Biodiversity Conservation Miscellany Phenology

The Sky at Night

Light pollution seems an odd thing for us to be worried about but a growing body of research suggests too much light at night can cause harm to plants, wildlife and even us humans.

Composite view of Earth at night from the Suomi NPP satellite in polar orbit 512 miles above the surface, from April 18, over nine days and for 13 days ending October 23, 2012. Source NASA-NOAA Satellite Reveals New Views of Earth at Night.

A good place to start our exploration is with Terri-Lee Reid’s blog post on the Canadian Wildlife Federation website. She notes that migratory birds are especially vulnerable to striking lit windows at night. All too often these widow strikes are fatal to the birds. So much so that Fatal Light Awareness Program (FLAP) Canada has developed a whole program to educate the public in general and building managers in particular. You’d think the opportunity to turn off lights at night and save money and birds would be an easy win-win. Sadly this is not always the case.

This long-exposure photo shows insects attracted to a streetlight. Photo by Nevit Dilmen/Wikimedia Commons (CC BY-SA 3.0)

Light pollution upending the natural world

Writing in The National Observer earlier this month, Sarah Scoles reviews Johan Eklöf’s new book “The Darkness Manifesto”. In the book, Eklöf describes an evening deep inside Malaysia’s Krau Wildlife Reserve. “One evening, during dinner, one of the film crew’s large lights was left on, directed up toward the sky,”. Lured into the tight column of illumination, a “heavy stream” of the forest’s winged inhabitants “danced in a spiral down toward the light,” he writes. According to Eklöf, this is known as the “vacuum cleaner effect,” and it’s just one way artificial light has a profound effect on the natural world.

The nocturnal illumination that sustains our modern existence seems to disrupt the lives, and circadian rhythms, not just of insects but of animals as varied as bats, birds, plants, turtles, coral, and clownfish (AKA Nemo). Eklöf, a bat researcher and self-proclaimed “friend of the darkness,” is concerned about the cascading ecological effects of what he and other experts call light pollution. In 42 short and digestible chapters, he makes the case that light pollution is a crucial feature of the Anthropocene Epoch. The seeds of light pollution were sowed more than 150 years ago. Artificial light, according to Eklöf, accounts for 10% of our energy use, but just a fraction is actually useful. “Badly directed and unnecessarily strong lights cause pollution that is equivalent to the carbon dioxide emissions of nearly 20 million cars,” he writes.

Scientific research into how light pollution has affected life on Earth is still relatively sparse but drops in insect populations are one example. “The reasons for insect death are many, from urbanization and global warming to the use of insecticides, large-scale farming, single-crop cultivation, and disappearing forests,” writes Eklöf. “But for anyone who’s ever seen an insect react to light, it is obvious that light pollution is a major cause.” Around half of insects are nocturnal and use the dark hours to feed and find reproductive partners. “The night’s limited light protects these insects, and the pale glow from stars and the moon is central for their navigation and hormonal systems,” Eklöf writes.

As for bats, they hunt nocturnal insects, of course, while using the cover of darkness to hide from predators. Particularly in Eklöf’s home country of Sweden,  bats live in church towers. In the 1980s, he writes, two-thirds of churches in southwest Sweden had their own personal bat colonies. But Eklöf’s own research suggests that number has dropped by a third. “The churches all glow like carnivals in the night,” he writes. “All the while the animals — who have for centuries found safety in the darkness of the church towers and who have for 70 million years made the night their abode — are slowly but surely vanishing from these places.”

Artificial light also disrupts humans. Most of us cannot see the stars at night, or the Northern Lights. Artificial light disrupts our bodies’ production of melatonin, the hormone that helps control the sleep cycle, with profound effects on our natural sleeping rhythm, writes Eklöf. “We may not be able to cure or prevent depression all at once by cutting down on electric lighting,” he maintains, “but we definitely increase the chances of good sleep in the long run.”

