It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, October 05, 2020
The world's southernmost tree grows in one of the windiest places on Earth, but climate change is shifting those winds
The world's southernmost tree grows in one of the windiest places on Earth – but climate change is shifting those winds
On Isla Hornos, Magellan’s beech trees grow in wind-protected nooks and crannies. Credit: Andres Holz, CC BY-ND
In 2019, my research team and I found the world's southernmost tree on an island at the edge of South America. The diminutive tree is 42 years old, stretches several meters along the ground but is only half a meter, or about a foot and a half, tall. In some other place, this tree would grow tall and upright, but here, incredible winds warp and constrain the tree both in height and in where it grows. And due to climate change, those winds are changing.
Standing on the southern side of that wind-battered tree means all trees in the world are to your north, with nothing behind you but some grasses, ocean and Antarctica. Isla Hornos, also known as Cape Horn, supports a small population of Nothofagus betuloides – the Magellan's beech or coigüe. Wind is omnipresent. Cape Horn is one of the windiest places on the planet, and during the expedition, our team faced hurricane-force winds of 75 mph for days at a time.
This wind appears to be the main constraint for arboreal life on the island—trees are found only in sheltered locations behind cliffs and hills. While the area hasn't warmed dramatically, climate change is intensifying the westerly winds that rake the region. Evidence from the nearby Falkland Islands also indicates that the wind direction is shifting too. Because of this, forests on Cape Horn that were previously growing in sheltered areas are now exposed to wind. We found long stretches of dead trees along the edges of the small forests, suggesting that shifting winds caused by climate change may be killing off trees even as new sheltered areas emerge.
Credit: The Conversation
Species must either migrate, adapt or die in response to climate change. By monitoring the geographic edges of where a species lives—like the southernmost tree our team found—scientists can get a handle on the migration ability of various species. This is important for prioritizing conservation plans or when considering more extreme measures, like assisted migration, to help species keep pace with climate change.
Wind has received relatively little attention in regards to setting the limits of species, but it is quite important on mountains, oceanic islands and, as we now know, the overall global extent of trees. Changes in temperature and precipitation are often discussed as worries on a changing planet, but in places like Isla Hornos, climate change's effect on wind matters just as much.
Additionally, this area is relatively pristine—we didn't find a single invasive species, and there has been little human presence in the island, ever. As the climate changes, documenting this location so that scientists can know what is there and how it is changing is critical for future conservation.
Isla Hornos is remote, inhospitable and nearly untouched by humanity. Credit: Brian Buma, CC BY-ND
IslaThe researchers stand tall over the shrunken tree in the foreground during a rare break from the relentless, often hurricane-force winds. Credit: Andres Holz, CC BY-ND
Researchers still know relatively little about the southernmost forests of the world. While there is evidence that the winds have changed, the specific cause of death for forests can be determined only with long-term research.
Further, there are only short climatic records from the island. Even basic information—like the length of the growing season—is still unknown. Repeat studies will need to be done if scientists really want to learn how life is changing in this remote but globally significant locale.
Revisiting this landscape to set up long-term research is important given the unique nature of this global signpost—the world's southernmost tree. More than that, however, I hope this expedition can rally people to study range edges around their own homes.
Together with National Geographic, ESRI and iNaturalist, on Sept. 26, I launched an interactive exploration challenge called The Edges of (All) Life exploration project. Anybody can look up the edges of species ranges in their own neighborhood and go searching for an individual that will push those boundaries out farther. I may have found the world's southernmost tree, but you could find the northernmost dogwood, the northernmost Douglas fir or the southernmost maidenhair fern. No matter where you live, there is likely a unique edge nearby, and finding these ranges is critically important for the conservation of that particular species.
What exactly is the relationship between soil nitrogen, corn yield, and nitrogen loss? Most farmers would be forgiven for assuming a straightforward linear relationship: more nitrogen, more grain yield, and maybe, more loss. That's the assumption many nitrogen management models are based on, but it turns out there's very little published science to back up that assumption.
