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Thoreau And Climate Change

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Henry David Thoreau was a 19th-century American naturalist, philosopher, poet, essayist, and social reformer.  He is best known for “Civil Disobedience,” an essay advocating for the rebellion against an unjust government, and for “Walden,” a book about his experiences living simply in nature.  Now, Thoreau’s observations from “Walden” are the foundation of a new study exploring the effects of climate change on tree leaf-out and the emergence of spring wildflowers. 

This research, which was recently published in the journal Ecology Letters, relies on Thoreau’s scientific observations gathered during the 1850s when he spent 26 months living in isolation at Walden Pond in Concord, Massachusetts.  These observations from Thoreau were combined with current research to measure tree and wildflower leaf-out dates for 37 different years between 1852 and 2018.  “Leaf out” refers to the time in spring when plants and trees begin producing leaves.  An alteration in this timing can have a domino effect throughout an ecosystem.

Over the past century, temperatures in Concord, Massachusetts have warmed five degrees Fahrenheit.  As a result, leaf-out dates have changed significantly.  According to researchers, wildflowers are leafing out about one week earlier, while trees are leafing out about two weeks earlier than they did 160 years ago. 

Ground-dwelling plants like wildflowers have a narrow window to accomplish growth, photosynthesis, and reproduction, before the canopy trees leaf out and block the sunlight.  Temperature-driven shifts in the timing of tree leaf-out between Thoreau’s time and now are likely already hindering wildflower abundance and flowering. 

As the climate continues to warm, the already small window of time between wildflower emergence and tree leaf-out will likely shorten further. 

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Using Thoreau, scientists measure the impact of climate change on wildflowers

Photo, posted August 13, 2008, courtesy of Adam Pieniazek via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Way To Make Solar Cells

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Millions of rooftops now contain solar panels and the majority of the solar cells that make up those panels today are made from silicon.  Silicon solar cells require expensive, multi-step processing conducted at very high temperatures in special clean room facilities.  Despite these complications, the price of solar panels has continued to drop dramatically over the years.

But even as the price of solar cells gets lower and lower, there are still widespread efforts to find even better ways to make them.   One of those ways is with perovskite solar cells.  Perovskites are materials with a characteristic crystal structure and are quite common in nature.  Perovskites can be formed with a wide range of elements and can exhibit a variety of properties.

They were first used to make solar cells about 10 years ago and those first cells were unimpressive in most respects.  However, there has been steady progress since that time.  The potential advantages of perovskite solar cells are that they can be made from low-cost materials and can be manufactured using liquid chemistry, a far cheaper process than what is used to make silicon cells.

Researchers at MIT and several other institutions have recently published the results of research on how to tailor the composition of perovskite solar cells to optimize their properties.   What used to be a trial-and-error process can now become much more engineered and should lead to perovskite solar cells with performance that could exceed that of silicon cells.

Silicon solar panels are a huge, worldwide industry and displacing them in favor of an alternative technology is a tall order.  But if perovskite cells can be optimized for large-scale manufacturability, efficiency and durability, they could definitely give silicon a run for its money.

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Unleashing perovskites’ potential for solar cells

Photo courtesy of Ken Richardson/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

Melting Ice In Greenland

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The Greenland ice sheet is the second largest ice body in the world after the Antarctic ice sheet.  It covers over 660,000 square miles, more than twice the size of the state of Texas.  But it is melting.

According to a new study published in the journal Nature, the Greenland ice sheet is melting faster today than at any point in the last 350 years.  A team of U.S. and European researchers analyzed more than three centuries of melt patterns in ice cores from western Greenland. They then linked this historical data to modern observations of melting and runoff across the entire ice sheet.

According to the researchers, from an historical perspective, today’smelt rates are off the charts.  There is a 50% increase in total ice sheet melt water runoff since the start of the industrial era and a 30% increase since the 20th century alone.

Over the last 20 years, melt intensity has increased 250 to 575 percent compared to pre-industrial melt rates. The period from 2004-2013, the most recent decade analyzed, experienced a more sustained and greater magnitude of melt than in any previous 10-year period in the 350-year record.

The Greenland ice sheet is the largest single contributor to global sea level rise.  It is adding 72 cubic miles of meltwater to the world’s oceans every year.

The melting of the Greenland ice sheet is accelerating which is a frightening prospect.  If the sheet were to melt in its entirety, global sea levels would rise by 23 feet.  The world needs to do whatever it can to keep that doomsday scenario from happening.

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Greenland Ice Sheet Melting At Fastest Rate in 350 Years

Photo, posted September 8, 2014, courtesy of Marco Verch via Flickr.  

Earth Wise is a production of WAMC Northeast Public Radio.

Examining Sea Level Rise

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It’s no secret that sea levels along the East Coast of the United States are rising.  But what’s less known is that the water isn’t rising at the same rate everywhere.  As the climate continues to change, some cities may remain dry while others struggle to keep water out. 

During the 20th century, sea levels rose about 18 inches near Cape Hatteras in North Carolina and along the Chesapeake Bay in Virginia.  During that same time period, New York City and Miami experienced a 12 inch sea level rise, while the waters near Portland, Maine only rose 6 inches.  According to a study recently published in the journal Nature, there’s an explanation for this. 