A fleet of Internet Star Link satellites in orbit above Earth. Scientists worry about their impact. Photo: Shutterstock

Satellite ‘Mega-Constellations’

Writing in Explorersweb, Andrew McLemore explores the conundrum: is it better to look up at the night sky or down at our phones? Driven by private companies, there is a movement to surround Earth with brightly lit machines. It is ostensibly about connection, bringing 5G cell service to every corner of the globe. Yet many scientists and astronomers have begun vocalizing their opposition to telecommunications networks that block our view of the final frontier. Light from satellites has begun interfering with the Hubble telescope, prompting astronomers to consider moving it further into space and away from the visual noise. Lovers of the outdoors want to preserve a natural view of the sky — uninterrupted by the streaks of satellites now more common than shooting stars. In a moving polemic published in the Ecological Citizen this month, scientist Kate McFarland made an environmental argument, positing that increased brightness at night could threaten delicate ecosystems throughout the planet. Unlike the light pollution of a metropolis like LA, the brightness created by satellites can’t be avoided by driving to the Nevada desert.

Two night scenes. On the left, stars fill the sky over the Coconino National Forest. (Credit: Coconino National Forest, U.S. Forest Service.) On the right, a dark sky covers a brightly-lit Los Angeles. (Credit Douglass Clem, CC BY-SA 3.0.)

Turning on the night sky

Writing in News Decoder, which aims at children and educators, Tira Shubart outlines the challenges of night-time lighting and how it interferes with the natural world and our view of the stars. At the end of this piece, she asks her young readers to look at local artificial lighting and how it impacts their neighbourhood and what they can see at night.

A comparison of sodium lights (on the left) and white LEDs (on the right). Author provided

LED streetlights

Writing in The Conversation, entomologist Douglas Boyes discussed how the predictable cycles of day and night have become increasingly blurred. Between 2012 and 2016, satellite measurements revealed that the global area polluted by artificial light grew by 2% each year, intruding ever deeper into biodiversity hotspots like tropical forests. In the UK, as in many other countries, older less efficient sodium street lights are being replaced by brighter and more energy efficient LED lighting.

This change in the colour of artificial light is predicted to have major consequences for wildlife. That’s because white LEDs emit light across the entire visible spectrum. The more wavelengths emitted, the greater the diversity of species and biological processes that are likely to be disrupted. For example, insects are known to be more sensitive to shorter, bluer wavelengths of light, which are largely absent from sodium lighting. Biological processes that are controlled by daylight and internal circadian rhythms, such as reproduction, are more likely to be disrupted or prevented by white LEDS.

To test this hypothesis, Boyes worked with a team of researchers from the UK Centre for Ecology & Hydrology, Newcastle University and Butterfly Conservation, I searched the Thames Valley area for roadsides with both lit and unlit habitats. Around 500 potential locations were whittled down to only those that were more or less identical – apart from the presence of street lighting.

The results, published in Science Advances, were striking. Lighting reduced the numbers of caterpillars by between one half and one third. Lit areas almost universally had lower numbers than their darker counterparts. Sites with white LEDs also had a steeper reduction in numbers compared to sites with sodium lamps. They suspect the reason there were fewer caterpillars in lit areas was because the lighting prevented females from laying eggs, a behaviour that has evolved in darkness. In addition, adult moths can be drawn up to streetlights, where they’re easy pickings for bats. Their recent review article revealed many other plausible mechanisms through which lighting could cause population declines throughout the moths’ life cycles.

I was saddened to learn that Dr. Boyes passed away shortly after this article was written. My deepest condolences to his family, friends and colleagues.

Ynys Enlli (Bardsey Island), north Wales has today (23.02.2023) received International Dark Sky Sanctuary certification by the International Dark Skies Association (IDA).STEVE PORTER

Europe’s First ‘Dark Sky Sanctuary’ is in Wales

To end this post on a more hopeful note, Jamie Carter, Senior Contributor at Forbes, writes about one of few places in the world where an immaculate dark sky is stuffed with stars while the night air is filled with spooky rasping screams. Just two miles long by half a mile wide, the island of Ynys Enlli two miles off the west coast of North Wales has been named an International Dark Sky Sanctuary—only the 17th in the world and the first in Europe—by the International Dark-Sky Association.