In a recent paper leveraging a multi-year dataset from 11 experimental plots and on-farm trials around the state, University of Illinois scientists definitively established the relationship between soil nitrogen at different growth stages and corn yield. The results provide more precise ways to manage nitrogen for grain yield while lowering nitrogen losses.
"Technology nowadays moves very fast. There's a lot of modeling tools out there to help growers match nitrogen to crop needs, but very little published data showing the relationship," says Giovani Preza-Fontes, doctoral researcher in the Department of Crop Sciences at Illinois and lead author on the paper. "Our work shows soil nitrogen explains the majority (46-61%) of the variation in grain yield. It is a good predictor."
This information could complement crop modeling efforts, but it should also help farmers feel more confident in their nitrogen management decisions at critical moments.
"When we get a lot of rain, people often guess that some nitrogen was lost from the soil, and may be inclined to put more on. We did this study to try to show how much the crop needs to have in the soil at different stages of growth," says Emerson Nafziger, emeritus professor in crop sciences and co-author on the study.
Researchers applied nitrogen at different rates, times, and forms, then measured the amount of soil mineral nitrogen (SMN) to see how much nitrogen was available to the plant over time. They measured SMN several times during the first half of the growing season, beginning when corn was about a foot tall and ending as the crop approached pollination.
Interestingly, they found the amount of SMN needed to maximize grain yield changed over time as the crop developed.
"In early June, with plants about a foot tall, we found that corn needed more nitrogen in the soil than it needed later. Ten to 14 days later, the SMN level needed for best yields had dropped by about one-third, and it stayed at that level for two more sampling periods, into early July. That's probably our most surprising finding," Nafziger says. "It's some of the first data that's been published on how soil nitrogen actually changes."
"We know the plant's taking up its nitrogen most rapidly during that period, and the fact that soil nitrogen isn't changing very much shows that the nitrogen is coming from soil organic matter through the process of mineralization. Mineralization is a microbial process favored by the same conditions that favor rapid crop growth, so it's at its maximum rate during this period," he adds.
In other words, adding more nitrogen during rapid growth may end up causing an excess of soil nitrogen that could lead to losses.
To better estimate potential losses, the researchers calculated a simple nitrogen balance (input as nitrogen fertilizer minus output, removed in grain) for each site and year.
"We confirmed there's a tradeoff between productivity and environmental impact. We found a 22% yield increase when SMN increased from deficient to optimal levels, but adding enough nitrogen also increased the probability of environmental nitrogen losses," Preza-Fontes says. "It's important to not only focus on increasing productivity when developing new tools for nitrogen management. We also need to account for potential nitrogen losses to meet sustainability goals in the region."
The article, "Relationship of in-season soil nitrogen concentration with corn yield and potential nitrogen losses," is published in the Soil Science Society of America Journal.
A brutal war and rivers poisoned with every rainfall: How one mine destroyed an island
This week, 156 people from the Autonomous Region of Bougainville, in Papua New Guinea, petitioned the Australian government to investigate Rio Tinto over a copper mine that devastated their homeland.
Locals living downstream of the abandoned mine pan for gold in mine waste. Credit: Matthew Allen, Author provided In 1988, disputes around the notorious Panguna mine sparked a lengthy civil war in Bougainville, leading to the deaths of up to 20,000 people. The war is long over and the mine has been closed for 30 years, but its brutal legacy continues. When I conducted research in Bougainville in 2015, I estimated the deposit of the mine's waste rock (tailings) downstream from the mine to be at least a kilometer wide at its greatest point. Local residents informed me it was tens of meters deep in places.
I spent several nights in a large two-story house built entirely from a single tree dragged out of the tailings—dragged upright, with a tractor. Every new rainfall brought more tailings downstream and changed the course of the waterways, making life especially challenging for the hundreds of people who eke out a precarious existence panning the tailings for remnants of gold.
