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The Hottest Summer | Earth Wise

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It was a very rainy and relatively cool summer in much of New England as well as in New York’s Capital Region, where Earth Wise originates.  Despite that fact, according to NASA scientists, the summer of 2023 was the Earth’s hottest since global record keeping began in 1880.

The months of June, July, and August taken together were .41 degrees Fahrenheit warmer than any other summer on record as well as being 2.1 degrees warmer than the average summer between 1951 and 1980.

The record summer heat was marked by heatwaves in South America, Japan, Europe, and the US.  The heat exacerbated wildfires in Canada that dumped smoke across much of the northern tier of our country and also led to severe rainfall in Europe.  All sorts of temperature records were set in places across the globe.

According to NASA, exceptionally high sea surface temperatures, fueled in part by the reemergence of El Niño in the Pacific, were a major factor in the summer’s record warmth.

The record-breaking heat of this summer continues a long-term trend of warming.  Scientists around the world have been tracking the warming that is driven primarily by human-caused greenhouse gas emissions.  The combination of this background warming and the marine heatwaves set the stage for new temperature records.  The El Niño was enough to tip the scales. 

In the current environment, heat waves will last longer, be hotter, and be more punishing.  The atmosphere can hold more water producing hot and humid conditions that are harder for the human body to endure.

Scientists are expecting the biggest impacts of El Niño in the early parts of next year.  We can expect to see extreme weather of many kinds over the next year.

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NASA Announces Summer 2023 Hottest on Record

Photo, posted June 8, 2023, courtesy of Anthony Quintano via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Shrinking Birds | Earth Wise

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A new study by researchers at Yale University looks at the way bird morphology is changing in response to the warming climate.  As temperatures rise, birds’ bodies are growing smaller, but their wings are growing longer.

In the study, published in the Proceedings of the National Academy of Sciences, the scientists analyzed two independently collected datasets containing 40 years of morphology changes in 129 bird species comprising 52 migratory species in North America and 77 South American species.

In both datasets, similar changes were observed over the 40-year period.  The overall trend makes sense given that being smaller and having longer wings both would help birds to stay cool in warmer weather.  What was less obvious was that the changes to the birds were much greater among the smallest bird species.

One possible explanation is that smaller species tend to reproduce on a shorter time scale and therefore evolve more quickly.  However, the study found no link between generation length and the changes in body size.

Another possible explanation is that smaller species tend to have larger populations, which means there is a greater chance of having individuals with desirable new traits that can get passed on.  But the scientists found no link between population size and shifts in body size either.

At this point, it is unclear why smaller birds are shrinking more.  More research is needed to figure out why larger birds are slower to adapt to climate change.  In general, larger species of animals have an increased risk of extinction.  This new research suggests that larger body size exacerbates extinction risk by limiting the ability for birds to adapt to the changes we are making to the climate.

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Birds Are Shrinking as the Climate Warms — and Small Birds Are Shrinking Faster

Photo, posted October 30, 2018, courtesy of N. Lewis / National Park Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sinking Cities | Earth Wise

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Sea levels across the globe are rising as a result of the changing climate.  Two factors are largely responsible: the melting of ice sheets in the polar regions and the fact that as the oceans get warmer, the water in them expands.  

Estimates are that by 2050, there will be over 800 million people living in 570 cities that will be at risk from rising sea levels.   The rising waters can drown neighborhoods, put people’s lives at risk, and wreck entire economies.  Unless global emissions can be reduced sufficiently, sea levels will continue to rise.

A new study, published in the journal Nature Sustainability by Nanyang Technical University in Singapore in collaboration with the University of New Mexico, ETH Zurich, and NASA’s Jet Propulsion Lab, has focused on yet another aspect of the threat to coastal cities.  They have found that many densely populated coastal cities worldwide are even more vulnerable to sea level rise because much of their land is sinking. 

The researchers processed satellite images of 48 cities from 2014 to 2020 using a system called Interferometric Synthetic Aperture Radar.  They found that land subsidence varied on a neighborhood and even individual block level but across all the cities studied, there was a median sinking speed of 6/10” a year.  Some places had land that is sinking at 1.7” per year.  Meanwhile, the global mean sea-level rise is about .15” per year.

The increasing prevalence of industrial processes such as the extraction of groundwater, and oil and gas, along with the rapid construction of buildings and other urban infrastructure are leading to the sinking of the urban areas. 

