of this year’s dust event are not yet known, but this atmospheric river associated with Storm Celia appeared to carry less water and more dust compared with the 2021 event.

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An Atmospheric River of Dust

Photo, posted December 2, 2019, courtesy of Catherine Poh Huay Tan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Polar Bears And Melting Sea Ice | Earth Wise

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Climate change poses a major threat to polar bear survival.  The polar bear, whose native range lies largely within the Arctic Circle, depends on sea ice for nearly all of its lifecycle functions.  And rising temperatures are causing this sea ice to disappear.

Climate change-driven sea ice loss is the primary threat to the future of this iconic species.  In fact, polar bears were the first animal listed as endangered because of the forecasted impacts of climate change.   

Melting sea ice as a result of climate change continues to plague polar bear survival.  According to a new study by researchers from Washington State University, polar bears in the Beaufort Sea have had to travel far outside their traditional arctic hunting grounds in recent years for food.  This has contributed to an almost 30% decrease in their population. 

Researchers used satellite tracking data to analyze the movement patterns of female polar bears from 1986-2016 in the Beaufort Sea area north of Alaska.  Over the last two decades, they found that polar bears are having to travel farther north of their traditional hunting grounds on the continental shelf to remain on their receding sea ice habitat.

The research team also found that around 20% of the polar bear population in the Beaufort Sea is foregoing its traditional sea ice hunting grounds altogether in the summer and fall.  Instead, these bears are moving inland in search of food.  

Scientists estimate that 800 or so polar bears remain in the southern Beaufort Sea.  Curbing global greenhouse gas emissions in order to protect polar bear habitat may be the only way to help these animals survive. 

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Melting sea ice forces polar bears to travel farther for food

Photo, posted September 27, 2015, courtesy of Anita Ritenour via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Armadillos Heading North | Earth Wise

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Armadillos are small mammals known for their unique armor-like shell and their digging habits.  There are 21 species, primarily native to South America.  Some species have expanded northward due to their rapid breeding cycle, adaptability, and reduced number of predators.  Only one species – the nine-banded armadillo – is found in the United States.  In fact, it is the official small mammal of the state of Texas.

Over time, armadillos have expanded their range to states in the Deep South.  More recently, the animals have been pushing further north.  Milder winters in the changing climate have allowed them to inhabit new areas, including parts of the Blue Ridge Mountains. They were first sighted in North Carolina in 2007 and their numbers have recently been growing in the western half of the state.

There are now armadillos as far north as Missouri, Nebraska, and Iowa, and there is little to halt their further advance.  They are able to hold their breath for six minutes at a time, so they can cross rivers by walking along the bottom or by inflating their intestines and floating across the top.  Their hard shell provides protection from predators.  They reproduce prolifically.  Females give birth to quadruplets multiple times over the course of their 12-15-year lifespan.

Armadillos are fun to look at, but they are a nuisance where people live.  They are prone to digging holes in lawns.  In parts of North Carolina, some people have placed bounties on the animals.  They are difficult to trap and there aren’t common repellents for them.  As the climate continues to warm, it is only a matter of time before the range of armadillos expands into other states.

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Armadillos Advance Northward As Temperatures Rise

Photo, posted May 2, 2017, courtesy of Gail Hampshire via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Right Whales And The Warming Atlantic | Earth Wise

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The warming of the Atlantic Ocean has driven the critically endangered North Atlantic right whale population from its traditional and protected habitat.  This has exposed the whales to more lethal ship collisions, increased entanglements with commercial fishing gear, and greatly reduced calving rates.

Since 2010, the calving rate has declined, and the right whale population has dropped by an estimated 26%.  Ten years ago, there were about 500 North Atlantic right whales; now there are an estimated 356.

These are some of the best studied whales in the oceans; scientists basically recognize each individual whale and when they are the victims of ship collisions or fishing entanglements, it is easy to identify which animal was killed.

Because of the warming climate, the Atlantic Meridian Overturning Circulation – an important system of surface and deep currents – has slowed down, causing the Gulf Stream to move north.  This has injected warmer and saltier water into the Gulf of Maine.  The warming Gulf of Maine has reduced the abundance of copepods, tiny crustations that are the favorite snack of right whales.   This has reduced whale calving rates and forced the whales to move north to the cooler waters of the Gulf of St. Lawrence.

For the past 6 years, more and more right whales have been observed feeding in the Gulf of St. Lawrence, where there were no protections in place to prevent ship strikes and fishing gear entanglement.  In 2017 alone, 17 right whale deaths were confirmed.

According to a recent report from Cornell University and the University of South Carolina, unless its management is improved, right whale populations will decline and potentially become extinct in the coming decades.

