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By Ruby Russell
It was only in the mid-20th century, in the wake of the shattering impact of World Wars and when capitalism and communism were competing for global dominance, that we began to measure the success of an economy in terms of gross national product, or GDP.
The faster GDP was rising, the better an economy could be said to be performing. But something happens as all that economic activity expands. The amount of energy and resources we use also increase.
Ever since the industrial revolution, fossil fuels have set us on a course of furiously expanding production, which has also meant more waste and more pollution. Historically, greenhouse gas emissions have risen alongside GDP. As economies have grown richer, nature has paid the price.
And as the climate crisis has become ever-harder to ignore, more people are questioning whether infinite economic growth is possible on a planet of finite resources.
Zero-Emissions With Twice the GDP
"The Intergovernmental Panel on Climate Change in their Fifth Assessment, have 116 mitigation scenarios with a chance of staying below the 2 degree Celsius threshold. All of those scenarios assume 2-3% GDP growth rates," says Jon Erickson, an ecological economist at the Gund Institute for Environment in Vermont, adding that this implies doubling the global economy by somewhere around 2050.
These scenarios rely not just on switching to renewables, but also on the large-scale extraction of massive volumes of carbon from the atmosphere using as-yet unproven technology, which Erickson describes as "wildly unrealistic."
"None of those models and the IPCC community even bother simulating a scenario where the global economy contracts, stabilizes and maybe even degrows," Erickson says. "Yet that's probably the one realistic scenario that would significantly affect greenhouse gas emissions."
It is easy to see why the idea that we must keep growing is hard to give up. When economic activity declines and we go into recession, people lose their jobs and are plunged into poverty.
Yet those arguing for "degrowth" — a managed contraction of economic activity— say it doesn't have to be this way.
Time for a Different Approach?
Federico Demaria, an economist at the Autonomous University of Barcelona, who has authored several books on degrowth, says that neoclassical economics — which has dominated economic discourse over recent decades, has "never looked at the question of how an economy could be managed without growth. It only looked at questions like, why do economies grow? If it's not growing, how can we make it grow? Or, how can we make it grow even faster?"
These have become pertinent questions even — or especially — for wealthy, industrialized economies, where growth has slowed over recent decades. "What the mainstream economists are doing is just trying to relaunch growth," Demaria says.
A different approach, which aims to rein in growth without inflicting the pain that recession has traditionally entailed, comes from the field of ecological economics.
Embedding Economics in Ecology
Neoclassical economic models picture economies as closed systems, with no inputs of materials or energy and no outputs of pollution and waste. But ecological economists insist there is no real separation between economy and ecology. After all, if we destroy the planet that feeds us, economic activity will collapse pretty quickly too.
In an effort to fix this oversight, Demaria is among those devising new economic models that include factors like emissions and resources use. They are also working in things like social equality, debt, deficits and monetary systems, which have social impacts, and play into cycles of boom and bust.
Which is why Demaria says their work is attracting attention from surprising quarters.
"The main idea of ecological macroeconomics is that the economy is embedded into the environment," he says. "The second problem is that the neoclassical models were not realistic — look at the financial crisis; they didn't see it coming because they were completely unable to model it. So central banks, for example, are showing a lot of interest in ecological macroeconomics."
Degrowth Vs. Green Growth
Yet mainstream environmentalism is still firmly entrenched in the idea of "green growth."
The IPCC, the World Bank, the OECD and countless think tanks and national governments rely on us being able to "decouple" growth from its ecological impact. And some economies, like Germany, have grown while emissions level off, or even decline.
Countless scientific papers have been dedicated to the fierce debate over whether these cases represent an absolute break or just a tempering of the link between growth, emissions and resource-use.
But proponents of degrowth argue that to date, decoupling has only happened in wealthy economies that have outsourced emissions-heavy sectors like manufacturing to economies like China, and that globally the correlation is still strong.
As exemplified by the IPCC scenarios, the argument for "green growth" rests on the assumption that technology will save us. By recycling more, swapping energy from fossil fuels to that from renewables, and improving efficiency so we need less of it overall, proponents of green growth hope to keep expanding without sacrificing our planet's ability to feed us and maintain a stable climate.
Increased Efficiency, Greater Energy Use
Yet technological advances don't always have the desired outcome.
When new engines that needed less coal to produce the same amount of energy were introduced in the 19th century, coal consumption didn't fall. Instead, better efficiency increased profits, made products cheaper, and drove up demand, meaning coal use actually went up.
