The Scientist: Are We in the Midst of a Sixth Mass Extinction?

This picture illustrates a scene from northern Laurentia (North America) in the period a few weeks after the Chicxulub impact showing the onset of freezing weather and skies loaded with sulfur aerosols. The focus is on the last surviving dinosaurs – here a pair of T-Rex chicks, which somehow survived the initial impact phenomena, but which will soon succumb to the cold. Credit: ©James McKay – Creative Commons

“You wouldn’t have lasted long, I don’t think, as a puny human swimming around in this ocean,” muses paleontologist and geologist James Witts while viewing an artist’s depiction of marine life during the Cretaceous Period on his computer screen. Starting around 145 million years ago, this was the last age of the dinosaurs. As on land, the food web of these ancient seas was likely dominated by gigantic reptiles. Along with sharks, many of these now-extinct species may have feasted on bottom-dwelling crustaceans and free-swimming cephalopods and fish. 

Today, the fossilized remains of these creatures are buried beneath a conspicuous layer of sediment or rock that geologists call the Cretaceous-Paleogene (K-Pg) boundary. The layer is typically enriched in the element iridium, released by the shattering of the Mount Everest–sized asteroid that smashed into modern-day Mexico one fateful day 66 million years ago and brought the Cretaceous period to a violent end. “It basically happened in the worst possible place,” says Witts, a lecturer at the University of Bristol. Research published earlier this year by him and his colleagues suggests that massive quantities of sulfur from bedrock at the impact site, in the present-day Yucatán peninsula, were blasted into the atmosphere, creating aerosols that blocked sunlight for several months, cooled the climate for decades, and fell down as acid rain—all contributing to the collapse of global ecosystems. The fossil record falls comparatively silent after the K-Pg boundary, as an estimated 76 percent of marine species were wiped out, for instance. And as life recovered over the next million years, only a subset of the lineages that previously roamed the Earth were among its ranks. Like their popular terrestrial counterparts, “the big marine reptiles—they never come back,” says Witts.  

The K-Pg extinction is the most recent of five events in Earth’s history that scientists consider mass extinctions, defined by paleontologists as events where more than 75 percent of species vanish within a geologically short period of time, typically less than two million years. The four previous mass extinctions were also thought to have involved climatic changes—due to large-scale volcanic eruptions, for example—and in one case obliterated all but 5 percent of species. (See illustration below.) In between these events were smaller extinction episodes and periods of relative stability, with new species often arising at rates that compensated for species losses.  

Now, many scientists fear that the next ordeal of this scale is close—this time around, caused by our species, which sprang onto the scene within the last few hundred thousand years. Although we’re still far away from reaching the 75 percent mark, extinction rates are climbing, and many more species appear to be on the brink. Scientists point to the worldwide destruction of natural habitats and the exploitation of wild species, along with climate change, pollution, and ecological disruption caused by the spread of invasive organisms, as driving factors. Indeed, Witts says he reckons that the sheer speed of environmental change today is similar to that caused by the asteroid. 

Whether current biodiversity loss—a crisis by any measure—meets the criteria for another mass extinction is hotly debated. Much of the debate hinges on accurately measuring the scale of modern-day and prehuman extinction, which is complicated by an incomplete understanding of present and past biodiversity. Some scientists also question whether diagnosing a mass extinction is even relevant. 

“We’re in this really unusual position, where, for the first time, we are trying to put our finger on a geologically superlative event while it’s happening,” says Jacquelyn Gill, a paleoecologist at the University of Maine. However, when it comes to biodiversity loss, “just evoking the fact that our influences could even be on the scale of a comet or some of these other big events in the past—I think that should be giving us pause.” 