The variation is a result of a phenomenon called “post-glacial rebound.”  During the last ice age, huge sheets of ice once covered land areas in the Northern Hemisphere, including parts of the Northeast U.S.  The weight of the ice weighted down the land like a boulder on a trampoline.  At the same time, peripheral lands such as the U.S. mid-Atlantic coast rose up.  As the ice melted, the previously weighted-down regions rebounded while the peripheral lands began to sink.  While these ice sheets disappeared some 7,000 years ago, this see-sawing of post-glacial rebound continues to this day. 

Researchers combined data from GPS satellites, tide gauges, and fossils in sediment with complex geophysical models to produce this comprehensive view of sea level change since 1900.  While post-glacial rebound accounts for most of the sea level variation along the East Coast, researchers noted that when that factor is stripped away, “sea level trends increased steadily from Maine all the way down to Florida.”

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Why is sea level rising faster in some places along the US East Coast than others?

Photo, posted August 24, 2014, courtesy of Bill Dickinson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Is There Hope For Coral Reefs?

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News about the world’s coral reefs has been relentlessly bad for a number of years.  Warming, acidifying oceans have wreaked havoc with coral reefs leading to enormous losses.  Nowhere have things been more dire than in Australia’s Great Barrier Reef.  Coral bleaching events have been increasingly common and severe over the past two decades.  In fact, only 7% of the Great Barrier Reef has escaped bleaching entirely since 1998.

While the future of the world’s coral reefs is very much uncertain as global heating continues, there is a recent bit of hopeful news.   According to a study published in Nature Climate Change, the response of the Great Barrier Reef to the extreme temperatures in 2017 was quite different from that of the previous year in the aftermath of back-to-back bouts of coral bleaching.

Surprisingly, corals that bleached in 2016 but managed to survive were more resistant to the recurrence of hot conditions in 2017.

Many corals don’t survive bleaching events at all and, of course,those corals don’t bleach for a second time. But the surviving corals from the 2016 bleaching event were tougher species.   As a result of bleaching, the mix of coral species on the reef is changing very rapidly.  The net result was that there was less bleaching in 2017 even though the temperatures that year were even more extreme than in 2016.

There have now been four mass bleaching events on the Great Barrier Reef over the past 20 years and it is only a matter of time before another one occurs triggered by the next marine heatwave. Almost half of the corals on the northern two-thirds of the reef have been killed.  But at least some of the reef is showing impressive survival skills.

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A glimmer of hope for the world’s coral reefs

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

Earth Wise is a production of WAMC Northeast Public Radio.

Increasing Antarctic Ice Loss

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Antarctica’s ice sheets contain enough frozen water to raise sea levels globally about 190 feet.  Ice in the Antarctic is melting at a record-breaking rate and subsequent sea rises could have catastrophic consequences around the world.  So, it is no surprise that scientists have been closely tracking ice loss in recent decades to understand both the current and future impacts of climate change.

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Conflicts In Conservation

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In recent years there has been a great deal of discussion about animal intelligence and the idea of animal consciousness.   In the past, the notion that animals have feelings had been relegated to fringe status, but these days, a wealth of scientific findings has made it much more mainstream to entertain such ideas.

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Hurricanes Are Slowing Down

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According to a new study recently published in the scientific journal Nature, some hurricanes are moving slower and spending more time over land, which is leading to catastrophic rainfall and flooding. The speed at which hurricanes track along their paths – known as translational speed – can play a major role in a storm’s damage and devastation.  17

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The Restoration Economy

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Deforestation is one of the largest contributors to climate change.  Forests cover about 30% of the world’s land area and are a crucial sink for carbon dioxide.   Over time, we have been steadily reducing the amount of forest in the world to obtain wood and timber, open up farmland, build towns and cities, produce paper, make palm oil, and mine for minerals.

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Reviled Animals Can Be Beneficial

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Predators and scavengers are widely persecuted by people because they are often harmful to property, livestock, and human beings.  Nonetheless, research has shown that many of these animals play important roles in ecosystems and their removal can be quite harmful.

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Biomimicry Is Big

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Biomimicry is learning from and then emulating nature’s forms, processes, and ecosystems to create more sustainable designs.   Mother Nature is already the inspiration for countless products and designs ranging from Velcro copied from plant burs to the shape of wind turbines modeled after whale fins.  There are wetsuits inspired by beaver pelts and office buildings that copy termite dens.  Increasingly, innovators are looking at nature for designs in architecture, chemistry, agriculture, energy, health, transportation, computing, and even for the structure of organizations and cities.

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A Decline In Flying Insects

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When was the last time you used a squeegee to remove squashed insects from your windshield?  It’s been a while, right?  It’s not just you.  This is known as the windscreen phenomenon.  Scientists and some motorists have long suspected that flying insects are in dramatic decline.  New research has confirmed these suspicions.

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National Parks Are Too Popular

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National Parks are often thought of as America’s natural cathedrals – serene places we visit to commune with nature and soak up its grandeur.   Millions of Americans and other people from around the world are drawn to these amazing places.  Unfortunately, it is now too many millions.

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Trees Are Not Enough

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Trees are nature’s way of removing carbon dioxide from the atmosphere.  Growing plants take up CO2 and store it in the form of their roots, stems and leaves.  And in fact, a significant factor in the growing levels of carbon dioxide in the atmosphere has been the extensive deforestation that has gone on over the past couple of centuries.

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