This trend — called Jevons paradox — has persisted, meaning that improvements in efficiency tend to come with a rebound effect that wipes out any actual energy savings. Similar effects can be seen in resource use, and even labor, as automation has done more to boost consumption and production than free time for workers.
In a system geared toward infinite expansion, opportunities to tighten our belts tend to be seized as new ways to keep getting bigger.
But degrowthers argue that we do have to tighten our belts — and it doesn't have to be painful. If we could reverse the central logic of economic systems that prioritize growth over human and ecological wellbeing, they don't believe we would miss the furious activity that's keeping a minority of the human population in must-have products and ever-more material wealth.
This article is part of our series How do we change? Click here to explore more big ideas to transform our understanding of the ecological crisis.
Reposted with permission from Deutsche Welle.
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EcoWatch Daily Newsletter
By Jim Palardy
As 2021 dawns, people, ecosystems, and wildlife worldwide are facing a panoply of environmental issues. In an effort to help experts and policymakers determine where they might focus research, a panel of 25 scientists and practitioners — including me — from around the globe held discussions in the fall to identify emerging issues that deserve increased attention.
Ask a Scientist: What Should the Biden Administration and Congress Do to Address the Climate Crisis?
By Elliott Negin
What a difference an election makes. Thanks to the Biden-Harris victory in November, the next administration is poised to make a 180-degree turn to again address the climate crisis.
- Biden Reaffirms Commitment to Rejoining Paris Agreement ... ›
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By Suresh Dhaniyala and Byron Erath
A fast-spreading variant of the coronavirus that causes COVID-19 has been found in at least 10 states, and people are wondering: How do I protect myself now?
Airborne Particles Are Still the Biggest Problem
<p>The <a href="https://theconversation.com/why-it-matters-that-the-coronavirus-is-changing-and-what-this-means-for-vaccine-effectiveness-152383" target="_blank" rel="noopener noreferrer">SARS-CoV-2 variants</a> are believed to spread primarily through the air rather than on surfaces.</p><p>When someone with the coronavirus in their respiratory tract coughs, talks, sings or even just breathes, infectious respiratory droplets can be expelled into the air. These droplets are tiny, predominantly in the range of <a href="https://www.sciencedirect.com/science/article/pii/S0021850211001200?casa_token=KtyrsEfbeqcAAAAA:vv10sSxm33tzg0EQvNMIFtV7GCu5gE9QAzuyzHKr2_4Cl0OFkUJoGwzn4d0ZnEWS19NsOTuH" target="_blank" rel="noopener noreferrer">1-100 micrometers</a>. For comparison, a human hair is about 70 micrometers in diameter.</p><p>The larger droplets fall to the ground quickly, rarely traveling farther than 6 feet from the source. The bigger problem for disease transmission is the tiniest droplets – those less than 10 micrometers in diameter – which can remain suspended in the air as aerosols for <a href="https://academic.oup.com/cid/article/50/5/693/325466" target="_blank">hours at a time</a>.</p><span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="bb67b83dcafe589f350daf3df60fa29d"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/UNCNM7AZPFg?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Daily case reports and 7-day rolling average as of Jan. 16, 2021.Chart: The Conversation, CC-BY-ND Source: COVID Tracking Project Get the data
What Can You Do to Stay Safe?