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Rapid land sinking leaves global cities vulnerable to rising seas

Photo, posted October 24, 2015, courtesy of Jeffrey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Less Phytoplankton In The Gulf Of Maine | Earth Wise

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Phytoplankton, also known as microalgae, are the base of the marine food web and also play a key role in removing carbon dioxide from the air.  They are eaten by primary consumers like zooplankton, small fish, and crustaceans. 

Phytoplankton, like land plants, absorb carbon dioxide from the atmosphere and use photosynthesis to grow.  Then they become a food source for other organisms and ultimately for people who depend upon marine ecosystems.   If phytoplankton productivity is disrupted, there can be adverse effects on regional fisheries and the communities that depend on them.

The Gulf of Maine is becoming warmer and saltier, because of ocean currents pushing warm water into the gulf from the Northwest Atlantic.  These temperature and salinity changes have led to a significant decrease in the productivity of phytoplankton.   According to a new paper from scientists at Bigelow Laboratory of Ocean Sciences in Maine, phytoplankton are about 65% less productive in the gulf than they were 20 years ago.

The study’s results come from the analysis of the Gulf of Maine North Atlantic Time Series, a 23-year sampling program of the temperature, salinity, chemical, biological, and optical measurements of the gulf.  The scientists refer to what they describe as a giant windmill effect happening in the North Atlantic, which is changing the circulation of water coming into the Gulf of Maine.  In the past, inflows from the North Atlantic brought water from the Labrador Current, which made the gulf cooler and fresher.  The new circulation is making the water warmer and saltier.

These changes have significant implications for higher marine species, fisheries, the lobster industry, and other activities in the states that border the Gulf of Maine.

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NASA-funded Study: Gulf of Maine’s Phytoplankton Productivity Down 65%

Photo, posted November 15, 2015, courtesy of Paul VanDerWerf via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Atmosphere Is Thirstier | Earth Wise      

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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.

More Bleaching In The Great Barrier Reef | Earth Wise

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Australia’s Great Barrier Reef is an ecosystem that can be seen from space.  It has now suffered its 6th mass coral bleaching event since 1998.  Previous events happened in 1998, 2002, 2006, 2016, and 2017.  This latest bleaching has occurred even though this is a La Niña year, when more rain and cooler temperatures are supposed to help protect delicate corals.

An aerial survey of 750 separate reefs across much of the 1500 mile-long Great Barrier Reef system found severe bleaching among 60% of the corals.  The bleaching covers an area even wider than the back-to-back outbreaks in 2016 and 2017.

The bleaching is a product of a summer in Australia that started early.  December temperatures were already warmer than the historical February summer maximums.  Globally, 2021 was the hottest year on record for the world’s oceans for the sixth year in a row.

Bleached coral can recover if temperatures cool down for a long enough period, but this is becoming increasingly rare.  Between 2009 and 2019, 14% of the world’s coral reefs were lost for good.

In Australia, the plight of the Great Barrier Reef has become politicized.  The current government is not supportive of efforts to reduce the country’s fossil fuel dependence and has worked to keep the reef from being placed on the list of endangered world heritage sites.  Instead of pushing for emissions cuts, Australia has focused on a variety of long-shot projects aimed at helping the reef.

The fact is that coral reefs cannot cope with the current rate of warming and unless that slows down soon, they will simply not survive for long.

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Photo, posted September 28, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Spring is Sooner And Warmer In The United States | Earth Wise

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Despite some March snowstorms in the Northeast, the record shows that spring is getting warmer and coming sooner in the United States.

The independent research organization Climate Central analyzed 52 years of spring data across the United States.  Half of the 234 locations studied had an increase in their average spring temperatures of at least 2 degrees.  About 70% of the locations had at least 7 extra days above their normal spring temperatures.  About the only part of the country where spring hasn’t gotten much warmer is in the upper Midwest.

Over that time period, the average spring temperature in Albany, NY has increased by 2.1 degrees.  And compared with 1970, there are now 11 more warm spring days in New York’s Capital Region.

Spring warming has been greatest in the Southwest.  The three cities with the largest temperature increases were Reno, Nevada at 6.8 degrees, Las Vegas, Nevada with 6.2 degrees, and El Paso, Texas with 5.9 degrees.