What we can do

The International Dark Sky Association recommends that we can take action, including:

  • Assessing the lighting around your home.
  • Using dark sky friendly lighting at your home and business.
  • Talking to your friends, family, and neighbors.
  • Spreading the word online!
  • Becoming a community scientist.
  • Advocating for a lighting ordinance in your town.
  • Visiting an International Dark Sky Place!
Climate Change Gardening

2023 Climate Change Round-up

Photo credit: Markus Spiske on Pexels.

It’s hard to stay on top of all the news about climate change and hard to stay optimistic when so much of it seems to be doom and gloom. I take hope from the ongoing work of so many scientists and activists, and from the success of previous international treaties. For example, earlier this month, the UN reported that the Ozone layer may be restored in decades. The Montreal Protocol, signed in 1987, had countries agree to phase out production and use of ozone-depleting substances. If we could agree globally to save the ozone layer, I think we have a shot at a global agreement to save the entire planet from climate change. Here are a few more reports and news snippets of interest to gardeners.

From the NASA website on global climate change. Photo credits: left – Mellimage/, center – Montree Hanlue/, right – NASA.

The New Yorker reviews Three Climate Reports: The Good, the Bad, and the Ugly. The good: the Biden Administration released an 83-page “blueprint” for decarbonizing the nation’s transportation systems, which are that country’s largest source of carbon emissions. The bad: the Rhodium Group, an independent research firm, estimated that US greenhouse-gas emissions grew by 1.3% in 2022, largely due to an increase in emissions from the transportation sector. This increase, according to the report, “was driven mainly by the demand for jet fuel,” as air travel rebounded from COVID. On the positive side, renewables now produce more electricity than coal in the U.S., and total emissions are still slightly lower than pre-pandemic levels in 2019. However, the US is falling ever further behind on its commitments. Last summer’s passage of the Inflation Reduction Act, which authorizes some $400B in spending on clean energy, was a “turning point,” and could produce emissions cuts “as early as this year if the government can fast-track implementation.” Still, the group admonished, the U.S. “needs to significantly increase its efforts.” The ugly is the third report, from the European Union’s Copernicus Climate Change Service, which notes that 2022 was the fifth-warmest year on record globally, and last summer in Europe “was the warmest on record by a clear margin.” In fact, , all of the past eight years have been among the eight hottest. 

A rainbow above the Washington Monument on the National Mall in Washington, D.C. Photographer: Samuel Corum/Bloomberg

Bloomberg offers a rosier perspective behind their paywall in an article by Leslie Kaufman and Laura Millan Lombrana called Six Climate Breakthroughs That Made 2022 a Step Toward Net Zero. They begin by acknowledging the almost incomprehensible damage wrought by climate change, and distressing policy decisions, such as rebounds in coal consumption. But they also note the following signs of hope:

  • The Biden administration’s Inflation Reduction Act, which is the country’s most aggressive piece of climate legislation ever. Its provisions ensure that for decades to come billions of dollars will roll toward the energy transition, making it easier to deploy renewable energy, build out green technologies and subsidize consumer adoption of sustainable technologies.
  • The European Union started to make good on its pledge to cut emissions by introducing additional costs imposed on imported goods from countries without the EU’s restrictions on planet-warming pollution.
  • Agreement at COP15 helps to protect biodiversity.
  • The big breakthrough at the 2022 climate negotiations (COP27 in Egypt) sees developed countries agreeing to fund loss, damage and energy transition for developing nations.
  • Voters in Brazil ousted Bolsonaro and reinstated Luiz Inacio Lula da Silva, who won the presidency in part by promising to stop deforestation of the Amazon. Pro-climate parties also won big in Australia’s elections.
  • Following the recognition at COP26 in Glasgow of the dangers of methane, a powerful greenhouse gas, 150 countries have pledged to act to reduce methane emissions.
Prosopis laevigata mesquite near the Chichimeco dam, in Jesús María, Aguascalientes, Mexico. Photo by Luis Alvaz, from Wikipedia.