<p>1) Pay attention to the type of face mask you use, and how it fits.</p><p>Most off-the-shelf face coverings are not 100% effective at preventing droplet emission. With the new variant spreading more easily and likely infectious at lower concentrations, it's important to select coverings with materials that are most effective at stopping droplet spread.</p><p>When available, N95 and surgical masks consistently perform the best. Otherwise, face coverings that use <a href="https://www.sciencedirect.com/science/article/pii/S2352431620301802?casa_token=-Dj6nGBAm24AAAAA:qq9BpbzCKaPDFcV73ohA2fCnhE_Zlkss6Bei3kUwq9QYndhHj0Vafbbd-ef_855lx6knDfUt" target="_blank">multiple layers of material</a> are preferable. Ideally, the material should be a tight weave. High thread count cotton sheets are an example. Proper fit is also crucial, as gaps around the nose and mouth can <a href="https://pubs.acs.org/doi/10.1021/acsnano.0c03252" target="_blank" rel="noopener noreferrer">decrease the effectiveness by 50%</a>.</p><p>2) Follow social distancing guidelines.</p><p>While the current social distancing guidelines are not perfect – <a href="https://theconversation.com/what-a-smoky-bar-can-teach-us-about-the-6-foot-rule-during-the-covid-19-pandemic-145517" target="_blank" rel="noopener noreferrer">6 feet isn't always enough</a> – they do offer a useful starting point. Because aerosol concentrations levels and infectivity are highest in the space immediately surrounding anyone with the virus, increasing physical distancing can help reduce risk. Remember that people are infectious <a href="https://medical.mit.edu/faqs/COVID-19#faq-10" target="_blank" rel="noopener noreferrer">before they start showing symptoms</a>, and they many never show symptoms, so don't count on seeing signs of illness.</p><p>3) Think carefully about the environment when entering an enclosed area, both the ventilation and how people interact.</p><p>Limiting the size of gatherings helps reduce the potential for exposure. Controlling indoor environments in other ways can also be a highly effective strategy for reducing risk. This includes <a href="https://theconversation.com/what-a-smoky-bar-can-teach-us-about-the-6-foot-rule-during-the-covid-19-pandemic-145517" target="_blank" rel="noopener noreferrer">increasing ventilation rates</a> to bring in <a href="https://theconversation.com/keeping-indoor-air-clean-can-reduce-the-chance-of-spreading-coronavirus-149512" target="_blank" rel="noopener noreferrer">fresh air and filtering existing air</a> to dilute aerosol concentrations.</p><p>On a personal level, it is helpful to pay attention to the types of interactions that are taking place. For example, many individuals shouting can create a higher risk than one individual speaking. In all cases, it's important to minimize the amount of time spent indoors with others.</p><p>The CDC has warned that B.1.1.7 could <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7003e2.htm?s_cid=mm7003e2_w" target="_blank" rel="noopener noreferrer">become the dominant SARS-CoV-2 variant</a> in the U.S. by March. Other fast-spreading variants have also been found in <a href="https://virological.org/t/genomic-characterisation-of-an-emergent-sars-cov-2-lineage-in-manaus-preliminary-findings/586" target="_blank" rel="noopener noreferrer">Brazil</a> and <a href="https://www.who.int/csr/don/31-december-2020-sars-cov2-variants/en/" target="_blank" rel="noopener noreferrer">South Africa</a>. Increased vigilance and complying with health guidelines should continue to be of highest priority.</p>- FDA Approves First In-Home Test for Coronavirus - EcoWatch ›
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By Tara Lohan
A key part of the United States' clean energy transition has started to take shape, but you may need to squint to see it. About 2,000 wind turbines could be built far offshore, in federal waters off the Atlantic Coast, in the next 10 years. And more are expected.
Threats to Birds
<p>One of the gravest threats facing birds is climate change, according to Audubon, which found that rising temperatures threaten <a href="https://www.audubon.org/2019climateissue" target="_blank" rel="noopener noreferrer">nearly two-thirds of North America's bird species</a>. That's why the impending development of offshore wind is a good thing, says Shilo Felton, a field manager in the organization's Clean Energy Initiative, but it also comes with dangers to birds that need to be better studied and mitigated.</p><p>The most obvious risk comes from birds colliding with spinning turbine blades. But offshore wind developments can also displace birds from foraging or roost sites, as well as migratory pathways.</p><p>Along the Atlantic Coast four imperiled species are of top concern to conservationists: the endangered piping plover, red knot, roseate tern and black-capped petrel, which is being considered for listing under the Endangered Species Act.</p><p>"Those four species are of utmost importance to make sure that we understand the impacts," says Felton. "But beyond that there are many species that are protected under the Migratory Bird Treaty Act and the Fish and Wildlife Conservation Act that could potentially see more impacts from offshore wind."</p><p>Northern gannets, for example, are at risk not just for collision but <a href="https://www.researchgate.net/publication/308703197_Possible_impacts_of_offshore_wind_farms_on_seabirds_a_pilot_study_in_Northern_Gannets_in_the_southern_North_Sea" target="_blank">habitat displacement</a>.</p>A northern gannet flying along Cape May, N.J. Ann Marie Morrison / CC BY-NC-ND 2.0