The petition has brought the plight of these communities back into the media, but calls for Rio Tinto to clean up its mess have been made for decades. Let's examine what led to the ongoing crisis. Triggering a civil war
The Panguna mine was developed in the 1960s, when PNG was still an Australian colony, and operated between 1972 and 1989. It was, at the time, one of the world's largest copper and gold mines.
It was operated by Bougainville Copper Limited, a subsidiary of what is now Rio Tinto, until 2016 when Rio handed its shares to the governments of Bougainville and PNG.
When a large-scale mining project reaches the end of its commercial life, a comprehensive mine closure and rehabilitation plan is usually put in place.
But Bougainville Copper simply abandoned the site in the face of a landowner rebellion. This was largely triggered by the mine's environmental and social impacts, including disputes over the sharing of its economic benefits and the impacts of those benefits on predominantly cashless societies.
Following PNG security forces' heavy-handed intervention—allegedly under strong political pressure from Bougainville Copper—the rebellion quickly escalated into a full-blown separatist conflict that eventually engulfed all parts of the province.
By the time the hostilities ended in 1997, thousands of Bougainvilleans had lost their lives, including from an air and sea blockade the PNG military had imposed, which prevented essential medical supplies reaching the island. The mine's gigantic footprint
The Panguna mine's footprint was gigantic, stretching across the full breadth of the central part of the island.
The disposal of hundreds of millions of tons of tailings into the Kawerong-Jaba river system created enormous problems.
Rivers and streams became filled with silt and significantly widened. Water flows were blocked in many places, creating large areas of swampland and disrupting the livelihoods of hundreds of people in communities downstream of the mine. These communities used the rivers for drinking water and the adjacent lands for subsistence food gardening.
Several villages had to be relocated to make way for the mining operations, with around 200 households resettled between 1969 and 1989.
In the absence of any sort of mine closure or "mothballing" arrangements, the environmental and socio-economic impacts of the Panguna mine have only been compounded.
Since the end of mining activities 30 years ago, tailings have continued to move down the rivers and the waterways have never been treated for suspected chemical contamination. Long-suffering communities
The 156 complainants live in communities around and downstream of the mine. Many are from the long-suffering village of Dapera.
In 1975, the people of Dapera were relocated to make way for mining activities. Today, it's in the immediate vicinity of the abandoned mine pit. As one woman from Dapera told me in 2015: "I have traveled all over Bougainville, and I can say that they [in Dapera] are the poorest of the poor."
The complainants say by not ensuring its operations didn't infringe on the local people's human rights, Rio Tinto breached OECD guidelines for multinational enterprises.
The Conversation contacted Rio Tinto for comment. A spokesperson said: "We believe the 2016 arrangement provided a platform for the Autonomous Bougainville Government (ABG) and PNG to work together on future options for the resource with all stakeholders."
While it is our belief that from 1990 to 2016 no Rio Tinto personnel had access to the mine site due to on-going security concerns, we are aware of the deterioration of mining infrastructure at the site and surrounding areas, and claims of resulting adverse environmental and social, including human rights, impacts.
We are ready to enter into discussions with the communities that have filed the complaint, along with other relevant parties such as BCL and the governments of ABG and PNG.
A long time coming
This week's petition comes after a long succession of calls for Rio Tinto to be held to account for the Panguna mine's legacies and the resulting conflict.
A recent example is when, after Rio Tinto divested from Bougainville Copper in 2016, former Bougainville President John Momis said Rio must take full responsibility for an environmental clean-up.
And in an unsuccessful class action, launched by Bougainvilleans in the United States in 2000, Rio was accused of collaborating with the PNG state to commit human rights abuses during the conflict and was also sued for environmental damages. The case ultimately foundered on jurisdictional grounds. Taking social responsibility
This highlights the enormous challenges in seeking redress from mining companies for their operations in foreign jurisdictions, and, in this case, for "historical" impacts.