Climate Change May Favor Nitrogen-Fixing Plants

In Death Valley National Park, which straddles the California-Nevada border, mesquite plants (genus Prosopis) thrive in extreme aridity. While most vegetation types must extract most of their nutrients from fertile soil, mesquites and similar plants receive additional nitrogen from symbiotic bacteria, which enzymatically fix atmospheric nitrogen into an easily absorbed form in exchange for sugars produced during photosynthesis. To determine how arid conditions affect the biodiversity of these types of nitrogen-fixing plants, University of Florida PhD student Josh Doby compared public data on soil, species counts, and aridity from 47 terrestrial sites in the US. Doby and his colleagues initially hypothesized that nitrogen-deficient soils would prompt an increase in nitrogen-fixing plant diversity. The results, however, showed “that aridity is actually the primary driver” of phylogenetic diversity, Doby says. As conditions became drier, the ratio of nitrogen-fixing to non-fixing plant species increased even as overall plant diversity declined. Because these plants have access to atmospheric nitrogen from their symbiotic bacteria, their leaves contain more nitrogen than other plants, and this buffers them against aridity by helping them retain water, says Mark Adams, an ecologist at the Swinburne University of Technology in Australia who was not involved in this research. When plants open their stomata to take in carbon dioxide, water escapes, but nitrogen stimulates the production of enzymes that improve the efficiency of carbon uptake, shortening how long plants need to hold their stomata open, Adams explains. “And that’s the secret [of] nitrogen-fixing plants.” Doby’s research is published in the journal Global Ecology and Biogeography.

A dust storm. Photograph: Jason Davies/Severe Weather Australia

‘It was like an apocalyptic movie’: 20 climate photographs that changed the world: The Guardian UK offers recent  images that change how we see our world and how we understand climate change. From the iconic 1968 “Earthrise” photo that is credited with kick-starting the environmental movement to pictures of golfers “playing through” a forest fire in Oregon; a man pushing kids on a satellite dish through floods in Pakistan; and deforestation in the Amazon, these photos bring home the reality of climate change. Note, images of giraffes that died of thirst in Kenya and a starving polar bear are particularly upsetting.

Leaf them be. Photo by R. Last.

After those sobering images from The Guardian, it’s time for some more positive news. A recent Danish studies found that By leaving garden waste alone, Danes could store 600,000 tons of carbon dioxide per year. This is wonderful news for those of us who already practice ecological gardening because there are so many other advantages to leaving garden waste where it lies. For example, fall leaf litter protects a multitude of over-wintering invertebrates. And of course, leaving the yard waste in place is much less work for us gardeners. Talk about a win-win-win!

Rhodo in Rebecca’s back yard. Photo by R. Last.

Climate crisis prompts RHS to plan for sending rhododendrons north

In an example of assisted plant migration, the Guardian reports that the climate crisis has prompted the Royal Horticultural Society to plan a move of its important collection of rhododendrons from its flagship Wisley garden in Surrey to Harlow Carr in North Yorkshire.

Visual abstract. Effect of climate change–impact menu labels on fast food ordering choices. Credit: JAMA Network Open (2022). DOI: 10.1001/jamanetworkopen.2022.48320

In the category of things we can do, pushing for climate labelling just might be a good avenue to explore. A recent Study shows climate impact labels on food sold in fast food restaurants can change buying habits. A team of researchers affiliated with multiple institutions in the U.S. has found that placing labels on foods sold at fast food restaurants informing consumers of the negative impact of the production of such foods on the planet can alter consumer buying habits. In their paper published on JAMA Network Open, the group describes conducting an online survey using a fictional restaurant to learn more about consumer food buying choices.

From The Guardian, a wind farm in Texas. Photograph: Delcia Lopez/AP

Finally, in a lengthy piece in The Guardian, Rebecca Solnit writes that “Every crisis is in part a storytelling crisis.” Her article about how to tell the story of climate change (‘If you win the popular imagination, you change the game’: why we need new stories on climate) offers hope for new story-telling and useful tips on how to talk about climate change with your friends.