Read more at The

Grist: The next climate battle in the courts is over mental health

Image credit: Grist

As a 10th-grader growing up in Bergen, Norway, Mia Chamberlain dreaded when her science class lesson was on climate change. She’d often skip those classes or sneak out of the classroom. She couldn’t handle the fear when confronted with projections of scorching droughts and devastating floods — a future that she would have to live through, despite having grown up in a country as wealthy and safe as Norway. It was like the breathless, stomach-churning feeling of being broken up with, the moment a future vanishes. She couldn’t understand how her science teachers could discuss it with the same detached calm of instructing an algebra class. “It was like sitting through a horror movie that you really don’t want to be watching,” said Chamberlain, who is now 23.

Around that time, nearly 2 million barrels of oil and other fossil fuels were being drilled each day from Norway’s continental shelf, much of it sold elsewhere. Adults around her didn’t seem to understand Chamberlain’s frustration. She felt afraid, lonely, angry, anxious, and deeply unhappy — a tide of emotions she now describes as climate anxiety, a diagnosis that is receiving more and more attention from scientists, psychologists, and now, courts.

Read more at Grist

Knowable Magazine: Climate change is altering the chemistry of wine

Cabernet grapes at the UC Davis Oakville research station in Napa Valley. Credit: Katarina Zimmer

Soon after the devastating Glass Fire sparked in California’s Napa Valley in September 2020, wine chemist Anita Oberholster’s inbox was brimming with hundreds of emails from panicked viticulturists. They wanted to know if they could harvest their grapes without a dreaded effect on their wine: the odious ashtray flavor known as smoke taint.  

Oberholster, of the University of California, Davis, could only tell them, “Maybe.”

Industry laboratories were slammed with grape samples to test, with wait times of up to six weeks. Growers didn’t know whether it was worth harvesting their crops. Eight percent of California wine grapes in 2020 were left to rot.  

Winemakers are no strangers to the vicissitudes wrought by climate change. Warmer temperatures have been a boon to some in cooler regions who are rejoicing over riper berries — but devastating to others. Scorching heat waves, wildfires and other climate-driven calamities have ruined harvests in Europe, North America, Australia and elsewhere. 

And as 2020 showed, climate change can take its toll on grapes without directly destroying them. Wildfires and warmer temperatures can transform the flavor of wine, whose quality and very identity depends on the delicate chemistry of grapes and the conditions they’re grown in. Many growers and winemakers are increasingly concerned that climate change is robbing wines of their defining flavors, even spoiling vintages entirely. 

“That’s the big worry,” says Karen MacNeil, a wine expert living in Napa Valley and author of The Wine Bible. “That’s the heartbeat of wine — it’s connected to its place.” 

The greatest challenge that climate change brings to winemaking is unpredictability, MacNeil says. Producers used to know which varieties to grow, how to grow them, when to harvest the berries and how to ferment them to produce a consistent, quality wine — but today, every step is up in the air. This growing recognition is spurring researchers and winemakers to find ways to preserve beloved grape varieties and their unique qualities under the shifting and capricious conditions of today’s warming world. 

To learn about the threats to our favorite beverage, we spoke with wine experts from two renowned wine regions — Bordeaux in France and California — to understand how climate change is uprooting their traditional vines and wines, and traveled to the University of California, Davis, and nearby Napa Valley in late 2021 to speak with scientists, growers and winemakers.

We were treated to an inside look at how every stage of winemaking is transforming to preserve desired flavors and aromas — and yes, got to taste a lot of wine, from the finest Cabernet Sauvignon to samples spoiled by smoke and scorching heat.

Read the rest of the story, co-reported with Ula Chrobak, in Knowable Magazine and The Atlantic.

Sapiens: The last wild lions of Europe

Image: Nancy Thomas

Once upon a time, people near the valley of Nemea in southern Greece lived in mortal fear of a lion lurking in the surrounding hills and preying on the populace. Only mighty Hercules, challenged by the king of nearby Tiryns, could slay the beast.

The son of Zeus cornered the powerful carnivore in a cave and choked it to death with his bare arms. Thereafter, the people lived in peace, and Hercules continued his famed adventures.