The colonial-era approach to mining when Panguna was developed in the 1960s stands in stark contrast to the corporate social responsibility paradigm supposedly governing the global mining industry today.
Indeed, Panguna—along with the socially and environmentally disastrous Ok Tedi mine in the western highlands of PNG—are widely credited with forcing the industry to reassess its "social license to operate."
It's clear the time has come for Rio to finally take responsibility for cleaning up the mess on Bougainville.
With the city of Louisville still reeling from a grand jury's recent findings about Breonna Taylor's shooting, the ongoing debate about the limits of excessive force continues to divide the nation. But unlike in the past, when such stories were often quickly forgotten, the pervasive role of citizen video evidence and subsequent coverage by the press has transformed the public response.
"These tragic events are having an impact on the broader public," said Kevin Mullinix, assistant professor of political science at the University of Kansas. "Many people aren't just reading about them and moving on with their day. We're finding it's actually changing people's beliefs."
His new article, "The Feedback Effects of Controversial Police Use of Force," appears in the September edition of Political Behavior.
Co-written by Toby Bolsen, Georgia State University, and Robert Norris, George Mason University, the article finds that such actions against minority civilians increase support for body cameras, influence beliefs about excessive force and alter attitudes toward law enforcement.
Mullinix's team studied nearly 3,000 participants who were randomly assigned to receive (or not receive) a text-based news article, video or both involving a real-world case of police harming a minority civilian. One of these resulted in a non-lethal injury and the other in a death.
"You can find people who seemingly have complete confidence in police, but seeing these stories gets them to think, 'Maybe we do need body cameras,'" he said.
Mullinix, an expert in public opinion and public policy, was most surprised by how viewers reacted to the news articles compared to the videos.
"The text-based stories proved almost as powerful as the videos in a lot of circumstances," he said.
"Certainly, we observed stronger emotional responses to the videos. Reading a story might not make you quite as angry as watching the George Floyd video—you can't help but have an emotional reaction when you see that. But the text-based stories proved almost as powerful as the videos in shifting attitudes toward police. This suggests that even text-based journalism can still be pretty potent."
Mullinix became interested in researching this topic after discussions arose with his students about the choking death of Eric Garner ("I can't breathe") and shooting of Walter Scott, an unarmed black man in South Carolina whose death was disputed when a video later surfaced contradicting the official police report.
"I talked about them in my classes, but I hadn't considered studying what their effects were for a few years," Mullinix said. "The most powerful for me was the Walter Scott tragedy. It was horrifying. It brought me to tears."
The professor explains the Taylor case specifically fits in with his research involving the consequences of a police killing.
"We find that reading news stories or watching the videos focused on police use of force lowers people's confidence that officers will receive the appropriate consequences. When there aren't criminal charges filed, I would only expect these types of beliefs to become even stronger," he said.
Mullinix notes that his team didn't undertake this research to destroy trust in law enforcement. Rather, he's hoping to understand the overall effects the events have on American society.
He also presumes the police want to see the results of his research.
"A lot of law enforcement are interested in these kinds of findings because they've been worried about a crisis of legitimacy for years," he said. "They know these stories are out there, and they're worried what they're doing for the public sentiment. What we're finding here substantiates their concerns."
This work piggybacks off Mullinix's previous studies focusing on wrongful convictions and racial disparities in the justice system and traffic stops.
"Across all of my research, I'm constantly trying to understand what types of information and communication impact people's attitudes and support for policy reform," he said. "This fits into my broader research of trying to figure out when persuasion does and does not occur."
While unjustified police shootings and subsequent protests to them are unlikely to be solved overnight, Mullinix hopes these tragedies prove a catalyst for evidence-based policy reform and legitimate change.
"This should definitely raise a serious discussion about policing. We should not just dismiss such events as outliers," he said. "Hopefully, it prompts real discussions about what kind of reforms we can implement to make sure these types of things don't happen anymore."
For many people, the word "folklore" is synonymous with the past: beliefs at odds with contemporary society; myth and legend, even magic.