Spring has been arriving early as a result of the warming conditions, cutting into the cold winter months.  While an early spring sounds like nothing but good news, the shift can cause problems.  An early spring and early last freeze can lengthen the growing season.  With it comes the arrival of mosquitoes and pollen and its associated allergy season.

A greater problem is that spring warming can disrupt the timing of ecosystem events.  For example, migratory birds could show up at the wrong time, impacting their food availability and breeding success.

As the overall climate changes, so does the spring.

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2022 Spring Package

Photo, posted March 20, 2011, courtesy of Suzie Tremmel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Historic Western Drought | Earth Wise

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The American Southwest has suffered from drought conditions since the year 2000.  The drought has reduced water supplies, devastated farmers and ranchers, and it has helped to fuel numerous wildfires across the region.  It has generally been considered to be worst in 500 years.

According to a recent analysis, the drought has become so severe that it has actually led to the driest two decades in at least 1,200 years and the changing climate is largely responsible.  The summer of 2021 was especially dry; about 2/3 of the West was in severe drought conditions.

Scientists at UCLA used tree ring data to gauge drought.  Based on that analysis, 2000-2021 is the driest 22-year period since 800 A.D. which is as far back as the data goes.

The study confirmed the role of temperature, more than precipitation, in driving exceptional droughts.  Precipitation levels can go up and down over time and can vary in different regions.  But the ongoing emissions of greenhouse gases into the atmosphere are causing temperatures to generally rise over time.  Warmer temperatures make the air more capable of pulling water out of the soil, out of vegetation, out of crops, and out of forests.  All of that makes drought conditions more severe.

A megadrought is generally considered to be one that is both severe and long.  But even during one, there can be wet years.  2005 was a notable one.  But there must be enough consecutive wet years to actually end a drought.

Several previous megadroughts over the past 1,200 years lasted as long as 30 years.  So, the current drought is in full swing and may go on for a long time to come.

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How Bad Is the Western Drought? Worst in 12 Centuries, Study Finds.

Photo, posted September 25, 2021, courtesy of David Sierralupe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Beavers Are Flooding The Warming Arctic | Earth Wise

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The accelerating warming in the Arctic has transformed the region into a warmer, wetter, and more diverse environment.  Warming temperatures have encouraged the increasing growth of vegetation, particularly shrubs that provide beavers with bark to eat and branches to build with.  Warming temperatures also mean that lakes and streams freeze solid for shorter periods of time or not at all, allowing beavers to pursue their construction projects for longer periods during the year.

Prior to the mid-1970s, residents of the Alaskan Arctic encountered few beaver ponds.  In 2018, researchers using satellite imagery mapped 12,000 beaver ponds in Alaskan tundra.

Beavers are causing major changes in the streams and floodplains that many small Alaskan villages depend upon for food, water, and navigation.  As the rodents transform lowland tundra ecosystems, they are eliminating food sources, deteriorating water quality, and making it difficult to navigate waterways.

The migration of beavers across the Arctic landscape is largely a result of climate change.  But it is also becoming one of the factors amplifying climate change.  Scientists are trying to figure out the degree of permafrost thawing that beaver dam-and-den building is causing and how fast these defrosted organic soils will degrade and release trapped carbon and methane.

Beaver dams alter the hydrology of streams by slowing the flow, storing and spreading water to create wetlands, raising the water table, and lowering the oxygen content of the water. 

Climate-driven changes in species distributions affect human well-being as entire ecosystems continue to change.  Shifts in animal habitat stimulated by climate change could have profound consequences across the globe.

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Beavers Are Flooding the Warming Alaskan Arctic, Threatening Fish, Water and Indigenous Traditions

Photo, posted June 12, 2018, courtesy of Peter Pearsall/USFWS 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.

The Pacific Northwest Heatwave | Earth Wise

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The late-June heatwave in the Pacific Northwest shattered temperature records in dozens of locations.  Cities like Portland and Seattle saw historic high temperatures and one town in British Columbia saw temperatures hotter than ever recorded in Las Vegas.

An international team of weather and climate experts analyzed this extreme weather event and came to a preliminary conclusion that it was a 1-in-1000-year event in today’s climate.  “Today’s climate” means the already warmer conditions that the world is experiencing as a result of the changing climate.