<p>"There's <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320716303196" target="_blank">some evidence</a> that they just won't use areas where turbines are, but that also excludes them from key foraging areas," says Felton. Researchers are still studying what this may mean for the birds. But a <a href="https://www.sciencedirect.com/science/article/pii/S0141113620305304" target="_blank">study</a> published in December 2020 conducted at Bass Rock, Scotland — home to the world's largest northern gannet colony — found that wind developments could reduce their growth rate, though not enough to cause a population decline.</p><p>Other birds, such as great cormorants and European shags, are <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320716303196" target="_blank">attracted to wind developments</a> and use the infrastructure to rest while opening up new foraging areas farther from shore.</p><p>"There's plenty of potential for a bird to use a wind farm and still to avoid the turbines themselves," says Felton.</p><p>Birds like pelicans, however, are less versatile in their movements and are at particular risk of collision because of their flight pattern, she says.</p><p>But how disruptive or dangerous offshore turbines will be along the East Coast isn't yet known.</p><p>Federal and state agencies, along with nongovernmental organizations, says Felton, have done good research to try to better understand those potential impacts. "But these are all theoretical, because we don't have a lot of offshore wind yet in the United States."</p>Threats to Ocean Life
<p>Birds aren't the only wildlife of concern. More development in ocean waters could affect a litany of marine species, some of which are already facing other pressures from overfishing, pollution, habitat destruction and climate change.</p><p>Scientists have found that marine mammals like whales and dolphins could be disturbed by the jarring sounds of construction, especially if pile driving is used to hammer the steel turbine platform into the seafloor.</p><p>The noises, though short-lived, could impede communication between animals, divert them from migration routes or cause them to seek less suitable areas for feeding or breeding. Research from Europe found that harbor porpoises, seals and dolphins may avoid development areas during construction. In most, but <a href="https://iopscience.iop.org/article/10.1088/1748-9326/7/4/045101" target="_blank">not all cases</a>, the animals were believed to have returned to the area following construction.</p><p>The biggest concern for conservation groups in the United States is the critically endangered North American right whale. There are fewer than 400 remaining, and the species' habitat overlaps with a number of planned wind development areas along the East Coast.</p><p>"Offshore wind is in no way the cause of the challenges the whales face, but it's going to be another pressure point," says John Rogers, senior energy analyst for the Union of Concerned Scientists.</p><p>Researchers aren't sure how right whales will respond to the noise from pile driving.</p><p>"But we are concerned, based on what we know about how whales react to other noise sources, that they may avoid [wind development] areas," says Kershaw.</p><p>And if that displacement causes them to miss out on important food resources, it could be dangerous for a species already on the brink.</p><p>There are a few other potential threats, too.</p><p>Ships associated with the development — more plentiful during construction — also pose a danger. In the past few years cargo ships, fishing boats and other vessels have caused half of all deaths of North Atlantic right whales.</p>A juvenile right whale breaches against the backdrop of a ship near the St. Johns River entrance. Florida Fish and Wildlife Conservation Commission / NOAA Research Permit #775-1600-10
<p>And after construction, the noise from the spinning turbines will be present in the water at low decibels. "We don't quite know how the great whales will react to those sounds," says Jeremy Firestone, the director of the Center for Research in Wind at the University of Delaware.</p><p>Other marine mammals may also perceive the noise, but at low decibels it's unlikely to be an impediment, <a href="http://www.int-res.com/abstracts/meps/v309/p279-295/" target="_blank">research has found</a>.</p><p>And it's possible that wind development could help some ocean life. Turbine foundations can attract fish and invertebrates for whom hard substrates create habitat complexity — known as the "reef effect," according to researchers from the University of Rhode Island's <a href="https://dosits.org/animals/effects-of-sound/anthropogenic-sources/wind-turbine/" target="_blank" rel="noopener noreferrer">Discovery of Sound in the Sea</a> program. Exclusion of commercial fishing nearby may also help shelter fish and protect marine mammals from entanglements in fishing gear.</p>Ensuring Safe Development