Of course, the Nemean lion story is a mere fable, part of an eclectic cast of gods, heroes, and fantastic beasts that populated the myths of antiquity. There are certainly no wild lions in Europe today.

But early 20th-century archaeologists in mainland Greece thought that there might be some truth to the existence of lions in the region in ancient times. Why else do these creatures feature so prominently—and realistically—in art from the late Bronze Age, as well as myths and actual reports by later scholars from the Classical period, such as Aristotle and Herodotus?

Though such theories were long dismissed by other researchers, in 1978, two prominent German zooarchaeologists made a startling discovery. During an excavation of Tiryns—the same city whose legendary king dared Hercules into action—they chanced upon a feline heel bone near a human skeleton. It was unmistakably from a lion, they concluded, and possibly of the same species that inhabits parts of the African continent today.

The bone was only the first of dozens to surface in Tiryns and elsewhere over the following decades. Though some details remain unclear, many archaeologists and historians now use this evidence to conclude that modern lions once lived alongside people in parts of what is today Europe, including Greece, for hundreds of years. Today lion bones offer a rare glimpse into the Bronze Age world and the fraught relationship humans had with these fierce predators, animals that inspired legends and creative works for centuries.

“Now it’s possible to say that some [lion images] could have been recalled from real experiences on the [Greek] mainland,” says art historian Nancy Thomas. The finds, she adds, cast “a whole different light on the art … and how hunting real lions could have played into the elite structure development that was going on in Greece at the time.”

Keep reading in Sapiens

Knowable Magazine: What the World Can Learn From Britain’s Humble Hedge

Image: WelshDave, Wikimedia Commons

Hedgerows are as British as fish and chips. Without these walls of woody plants cross-stitching the countryside into a harmonious quilt of pastures and crop fields, the landscape wouldn’t be the same. Over the centuries, numerous hedges were planted to keep in grazing livestock, and some of today’s are as historic as many old churches, dating back as far as 800 years. Today, Britain boasts about 700,000 kilometers (435,000 miles) of them, a length that surpasses that of its roads.

In recent years, ecologists — especially in Britain, Ireland and continental Europe, but also in places that have more recently adopted hedgerows, such as California — have come to view these man-made structures as important ecosystems in their own right. They form a vital reservoir of biodiversity in human-dominated landscapes where many species might otherwise struggle to survive. By nurturing pollinating insects, they can enhance the yield of crops. And they do it all while pulling carbon out of the atmosphere.

This growing ecological appreciation is invigorating efforts in many regions to expand hedgerows, or hedges, and so help combat both the biodiversity and climate crises. More hedgerows, ecologists and policymakers hope, could provide a mutually beneficial way for farming to coexist with nature.

“Most people just drive or walk past hedgerows and maybe don’t think about them very much,” says Jo Staley, an ecologist at the UK Centre for Ecology and Hydrology, a nonprofit research institute. “But when you start to learn a bit about them, you see the potential.”

Read the whole story at Knowable Magazine

Scientific American: People May Have Used Fire to Clear Forests More Than 80,000 Years Ago

Image: Abu Shawka, Wikimedia Commons

New research suggests that early modern humans used fire to transform a dense, closed-canopy “Afromontane” forest (depicted above) into a bushy, open-canopy “miombo” woodland around northern Lake Malawi in Africa.

Humanity’s environmental impact did not start with the bang of agriculture or industrialization but a whisper initiated long ago—one that scientists are finally learning to hear.

New archaeological and paleoenvironmental findings now date human activity that transformed our natural surroundings to more than 80,000 years ago, after early modern humans settled on the northern shores of Lake Malawi at the lower tip of eastern Africa’s Great Rift Valley. These humans dramatically modified the landscape and ecosystem by burning forests to yield a sprawling bushland that remains today, according to a report published on May 5th 2021 in Science Advances.

The finding marks the oldest evidence yet of humans profoundly changing their environment with fire. And it could represent the earliest known case of people deliberately doing so, the researchers hypothesize.