If that analysis is accurate, then such an extreme temperature event would have been at least 150 times rarer in the era before global warming.  In other words, they concluded that it would have been a 1-in-150,000-year event, which means that it would have been virtually impossible in pre-industrial times.

Given that they estimated that the extreme temperatures were a 1-in-1000-year event at this point, it would follow that such events are not about to become commonplace any time soon.  On the face of it, that is somewhat comforting to hear.

However, all of this assumes that global warming will not radically change the statistical distribution of global temperatures.  If that assumption fails to hold, then all bets are off.  Perhaps temperatures like those experienced in the Pacific Northwest might be a 1-in-50-year event, for example, but we just don’t realize it yet.  Follow-up studies will be looking for evidence of significant changes in the distribution of weather events.  For now, a 1-in-1000-year event means there is only a 0.1% chance of occurring in a given year.  That’s good news for the residents of that region.

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Preliminary analysis concludes Pacific Northwest heat wave was a 1,000-year event…hopefully

Photo, posted June 4, 2016, courtesy of Jody Claborn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Greenland Becoming Darker | Earth Wise

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According to research published by Dartmouth University, a weather pattern that pushes snowfall away from parts of Greenland’s ice sheet is causing the continent to become darker and warmer.

Reducing the amount of fresh, lighter-colored snow exposes older, darker snow on the surface of Greenland’s ice sheets.  Fresh snow is the brightest and whitest. The reflectivity of snow decreases fairly quickly as it ages. This decrease in albedo – or reflectivity – allows the ice sheet to absorb more heat and therefore melt more quickly. 

The research attributes the decrease in snowfall in Greenland to a phenomenon called atmospheric blocking in which persistent high-pressure systems hover over the ice sheet for up to weeks at a time.  Such systems have increased over Greenland since the mid-1990s.  They push snowstorms to the north, hold warmer air over Western Greenland, and reduce light-blocking cloud cover.

All of this contributes to Greenland melting faster and faster.  According to research cited in the study, the Greenland ice sheet has warmed by nearly 5 degrees Fahrenheit since 1982.  Overall, Greenland is experiencing the greatest melt and runoff rates in the last 450 years, at the minimum, and quite likely the greatest rates in the last 7,000 years.

The Greenland ice sheet is the second largest ice body in the world, after the Antarctic ice sheet.  It is 1,800 miles long and about 700 miles wide at its greatest width.  Its thickness is between 1.2 and 1.9 miles.  If the entire sheet were to melt, it would lead to a global sea level rise of 24 feet.  So, the darkening of Greenland is a source of great concern.

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Greenland Becoming Darker, Warmer as Snow Changes

Photo, posted April 3, 2012, courtesy of Francesco Paroni Sterbini via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Mega-Droughts | Earth Wise

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According to a new report led by researchers from the University of Queensland in Australia, mega-droughts are expected to increase as global temperatures rise with the progression of climate change.  While mega-droughts have no strict scientific definition, most studies – including this one – define them as prolonged droughts lasting two decades or longer. 

The research team analyzed geological records from the Eemian Period – 129,000 to 116,000 years ago – to create a model of what to expect over the next 20-50 years.  The Eemian Period is the most recent in Earth’s history when global temperatures were similar – or maybe even slightly warmer – than they are today. 

By analyzing the climate during this period, the research team found that the world will likely experience increased water scarcity, reduced winter snow cover, more frequent wildfires and wind erosion as a result of global warming.

In the report, which was recently issued by the University of Queensland, the researchers collaborated with the New South Wales Parks and Wildlife Service to identify stalagmites in the northern section of Kosciuszko National Park.  They were able to study small samples of calcium carbonate powder contained in the cave stalagmites, allowing them to identify periods of reduced precipitation during the Eemian Period. 

Historically, mega-droughts have been associated with mass exoduses of people from the affected areas.  In fact, mega-droughts are suspected of contributing to the collapse of several pre-industrial civilizations across Southeast Asia and the Americas.

If humans continue to warm the planet, the researchers say more mega-droughts will be in our future.

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Expect more mega-droughts

Photo, posted March 28, 2014, courtesy of Marufish via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Alaska Is Getting Wetter | Earth Wise

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Siberia has been in the news for record-setting heat waves and wildfires, but it is not the only northern region experiencing unusual weather.   Alaska, apart from setting its own warm weather records, is experiencing the rainiest five years in its century-long meteorological record.