<p>Despite the potential dangers, researchers have gathered a few best practices to help diminish and possibly eliminate some risks.</p><p>When it comes to ship strikes, the easiest thing is to slow boats down, mandating a speed of <a href="https://biologicaldiversity.org/w/news/press-releases/vessel-speed-limits-sought-protect-endangered-north-atlantic-right-whales-2020-08-06/" target="_blank">10 knots</a> in wind development areas, and using visual and acoustic monitoring for whales.</p><p>Adjusting operations to reduce boat trips between the shore and the wind development will also help. A new series of service operating vessels can allow maintenance staff to spent multiple days onsite, says Kershaw, cutting down on boat traffic.</p><p>For construction noise concerns, developers can avoid pile driving during times of the year when whales are present. And, depending on the marine environment, developers could use "quiet foundations" that don't require pile driving. These include gravity-based or suction caisson platforms.</p><p>Floating turbines are also used in deep water, where they're effectively anchored in place — although that poses its own potential danger. "We have concerns that marine debris could potentially become entangled around the mooring cables of the floating arrays and pose a secondarily entanglement risk to some species," says Felton, who thinks more research should be conducted before those become operational in U.S. waters — a process that's already underway in Maine, where a <a href="https://composites.umaine.edu/2020/08/05/diamond-offshore-wind-rwe-renewables-join-the-university-of-maine-to-lead-development-of-maine-floating-offshore-wind-demonstration-project/" target="_blank" rel="noopener noreferrer">demonstration project is being built</a>.</p><p>If loud noises are unavoidable during construction, noise-reducing technologies such as bubble curtains can help dampen the sound. And scheduling adjacent projects to conduct similar work at the same time could limit the duration of disturbances.</p>The foundation installation of the off shore wind farm Sandbank using a bubble curtain. Vattenfall / Ulrich Wirrwa / CC BY-NC-ND 2.0
<p>Once turbines become operational, reducing the amount of light on wind platforms or using flashing lights could help deter some seabirds, NRDC <a href="https://www.nrdc.org/sites/default/files/harnessing-wind-advance-wind-power-offshore-ib.pdf" target="_blank" rel="noopener noreferrer">researchers reported</a>. And scientists are exploring using ultrasonic noises and ultraviolet lighting to keep bats away. "Feathering," or shutting down the turbine blades during key migration times, could also help prevent fatalities.</p><p>"We need to make sure that offshore wind is the best steward it can be of the marine ecosystem, because we want and expect it to be a significant part of the clean energy picture in some parts of the country," says Rogers. "We also have to recognize that we're going to learn by doing, and that some of these things we're going to figure out best once we have more turbines in the water."</p><p>That's why environmental groups say it's important to establish baseline information on species before projects begin, and then require developers to conduct monitoring during construction and for years after projects are operational.</p><p>Employing an "adaptive management framework" will ensure that developers can adjust their management practices as they go when new information becomes available, and that those best practices are incorporated into the requirements for future projects.</p>Putting Research Into Action
<p>Advancing these conversations at the federal level during the Trump administration, though, has been slow going.</p><p>"We didn't really have any productive discussions with the administration in the last four years," says Kershaw.</p><p>And when it comes to birds, Felton says the Bureau of Ocean Energy Management's recently completed "draft cumulative environmental impact statement" covering offshore wind developments had a lot of good environmental research, but little focus on birds.</p><p>"Part of that comes from the current administration's interpretation of the Migratory Bird Treaty Act," she says.</p><p>President Trump has been hostile to both wind energy <em>and</em> birds, <a href="https://www.nytimes.com/2021/01/05/climate/trump-migratory-bird-protections.html" target="_blank">and finished gutting the Migratory Bird Treaty Act</a> in his administration's the final days, removing penalties for companies whose operations kill migratory birds.</p><p>There's hope that the Biden administration will take a different approach. But where the federal government has been lacking lately, Kershaw says, they've seen states step up.</p><p>New York, for example, has established an <a href="https://www.nyetwg.com/" target="_blank" rel="noopener noreferrer">Environmental Technical Working Group</a> composed of stakeholders to advise on environmentally responsible development of offshore wind.</p><p>The group is led by the New York State Energy Research and Development Authority, but it isn't limited to the Empire State. It's regional in focus and includes representatives from wind developers with leases between Massachusetts and North Carolina; state agencies from Massachusetts to Virginia; federal agencies; and science-based environmental NGOs.</p><p>New York's latest solicitation for clean energy projects includes up to 2,500 megawatts of offshore wind and <a href="https://www.nyetwg.com/announcements" target="_blank" rel="noopener noreferrer">requires developers</a> to contribute at least $10,000 per megawatt for regional monitoring of fisheries and other wildlife.</p><p>Environmental groups have also worked directly with developers, including an agreement with Vineyard Wind — an 800-megawatt project off the Massachusetts coast that could be the first utility-scale wind development in federal waters — to help protect North Atlantic right whales.</p><p>The agreement includes no pile driving from Jan. 1 to April 30, ceasing activities at other times when whales are visually or acoustically identified in the area, speed restrictions on vessels, and the use of noise reduction technology, such as a bubble curtain during pile driving.