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Rainforests and thunderstorms

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Tropical forests are dying at an alarming rate, and not just from deforestation. Even intact forests are losing trees, threatening biodiversity, carbon storage, and the global climate. While drought and rising temperatures are often blamed, new research points to a surprising culprit: thunderstorms.

These intense, short-lived convective storms, common in the tropics, are increasing due to climate change. With strong winds and lightning, they can snap trees, strip canopies, and kill even the most robust tree specimens.

In a perspective paper recently published in the journal Ecology Letters, a research team led by the Cary Institute of Ecosystem Studies argues that thunderstorms, often overlooked in carbon storage research, may be the leading cause of tree death in tropical forests. The research team estimates that storms have caused 30 to 60% of tree mortality in the past, a number that is likely rising as storm activity increases 5 to 25% each decade.

Including storm data in forest carbon studies changes the picture significantly. Earlier models showed that carbon levels dropped sharply when temperatures rose beyond a certain point. But when storm impacts were added, that pattern disappeared, suggesting that storms – not just heat – may be a key factor in carbon loss.

Understanding which species are most vulnerable is critical for reforestation and conservation efforts. Mature trees store the most carbon, so if they’re lost to storms, future forests may fall short of their carbon storage potential.

As storm activity increases each decade, the stakes grow higher.  Accounting for storms could reshape how we protect, restore, and plan for the future of our forests. 

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Are the Amazon’s biggest trees dying? Forest coroners investigate

Photo, posted July 2, 2017, courtesy of Anna & Michal 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

National drought

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Climate change brings with it many kinds of extreme weather.  It isn’t just higher temperatures.  It is changing patterns of weather and weather events that are rare or even unprecedented.

Late October saw drought conditions throughout almost the entire United States.   Only Alaska and Kentucky did not have at least moderate drought conditions.

The previous four months were consistently warmer than normal over a large area of the country.  When that period started, about a quarter of the country was at least somewhat dry, but in late October, 87% of the country was dry.

Droughts in many parts of the U.S. and in places around the world are becoming more frequent, longer in duration, and more severe. 

Residents of New York City were urged to start conserving water.  This October was the driest October since record keeping began in 1869.  The upstate reservoirs that supply New York’s water were below two-thirds full.  They are normally more than three-quarters full in the fall.

Even the Southeast, which received huge amounts of rain from Hurricane Helene, is experiencing drought.  Not much rain had fallen since that storm and warmer temperatures mean more evaporation and drier soils.

Drought is not just a lack of precipitation.  Drought conditions are driven by abnormally high temperatures that remove moisture from the atmosphere and the ground.

Whether widespread drought conditions will persist is unknown.  If a predicted La Niña condition develops in the tropical Pacific, drought conditions in the southern half of the country could get worse, but the Northeast could see lots of rain and snow.

To have nearly the entire country experiencing drought conditions is pretty rare.  But unusual weather is becoming the new normal.

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In a Record, All but Two U.S. States Are in Drought

Photo, posted May 21, 2024, courtesy of Adam Bartlett via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

South American drought

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Vast areas of South America have been gripped in drought conditions for months.  Rivers in the Amazon basin fell to record-low levels in October.  The drought has amplified wildfires, parched crops, disrupted transportation networks, and interrupted hydroelectric power generation in parts of Brazil, Bolivia, Colombia, Ecuador, Peru, and Venezuela.

The drought is related to the impact of the El Niño that was present for the latter part of 2023 and the first half of this year.  El Niño typically shifts rainfall patterns in such a way that there is reduced rainfall in the Amazon.  This is especially true during the dry season months of July, August, and September.

Forecasts earlier in the year warned that there would be extreme fire conditions during the dry season.  Indeed, the Pantanal region that spans parts of southern Brazil, Paraguay, and Bolivia has experienced one of its worst fire seasons in decades.  The lack of rainfall, low soil moisture, and drawdowns of groundwater helped to amplify fires and caused them to spread faster and farther.

The drought has strained power supplies in Brazil and Ecuador because hydroelectric power stations are producing less electricity.   Snarled transportation networks with impassible rivers have left some communities struggling to get supplies. 

Brazil’s National Center for Monitoring and Early Warning of Natural Disasters has called the current drought the most intense and widespread Brazil has ever experienced.  Late October saw 293 Brazilian municipalities facing extreme drought.

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Intense, Widespread Drought Grips South America

Photo, posted August 13, 2010, courtesy of Colm Britton via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Sounds Of Coral Reefs | Earth Wise          

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Coral reefs around the world face multiple threats from climate change, pollution, and other impacts of human activity.  Reef conservation and restoration projects must be able to monitor the health of reefs and that is not such a simple matter.  Surveying reefs generally is labor-intensive and time consuming.  But in a new study, scientists at the University of Exeter in the UK have found a new way to do it.

The fish and other creatures living on coral reefs produce a vast range of sounds.  The meaning of these various sounds is for the most part unknown, but reefs nonetheless have distinctive sonic signatures.