Extreme weather in the Arctic is being driven by an aspect of climate change called Arctic amplification, which leads to temperatures rising faster than the global average.  The physical basis of Arctic amplification is well understood, but its effects over time are much less predictable.

The past five years included two summers with average precipitation, one that was a little drier than usual, and two of the wettest summers on record.    Researchers have taken measurements of how far below the surface permafrost has thawed by the end of summer over a wide range of Alaskan environments.

About 85% of Alaska sits upon permafrost and the increasing rainfall over the past five years is leading to a deeper thaw of permafrost across the state.  The wettest summer on record was 2014 and permafrost didn’t freeze back to previous levels even when the next couple of summers were relatively drier.

The study demonstrated how different types of land cover govern relationships between summer rainfall and permafrost thaw.  As Alaska becomes warmer and wetter, the vegetation cover is projected to change, and the increasing occurrence of wildfires will disturb larger areas of the landscape.  These conditions are likely to lead to a feedback loop driving more and more permafrost thawing.

Fundamental changes to Alaskan ecosystems are occurring on an unprecedented timescale – not gradually over decades or lifetimes, but over mere months or years.

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Alaska is getting wetter. That’s bad news for permafrost and the climate.

Photo, posted June 10, 2011, courtesy of Peter Rintels via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Cooling The Earth With A Warmer Arctic | Climate Change | Earth Wise

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Researchers are considering a wide range of approaches to mitigate the effects of global climate change.  Among these are various strategies of geoengineering, which must be viewed with enormous caution, given the high likelihood of unintended consequences from almost anything we might do.

Researchers at the International Institute for Applied Systems Analysis have investigated potential strategies for cooling the planet in the absence of Arctic sea ice.

The Arctic region is heating up faster than any other place on earth and its sea ice is rapidly disappearing.  Estimates are that summer sea ice in the Arctic Ocean will be largely gone within a generation.  Arctic ice and snow reflect the sun’s energy into space, which helps to keep the planet cool.  What happens if that ice is gone?

The researchers explored the fact that the Arctic Ocean ice actually insulates the Arctic atmosphere from the warmer water under the ice.  Without the ice layer, the surface water would actually increase air temperatures by 20 degrees C during the winter.  That in turn would increase the heat irradiated into space and thereby cool down the planet.

The Arctic sea ice is in part maintained because the upper regions of the Arctic Ocean have lower salinity than the Atlantic Ocean.  This stops Atlantic water from flowing above the cold Arctic waters.  So, if we were to somehow deliberately increase the salinity of the Arctic Ocean surface water, warmer, less salty Atlantic Ocean water would flow in, increase the temperature of the Arctic atmosphere, and release heat trapped in the ocean into space.

It all sounds pretty crazy, but the researchers say that given the seriousness of climate change, all options should be considered when dealing with it.

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Could we cool the Earth with an ice-free Arctic?

Photo, posted August 19, 2016, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And El Niño

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The term El Niño refers to a large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperature across the central and east-central equatorial Pacific Ocean.  Amazingly, the phenomenon was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean.

According to a new study published in the Proceedings of the National Academy of Sciences, climate change is increasing the frequency of extreme El Niño events, leading to intensifying droughts, worsening floods, and shifting hurricane patterns.

The study, led by scientists in China and the US, looked at data from 33 El Niños dating back to 1901.  Since the 1970s, El Niños have been forming farther to the west in the Pacific Ocean, where temperatures are warmer.  Strong El Niños can cause severe drought in dry climates such as Australia and India, intense flooding in wetter climates such as the US Pacific Northwest and Peru, and more hurricanes to form in the Pacific and fewer in the Atlantic.

Before 1978, 12 out of 14 El Niños formed east of the International Dateline.  Since 1978, all 11 have formed in the central or western Pacific Ocean a shift of hundreds of miles.  There have been three so-called super El Niños since the shift – in 1982, 1997, and 2015.  These have set new average temperature records and triggered catastrophic natural disasters.

With rising global temperatures, El Niños are likely to continue to intensify, with major impacts on human societies around the world.

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Climate Change is Making El Niños More Intense, Study Finds

Photo, posted January 20, 2016, courtesy of Los Angeles District via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Cooling Down Urban Heat Islands

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Researchers have known about and studied the urban heat island effect for quite some time.  Since large cities began to emerge in the 19th century, it has been understood that various aspects of the urban environment lead to warmer temperatures than the surrounding countryside.