</p><p>"The developers signed the agreement with us, and then they incorporated, most, if not all of those measures into the federal permitting documents," says Kershaw. "The developers really did a lot of bottom up work to make sure that they were being very protective of right whales."</p><p>Environmental groups are in talks with other developers on agreements too, but Felton wants to see best practices being mandated at the federal level.</p><p>"It's the sort of a role that should be being played by the federal government, and without that it makes the permitting and regulation process less stable and less transparent," she says." And that in turn slows down the build out of projects, which is also bad for birds because it doesn't help us address and mitigate for climate change."</p><p>Kershaw agrees there's a lot more work to be done, especially at the federal level, but thinks we're moving in the right direction.</p><p>"I think the work that's been done so far in the United States has really laid the groundwork for advancing this in the right way and in a way that's protective of species and the environment," she says. "At the same time, it's important that offshore wind does advance quickly. We really need it to help us combat the worst effects of climate change."</p><p><em><a href="https://therevelator.org/author/taralohan/" target="_blank" rel="noopener noreferrer">Tara Lohan</a> is deputy editor of The Revelator and has worked for more than a decade as a digital editor and environmental journalist focused on the intersections of energy, water and climate. Her work has been published by The Nation, American Prospect, High Country News, Grist, Pacific Standard and others. She is the editor of two books on the global water crisis.</em></p><p><em style="">Reposted with permission from <a href="https://therevelator.org/offshore-wind-wildlife" target="_blank" style="">The Revelator</a>. </em></p>- U.S. Offshore Wind Power Blown on Course - EcoWatch ›
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Trending
Cities Can Help Migrating Birds on Their Way By Planting More Trees and Turning Lights Off at Night
By Frank La Sorte and Kyle Horton
Millions of birds travel between their breeding and wintering grounds during spring and autumn migration, creating one of the greatest spectacles of the natural world. These journeys often span incredible distances. For example, the Blackpoll warbler, which weighs less than half an ounce, may travel up to 1,500 miles between its nesting grounds in Canada and its wintering grounds in the Caribbean and South America.
Blackpoll warbler abundance in breeding, non-breeding and migration seasons. Cornell Lab of Ornithology / CC BY-ND
<p>For many species, these journeys take place at night, when skies typically are calmer and predators are less active. Scientists do not have a good understanding yet of how birds navigate effectively at night over long distances.</p><p><span></span>We study bird migration and how it is being affected by factors ranging from <a href="https://scholar.google.com/citations?user=S04C3UMAAAAJ&hl=en" target="_blank">climate change</a> to <a href="https://scholar.google.com/citations?user=pPk38-8AAAAJ&hl=en" target="_blank">artificial light at night</a>. In a recent study, we used millions of bird observations by citizen scientists to document the <a href="https://doi.org/10.1016/j.envpol.2020.116085" target="_blank">occurrence of migratory bird species in 333 U.S. cities</a> during the winter, spring, summer and autumn.</p>Blackpoll warbler. PJTurgeon / Wikipedia
<p>We used this information to determine how the number of migratory bird species varies based on each city's level of <a href="https://www.britannica.com/science/light-pollution" target="_blank" rel="noopener noreferrer">light pollution</a> – brightening of the night sky caused by artificial light sources, such as buildings and streetlights. We also explored how species numbers vary based on the quantity of tree canopy cover and impervious surface, such as concrete and asphalt, within each city. Our findings show that cities can help migrating birds by planting more trees and reducing light pollution, especially during spring and autumn migration.</p>Declining Bird Populations
<p>Urban areas contain numerous dangers for migratory birds. The biggest threat is the risk of <a href="https://doi.org/10.1650/CONDOR-13-090.1" target="_blank">colliding with buildings or communication towers</a>. Many migratory bird populations have <a href="http://dx.doi.org/10.1126/science.aaw1313" target="_blank">declined over the past 50 years</a>, and it is possible that light pollution from cities is contributing to these losses.</p><p>Scientists widely agree that light pollution can <a href="https://doi.org/10.1073/pnas.1708574114" target="_blank">severely disorient migratory birds</a> and make it hard for them to navigate. Studies have shown that birds will cluster around brightly lit structures, much like insects flying around a porch light at night. Cities are the <a href="https://doi.org/10.1002/fee.2029" target="_blank" rel="noopener noreferrer">primary source of light pollution for migratory birds</a>, and these species tend to be more abundant within cities <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13792" target="_blank" rel="noopener noreferrer">during migration</a>, especially in <a href="https://doi.org/10.1016/j.landurbplan.2020.103892" target="_blank" rel="noopener noreferrer">city parks</a>.</p>Composite image of the continental U.S. at night from satellite photos. NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center