The Exeter researchers decided to make use of machine learning technology.  They trained a computer algorithm using multiple recordings of both healthy and degraded coral reefs.  This essentially taught the computer to learn the difference between them.  A computer can pick up patterns that are undetectable to the human year.  This application of artificial intelligence can tell us faster and more accurately how a reef is doing.

The computer was then used to analyze a set of new recordings, and successfully identified reef health 92% of the time.  The team then was able to use this technique to track the progress of reef restoration efforts.

It is generally much cheaper and easier to deploy an underwater hydrophone on a reef and leave it there instead of having expert divers make repeated visits to a reef to survey its status.  Sound recorders and artificial intelligence could be used around the world to monitor the health of coral reefs and determine whether efforts to protect and restore them are working.

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AI learns coral reef “song”

Photo, posted January 11, 2015, courtesy of Falco Ermert via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Declining Bird Populations | Earth Wise

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A study by scientists from multiple institutions around the world including Cornell University has found that significant declines in bird populations are taking place across the planet.  Loss and degradation of natural habitats, direct overexploitation of many species, and climate change are driving the bird population declines.

According to the study, approximately 48% of existing bird species worldwide are known or suspected to be undergoing population declines.  The populations of 39% of bird species appear to be stable.  Only 6% of birds have increasing populations.

A study in 2019 determined that nearly 3 billion breeding birds have been lost in the U.S. and Canada over the past 50 years.  The new study shows that the same patterns of population decline and extinction are happening globally.  According to the study, there are now the first signs of a new wave of extinctions of continentally distributed bird species.

The ultimate fate of bird populations is strongly dependent on stopping the loss and degradation of habitats.   Habitat loss is generally driven by human demand for resources.  Reducing the human footprint on the natural world is what is needed.  Birds are a highly visible indicator of environmental health, and their declining populations signal a much wide loss of biodiversity and threats to human health and wellbeing.

There is a global network of bird conservation organizations trying to prevent further loss of bird species and bird abundance.  Keeping track of the situation is essential and there is growing participation by the public in bird monitoring.  But ultimately, it depends on governments and society in general to support sustainable resource use and learn how to share the planet with nature.

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Global Bird Populations Steadily Declining

Photo, posted January 9, 2022, courtesy of Martien Brand via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Dam Failures Likely | Earth Wise

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Two dams in Central Michigan were breached by rain-swollen floodwaters in May and forced the evacuation of tens of thousands of residents and prompted officials to warn of life-threatening danger from a flooded chemical complex and a toxic waste cleanup site.  Engineers say that most dams in the U.S. were designed many decades ago – in some cases, a century ago – and are not suited to a warming world with ever stronger storms.

The dams in Michigan gave way for the same reason behind most dam failures:  they were overwhelmed by water, in this case by five inches of rain falling over two days after earlier storms had saturated the ground and swollen rivers.

It can’t be proven whether this specific set of events was triggered by climate change, but global warming is definitely causing some regions to become wetter and is increasing the frequency of extreme storms.  And these trends are expected to continue as the world continues to warm.

All of this puts more of the 91,500 dams in the U.S. at greater risk of failing.  The American Society of Civil Engineers, in its latest report card on infrastructure issued in 2017, gave the nation’s dams a “D” grade.

Historically, dams have been designed based on past weather history to predict the magnitude of the maximum potential flood that a dam would have to withstand.  There was no expectation that future weather patterns might be very different.  Infrastructure designers will clearly need to change their practices.

For existing dams, operational changes might be called for, such as reducing water levels in anticipation of more extreme storms.  Upgrades might include changing spillway designs to accommodate larger water volumes over a longer time period.

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‘Expect More’: Climate Change Raises Risk of Dam Failures

Photo courtesy of Eye in the Sky/Youtube.

Earth Wise is a production of WAMC Northeast Public Radio.

Bird Migration And Climate Change | Earth Wise

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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.

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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.

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.

100% Renewables Does Not Necessarily Mean Carbon-Free

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Hundreds of companies around the world have committed to use 100% renewable energy in order to fight climate change.  But a new study from Stanford University points out that 100% renewable energy does not necessarily mean 100% carbon-free energy.

The problem is that the carbon content of electricity can vary a lot over the course of a day in many locations.  Using yearly averages can overstate the carbon reductions associated with a particular power source, in some cases by significant amounts.

Suppose a California company purchases or generates enough solar power to match 100% or more of their electricity use over the course of the year.  In reality, it may generate far more electricity than it uses during the afternoon and sell the excess.  Then, at nighttime, it purchases power from the grid, which would be far more carbon-intensive if it involves the burning of fossil fuels.

But in Britain, for example, the situation is very different.  With a high reliance on wind power, grid carbon intensity is actually lower at night.  So very different consumption patterns over the course of a day would be less carbon-intensive.