Researchers led by a group at Portland State University in Oregon have been utilizing a new way of studying the urban heat island effect.  They have used citizen science volunteers in 24 cities around the world to map temperatures in the cities at ground level in great detail using mobile sensors attached to slow-moving vehicles.  Previous studies have used data from satellite or stationary sensors.  They have learned that the urban heat island effect is more complicated, more varied, and subtler than the earlier data indicated.

They found that there are six things that affect urban heat. Three are living — the volume of the tree canopy, the height of the tree canopy, and the ground level vegetation. Three are human-built — the volume of buildings, the difference in building heights, and the coloring of the buildings.

Buildings can have both negative and positive effects. Tall buildings that cast shade actually lower relative afternoon temperatures, while densely packed shorter buildings, like the big-box stores in suburban areas, lead to hotter afternoon temperatures. The studies show that increasing the difference in building heights in an area creates more air circulation, which has a cooling effect.

The study also showed that urban heat is a social justice issue.  Lower-income neighborhoods largely barren of trees have considerably higher temperatures than more affluent, tree-shaded areas.

Such detailed research can be used to guide decisions in urban planning with regard to trees, building heights, and the color and type of surfaces in our urban spaces.

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Can We Turn Down the Temperature on Urban Heat Islands?

Photo, posted July 21, 2009, courtesy of Daniel Dionne via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change Is Not Natural

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It has been the overwhelming consensus of the scientific community for a long time that human activity and other external factors are responsible for the continuing rise in global temperature.  Despite this widespread agreement, there have been those who argue that natural ocean cycles might be influencing global warming over the course of multiple decades.

A new study, published in the Journal of Climate, provides an answer to the question of how much influence natural cycles might have, and that answer is very little to none.

The study looked at observed ocean and land temperature data since 1850 and, apart from human-induced factors such as greenhouse gas concentrations, took into account other occurrences such as volcanic eruptions, solar activity, and air pollution peaks.  The findings demonstrated that slow-acting ocean cycles do not explain the long-term changes in global temperatures.

Based on the study, the researchers can state with confidence that human factors like greenhouse gas emissions and particulate pollution, along with year-to-year changes caused by natural phenomena like volcanic eruptions or El Niño, are sufficient to explain virtually all the long-term changes in temperature.  The idea that the oceans could have been driving the climate either in a colder or warmer direction for multiple decades in the past and therefore will do so in the future is unlikely to be correct.

A number of previous studies have compared flawed observations with flawed modeling results to claim that naturally-occurring ocean cycles have played a large role in global temperatures.  The new study shows that such cycles have little influence on the climate.  Reducing greenhouse gas emissions is really what we need to do.

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Global temperature change attributable to external factors, confirms new study

Photo, posted November 13, 2007, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Dolphins

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We don’t think of heatwaves as something that affects the ocean, but increasingly, as the planet warms, there have been instances where ocean water temperatures become much higher than normal for extended periods of time.  There has been much discussion of this phenomenon with regard to coral reefs where the catastrophic rise in coral bleaching events has been the result.

Recently, a study at the University of Zurich looked at the effects of ocean heatwaves on marine life higher in the food chain.  They studied the well-known dolphin population in Shark Bay, Western Australia.

In early 2011, a heatwave caused water temperatures in Shark Bay to rise more than 4 degrees above the annual average for an extended period.  This led to a substantial loss of seagrass, which is a driving factor in the Shark Bay ecosystem.

The researchers investigated how this environmental damage affected survival and reproduction of dolphins, using long-term data on hundreds of animals collected over a ten-year period from 2007 to 2017.

Their analysis showed that dolphins’ survival rate dropped by 12% and female dolphins were giving birth to fewer calves.  That phenomenon that began in 2011 lasted at least until 2017.

The researchers were surprised by the extent and the duration of the influence of the heatwave, especially the fact that the reproductive rate of dolphins had not returned to normal even after 6 years.

This study shows for the first time that marine heatwaves not only affect organisms at the lower levels of the food chain, but also might have considerable long-term consequences for the animals at the top, such as dolphins.

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Climate change is a threat to dolphins’ survival

Photo, posted December 14, 2014, courtesy of Ed Dunens via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Forecasting A Bad Year For Carbon

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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.

WAMC Northeast Public Radio

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