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Warming Atlantic forces whales into new habitats, danger

Photo, posted December 8, 2016, courtesy of Sea to Shore Alliance/NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Butterflies And Moths In A Changing World | Earth Wise

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Extinction is a part of life.  Plant and animal species disappear all the time.  In fact, approximately 98% of all the organisms that have ever existed on planet earth are now extinct. Earth’s so-called ‘normal’ rate of extinction is thought to be somewhere between 0.1 and 1 species per 10,000 species per 100 years. 

But anthropogenic climate change is bringing about rapid change in nature. Put more simply, human activity is killing nature at an unprecedented rate.  According to many scientists, the earth’s sixth mass extinction has already begun. Mass extinctions are defined as times when the Earth loses more than 75% of its species in a geologically short interval.

The changing climate puts immense pressure on species for change.  According to a new study by researchers from the University of Helsinki and the Finnish Environment Institute, the few butterfly and moth species capable of adjusting to the changing climate by moving up their flight period and moving further north have fared the best.

In Finland, researchers compared temporal shifts in the flight period and spatial shifts in the northern range boundary of 289 moth and butterfly species, as well as changes in abundance over a roughly 20-year period.

They found that about 45% of species that either moved northward or advanced their flight period fared much better than the roughly 40% of species that did not respond in either way.  On average, the populations of these poorly responding species declined.  But the 15% of species that did both had the largest increase in abundance. 

The ability to adapt to a changing climate is going to be vital for species survival. 

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Butterflies and moths have difficulty adjusting to a rapidly changing climate

What is mass extinction and are we facing a sixth one?

Photo, posted August 16, 2017, courtesy of Tero Laakso via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Giant Breakaway Iceberg | Earth Wise

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Scientists have been closely monitoring multiple cracks and chasms that have formed in the 500-foot-thick Brunt Ice Shelf in Antarctica over the past few years.  In late 2019, a new crack was spotted in a portion of the shelf north of an area known as the McDonald Ice Rumples.  The rift was monitored by satellite imaging and was seen by February as moving about 15 feet a day.

In the early hours of February 26th, the crack widened rapidly before finally breaking free from the rest of the floating ice shelf.  News reports around the world have described the massive 500-square-mile iceberg by comparing it to the size of well-known cities:  1.5 times the size of greater Paris, 10 times the size of San Francisco, twice the size of Chicago, nearly the size of Greater London, and so on.

Antarctica is known for churning out some enormous bergs.  The new iceberg, which has been named A-74, is huge, but doesn’t compare to the iceberg A-68 that calved from the Larson C Ice Shelf in 2017.  That one was almost five times larger.

The calving of A-74 does not pose a threat to the presently unmanned British Antarctic Survey’s Halley VI Research Station, which was repositioned in 2017 to a more secure location after the ice shelf was deemed to be unsafe.  The section where the station now sits is still holding on, but when it eventually breaks, it will likely create a berg nearly 700 square miles in size.

It remains to be seen what will become of the new iceberg.  Most likely, it will eventually get caught up in the Weddell Gyre, a clockwise-rotating ocean flow in the Southern Ocean that covers an area more than half the size of the US.

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Breakup at Brunt

Photo, posted October 27, 2016, courtesy of NASA/Nathan Kurtz 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.

Scandinavian Wine

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The warming climate is creating some unexpected entrepreneurial opportunities.  Many places that have traditionally dominated the wine industry are starting to be worried that the local climates that made them ideal for vineyards are changing and becoming much less ideal.  On the other hand, places where wine-making was regarded as a losing proposition are becoming much more hospitable.  A prime example is Scandinavia.

Nordic vintners are increasingly convinced that they can develop thriving commercial operations in what used to be places that are too cold for successful wine-making.

Denmark now has 90 commercial vineyards, up from just two 15 years ago.  Forty vineyards have sprung up in Sweden.  About a dozen vineyards are now operating as far north as Norway.

Many of these Nordic vineyards are in the startup stage and are tiny compared with the established wineries of Europe.  Europe has 10 million acres of vineyards, which is enough to cover almost the entire country of Denmark.  At the moment, there are only about 1,000 acres of vineyards in Denmark and Sweden.

But, looking forward, Scandinavia’s climate is forecast to be more like northern France, as regional temperatures climb as much as 10 degrees Fahrenheit.  Over the past decade, warming has produced milder winters, a longer growing season, and even a small but rising number of award-winning Scandinavian wines.