Read the whole story in Scientific American

BBC Future: The human right that benefits nature

The history behind one of Costa Rica’s most important environmental commitments reads something like a legal fairytale. It started nearly 30 years ago, with a young boy who wanted to stop the pollution in his neighborhood and ended with a constitutional reform. The impacts of the boy’s efforts are still causing ripples to the present day.

It began in 1992, by a stream weaving through a small town near the capital, San José. Without a proper waste management system, locals would throw their garbage into the stream, causing waste to pile up at its banks. Frustrated about the situation, then 10-year-old Carlos Roberto Mejía Chacón, with help from his family, filed an appeal with Costa Rica’s constitutional chamber against the local municipality. Allowing the river to be used as a garbage dump, he argued, violated the human right to life, which requires adequate living conditions and protected, clean waterways.

The chamber sided with Chacón a year later and ordered the municipality to clear up the garbage and start managing residents’ waste properly. But it also came to a much deeper recognition. A clean and healthy environment is a very basis of human life, as are balanced ecosystems, biodiversity, and other elements of nature on which people depend, the judges reasoned. Just like food, work, housing and education, an all-round healthy environment should be considered a human right.

This remarkable conclusion not only set a new legal standard for courts around the country, but also spurred the decision to carve the human right to a healthy environment into Costa Rica’s legal DNA during a constitutional reform in 1994, recalls lawyer Patricia Madrigal Cordero, who was involved in the legislative process at the time. Since then, the constitutional right has helped guide many of Costa Rica’s widely praised – although far from perfect – environmental policies and reverberated through the country’s landscape and culture. “I think Costa Rica would be different if we didn’t establish that relationship between human rights and the environment,” Cordero says. 

The human right to a healthy environment – encompassing clean and balanced ecosystems, rich biodiversity and a stable climate – recognises that nature is a keystone of a dignified human existence, in line with a wealth of scientific evidence linking human welfare and the natural worldPeople depend on thriving ecosystems that clean water and airyield seafood and pollinators, and soak up greenhouse gases. Recognising this link legally can greatly strengthen human rights.

But equally important, Cordero notes, is that the right provides a powerful basis to protect nature itself. In a worsening global environmental crisis, some legal scholars have argued that the right to a healthy environment acts as a crucial legal pathway to protecting the natural world, both by encouraging governments to pass stronger environmental laws and allowing courts to hold violators accountable. Especially when installed into constitutions, such rights are taken seriously by many judicial systems and become hard to undo, creating an enduring force counteracting the interests against protecting nature.  

But although there is clear scientific consensus on the benefits of nature to people, the evolution of nature as a human right has been remarkably patchy around the world. Today, many Latin American countries are forging ahead while Europe and North America lag somewhat behind. Since the right’s first mention in the Stockholm Declaration in 1972 – a result of the first major environmental conference – some 110 countries have constitutionally recognised it. While its impact varies across the globe, it has created a powerful bulwark against a rising tide of environmental destruction in many countries, such as Costa Rica, Colombia and South Africa, as more nations look set to follow suit soon.

Of course, recognising the right “is not a magic wand we can use to solve all of our challenges”, says environmental lawyer David Boyd, who is appointed as a special rapporteur on human rights and the environment at the United Nations. “It’s a catalyst for better actions.”

Read the whole feature at BBC Future

The Counter: The pandemic could change U.S. fisheries forever. Will it be for better or for worse?

Image: Tom Santaguida

Not unlike its effect on humans, the pandemic’s impact on the seafood industry has been variable, erratic, often devastating. The first symptoms appeared long before Covid-19 gained a stronghold on U.S. shores, as China went into its first lockdown and a critical export market disappeared overnight—seafood processors and dealers in Maine saw international demand for lobsters temporarily vanish. Then as social distancing rules kicked in here, another major organ of the U.S. supply chain—restaurants, where most seafood purchases are made—fell limp. Then Covid outbreaks at processing plants caused the system to further buckle, leaving many fishermen with nowhere to sell their catch. Prices for many species plummeted. Some fishers gave up for the season, leaving boats tied up at the docks. 