If sufficient energy storage capacity can be implemented into the grid as well as suitable long-range transmission, these time-based fluctuations in the electricity supply could be ironed out.  Until such time, electricity consumers need to evaluate the environmental benefits of their renewable strategies on an hourly basis rather than using averages.  And the best strategies are entirely dependent upon the characteristics of the specific grid they interact with.  The need for this kind of analysis will only grow as renewable generation expands.  Transparent, precise and meaningful carbon accounting is necessary.

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100% renewables doesn’t equal zero-carbon energy, and the difference is growing

Photo, posted January 29, 2013, courtesy of U.S. Fish and Wildlife Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Insurance

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While there are still some people who remain dubious about the reality of climate change, insurance companies are not among them.  And, in fact, insurers are warning that climate change could make coverage for ordinary people unaffordable.

Munich Reinsurance, the world’s largest reinsurance firm, blamed global warming for $24 billion in losses from California’s recent wildfires.  Such costs could soon be widely felt as premium rises are already under discussion with insurance companies having clients in vulnerable parts of the state.

With the risk from wildfires, flooding, storms and hail increasing, the only sustainable option for the insurance industry is to adjust risk prices accordingly.  Ultimately, this may become a social issue.  Affordability of insurance is critical because if rates go up too much, many people on low and average incomes in some regions may no longer be able to buy insurance.

The great majority of California’s 20 worst forest fires since the 1930’s has occurred since the year 2000 driven by abnormally high summer temperatures and persistent drought. The reinsurance giant analyzed decades of data with climate models and concluded that the fires are likely driven by climate change.

It isn’t just wildfires.  Insurance premiums are also being adjusted in regions facing an increased threat from severe convective storms whose energy and severity are driven by global warming.  These include parts of Germany, Austria, France, southwest Italy, and the U.S. Midwest.

Linking extreme weather events to climate change is a bit like attributing the performance of a steroid-using athlete to drug use.  The connections are clearer in patterns than in individual disasters.  But the pattern these days is pretty clear.

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Climate Change Could Make Insurance Unaffordable for Most People

Photo, posted June 12, 2013, courtesy of Jeff Head via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shipping And Invasive Species

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The increasing numbers of invasive species around the world are a major driver of biodiversity change and cause billions of dollars in economic damages annually.  Climate change is a major factor in the spread of invasive species, but a new study by McGill University suggests that global shipping growth will far outweigh climate change in the spread of non-indigenous pests to new environments in the coming decades.

One of the most significant ways in which the disparate regions of the world are interconnected is via transportation networks.   The global shipping network is the primary means by which materials and goods are moved worldwide, accounting for over 80% of world trade.  And for this reason, the global shipping network is responsible for much of the introduction of non-indigenous species across the planet.

Living organisms are often transported through ballast water, which is taken up to stabilize cargo vessels.  Other species are transported by biofouling, whereby they attach to the hulls of ships.  Taken together, these two pathways account for anywhere between 60 and 90% of marine bioinvasions.   (Terrestrial invaders are generally moved as a byproduct of shipping, for example by infesting wood packaging material).

The McGill study looked at trends in global shipping and how socioeconomic factors are driving change.  For example, China’s share of global container throughput has gone from 1.4% in 1990 to 20.1% in 2013.  So, the distribution and patterns of shipping have been changing dramatically and with it the spread of non-indigenous species.

Awareness of this issue is increasing.  For example, there have been policy initiatives such as the International Ballast Water Management Convention that is an effort to control bio-invasions through measures such as ballast exchange.  We need to take measures to limit the unintentional spread of species.

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Global forecasts of shipping traffic and biological invasions to 2050

Photo, posted December 3, 2009, courtesy of Roger W via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dietary Diversity And Health

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For decades, we have heard from public health sources that we should eat a variety of foods.  Dietary diversity is touted as important for health.  However, there has never really been a consensus about what so-called dietary diversity actually  is, how it is measured, or how it necessarily is healthy.

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Traffic Jams In The Jet Stream

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Many extreme weather events are associated with unusual behavior by the jet stream.   Jet streams are the global air currents that circle the earth.  The meandering and speed changes in the jet stream affect weather and also play a big role in how long it takes aircraft to make their way across the country.  The behavior that leads to extreme weather events is known as “blocking” in which the meandering jet stream stops weather systems from moving eastward.

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Extreme Weather Increasing

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It sure seems like extreme weather is increasingly common:  floods, droughts, extreme rainfall, powerful snowstorms, hurricanes and so on.  But we tend to focus on recent events and often give them undue emphasis.  So, it is reasonable to ask whether extreme weather really is more common these days.

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Mapping Emerging Infectious Diseases

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Ebola. Hantavirus. Lyme disease. What do they have in common? Like most emerging infectious diseases, they originated in mammals. So many debilitating pathogens make the jump from wildlife and livestock to humans, yet at the global scale little is known about where people are most at risk of outbreaks.

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