Meanwhile, traditional wine-growing regions are also dealing with climate change.  Winemakers in France, for example, are experimenting with grapes from warmer countries like Tunisia to see if they can retain the tastes and yields that are the basis of a multibillion-dollar wine industry.  Spanish and Italian winemakers are planting grapes higher up on mountainsides or on shaded north-facing slopes to preserve the quality of their wine.

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Scandinavian Wine? A Warming Climate Tempts Entrepreneurs

Photo, posted August 24, 2019, courtesy of Ron Reiring via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Refugee Corals

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As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrived.  As a result, drifting coral larvae are settling and growing in new regions.

According to new research in the journal Marine Ecology Progress Series, the number of young corals on tropical reefs has declined by 85% over the past 40 years.  At the same time, the numbers on subtropical reefs has doubled.

Only certain types of coral can reach these new subtropical locations.  That depends on how far the microscopic larvae can swim and drift on currents before they exhaust their limited fat stores.  Thus, the reef ecosystems that develop have new blends of species that have previously never coexisted.  It is not clear how long it will take for the new systems to reach equilibrium.

Coral reefs are complicated systems that depend on the interplay between species to enable their healthy functioning.  Apart from the corals themselves, there are the coraline algae that symbiotically coexist with them.  How all of this will play out in these evolving ecosystems is unknown.

In the meantime, the research has found that these refugee corals are settling at latitudes up to 35 degrees both north and south of the equator.  It is no longer so clear what constitute native species in the reefs.  It remains to be seen whether new reefs in subtropical oceans can support the incredible biodiversity seen in tropical reefs.  But ultimately, these changing ecosystems could potentially bring new resources and opportunities, such as fishing and tourism, to places where they never existed before.

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Coral Reefs Shifting Away from Equatorial Waters

Photo, posted March 22, 2011, courtesy of Simone Lovati via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shifting Ecosystems

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The Great Plains ecosystem has been shifting northward over the past fifty years, driven by climate change, wildfire suppression, energy development, land use changes, and urbanization.  The ecosystem is an area historically rich with grasslands and shrub steppe and is prime habitat for grassland birds.

According to a recent study published in the journal Nature Climate Change, the northernmost ecosystem boundary of the Great Plains has moved more than 365 miles north since 1970, amounting to about 8 miles a year.  The region’s southernmost ecosystem boundary has shifted 160 miles north, or about 4 miles a year.

The study used bird distribution data as an indicator of shifting ecosystem boundaries.  The researchers analyzed 46 years of data for 400 bird species across a 250-mile-wide strip stretching from Texas to North Dakota.  They tracked how the birds’ distributions changed as a measure of how these ecosystems were shifting.

While climate change has been a major driver of these ecosystem shifts since the 1970s, several other factors such as wildfire trends, land use changes, and invasion of tree species into grassland habitat have also played a role.  Like most things in ecological systems, the changes are likely to have multiple causes.  One cannot really separate causes like tree invasions, warming climate, and wildfires, as they are all interrelated.

Using bird distribution patterns for tracking ecosystem shifts could be a useful tool for scientists and land managers in the coming decades to give them an early warning of how habitats are changing in response to rising global temperatures and therefore allow them to take action to protect vulnerable species.

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Great Plains’ Ecosystems Have Shifted 365 Miles Northward Since 1970

Photo, posted March 24, 2017, courtesy of Rick Bohn / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dangerous Cities For Migrating Birds

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Billions of birds migrate north in the spring and south in the fall.  The majority of them fly at night. But as they pass over large cities, the birds can become disoriented by bright artificial light – so-called light pollution, causing them to crash into buildings or windows.

Researchers estimate that 600 million birds die from building collisions in the United States every year.  Now, a new paper from researchers at Cornell University reveals which metropolitan areas are most dangerous for birds and why.

The researchers ranked cities where, as a result of geography and exposure to light pollution, birds are at the greatest risk of becoming attracted to and disoriented by lights and crashing into buildings. They combined light pollution levels with bird density data in order to make their calculations.  Their paper was recently published in the journal Frontiers in Ecology and the Environment.    

Chicago, Houston, and Dallas finished as the three most dangerous cities for migrating birds.  While migration routes vary depending on the season, these three cities still topped all others during both the spring and fall migrations due to their size and geographic positioning in the heart of North America’s most trafficked aerial corridors.  

Audubon’s Lights Out program is one of several national efforts encouraging cities to reduce light pollution, particularly on heavy migration nights, in order to reduce bird mortality. 

But homeowners need to do their part as well since an estimated quarter-million birds die from collisions with residential houses every year.  The suggestion to cities and homeowners alike is the same:  If you don’t need the lights, turn them off. 

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Chicago tops list of most dangerous cities for migrating birds

Photo, posted May 18, 2017, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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