“It wasn’t worth it,” recalled Brian Pearce, a commercial fisherman based in Portland, Maine, who catches pollock, hake, and cod, and has barely fished since the pandemic started. “The price was to the point where you’re not going to make enough money.”

To many in the food industry, the pandemic’s impact has exposed the fundamental vulnerabilities of a system that has long favored efficiency over resilience.  Like supply chains that draw products from many sources but are ultimately contingent on single outlets (e.g., export markets or restaurants). Or the fact that the majority of U.S.-caught seafood is exported to other countries, but—paradoxically—most seafood Americans eat is imported. 

But the sledgehammer of 2020 also demonstrates what can make food systems more resilient to crises. Remarkably, consumers are experiencing a newfound appetite for locally caught, sustainable seafood. And accordingly, a slice of the U.S. fishing industry has fattened slightly this year: small, locally operated fisheries which have built their own supply chains to serve consumers, often delivering directly to their door. No strangers to challenges or disaster, many individual fishermen have also pivoted towards selling directly to the public—with mixed success. Yet what these lessons mean for the future of the industry—and if they’re enough to create resilient fisheries that can weather future storms—remains an open question.

Read the full story at The Counter

BBC Future: How unseasonal winters affect our minds

Image: BBC/Javier Hirschfeld/Getty Images

When my family moved some 20 years ago from rainy London to the German countryside, I was thrilled to live in a place with what I considered a “proper winter”. In January or February, the snow would usually stay with us for a few weeks – sometimes knee-deep and liberating me from school. I’d go sledging, build igloo-like caves, or join my parents throwing snowballs for our dogs and – perhaps unfairly – laugh at their hopeless quests to retrieve them from mounds of snow. But over time, those spectacular winters turned into a mundane drizzle. In recent years, my parents – with whom I usually spend the winter – have rarely seen an inch of snow, and if they did, it quickly turned into slush.

I’m privileged to be distant from the most dramatic effects of climate change, like forest infernos or devastating hurricanes. Yet the silent transformation of winter’s character can also weigh on one’s psyche. To me, it’s more than just a reminder of the wrenching planetary change we’ve caused and the hopelessness and anger I associate with it. There is something unique to witnessing the deterioration of this season. Some Nordic countries have words that come close to this feeling, like the Finnish “lumiahdistus”, describing an anxiety related to desiring snow or not knowing whether it will come. In English, we might sum it up as “winter grief”.

Read my essay for BBC Future about how the loss of true winters is affecting our traditions, culture, and identity.

The Scientist: Can Rewilding Large Predators Regenerate Ecosystems?

Image: Matias Rebak

In the absence of firm evidence, conservationists have been eager to interpret early predator reintroduction studies—largely based on the purported regenerative ecological effects of returning gray wolves (Canis lupus) to Yellowstone National Park in the mid-1990s—as a rationale for bringing predators back to many parts of the globe. In Colorado, for instance, conservation organizations have been using such findings to push for the approval of a bill on the November ballot that would effectively mandate wolf reintroduction in the state to restore the ecosystem’s “natural balance.” But some ecologists caution that the ecological outcomes of such projects are unclear. 

In search of answers, scientists are employing novel approaches to study the ecological roles of large carnivores, from the African savannah and the Andean plateau to the ocean, and to understand how ecosystems change as they are lost or reintroduced. What they’re finding is that predators have powerful, yet nuanced and complex effects that ripple through food webs in what are known as trophic cascades—effects that depend not only on the nature of the hunter itself, but also on characteristics of its prey and the habitat the animals share. 

“There’s still good reason to believe that trophic cascades will . . . occur in many systems,” Smith says. “It’s just that we don’t really have all the data yet to understand exactly when, where, and why.”

Read the full story at The Scientist