It is true that folklore helps us learn about our ancestors and their lives. As we continue to mark Armistice Day with a two-minute silence, we understand the momentousness of the end of the first world war. In some parts of England, the restoration of the monarchy in 1660 is still celebrated as Oak Apple Day.
But it's not all about the past. In response to Taylor Swift's new album (also entitled "folklore"), the American Folklore Society created a resource to demonstrate just how contemporary folklore is. It says that, despite its dusty connotations, folklore is the knowledge of the people "displayed through expressive culture."
I have been tracking how people are expressing beliefs and values using folkloric practices today. It seems that during these dark times they are being used to visibly brighten our communities. Many of us will have perpetuated these customs simply for something to do—particularly families desperate for ideas to occupy children.
So here are five folkloric customs that could come to define this age in the future. 1. Window displays
Writing in the latest newsletter from The Folklore Society, lecturer in history and folklore, Ceri Houlbrook observed that "ritual deposits are placed in private spaces but for public consumption, and symbols are adopted, such as the rainbow, to express hope and support." For many of us, spotting window displays during our limited exercise became a rite in itself.
The rainbow has long been used as a symbol of hope and unity. The child-created window displays are thought to have originated in Italy – the first European country to experience tough lockdown measures. Accompanied by messages of gratitude towards the NHS, these displays demonstrated children's ability to contribute to the wider pandemic conversation.
2. Scarecrows
Community scarecrow festivals are common in the UK and the idea was borrowed for domestic lockdown displays. Photographer of British folklore, Sara Hannant, says scarecrows are "guardians of the harvest."
In lockdown, the scarecrow was often seen dressed up as a key worker in tribute. But their position is not always positive and they can sometimes frighten humans as well as birds. Some of the scarier scarecrows seen during lockdown were, in fact, effigies created to pillory politicians.
3. Painted pebbles, stone snakes
Another pre-COVID custom, the hiding and seeking of painted pebbles to amuse children and to forge connections in the community, also became an integral part of community folklore. Passing on knowledge—anonymously and creatively—was made possible through messages of reassurance painted on pebbles and displayed outside homes, at community focal points or hidden for others to find.
Stones have long had pandemic connotations. The "Boundary Stone" for example was where isolated villagers in Eyam, Derbyshire, left money and received food during the 1665 plague.
During lockdown, pebble painters also created stone snakes. Some were created organically by leaving pebbles in a line to encourage others to add theirs. But others were more organized, such as the long "COVID snake" created at Pavilion Gardens in Buxton, Derbyshire. 4. Kerbside gifts
Painted pebbles were not the only lockdown gifts. With more time at home and in the neighborhood, residents took the opportunity to weed out unwanted belongings and, with charity shops and recycling centers closed, left freebies for passers-by. Some made the clear-out more appealing and fun. In one street in Nottingham (pictured above) a resident wrapped up the books, CDs and DVDs she was giving away to treat her neighbors to a lucky dip.
Small tokens or notes of inspiration were also left as inspiring gifts for passers-by in some parts of the UK. For example, in Mapperley, Nottingham, quotes were pinned to trees in an attempt to spread positivity. These displays supplied crowd-sourced distractions while providing reassurance and solidarity for both purveyor and reader.
5. Doorstep noise
The Guardian deemed Clap for Carers the "unBritish ritual" due to its loud, proud demonstration being uncharacteristic for famously reserved Brits. But for 10 weeks, 8pm on Thursdays was a raucous affair with people applauding keyworkers on their doorsteps. In some neighborhoods, this was augmented by fireworks, car horns, pots and pans and—in some cases—a prompt for socially distanced community celebration.
Residents of Belper, Derbyshire, took the noise-making further, turning out at 6.30pm each lockdown evening to moo for two minutes. Begun by Jasper Ward to "fight lockdown loneliness and boredom," the moo has been replicated across the world. Like Clap for Carers, there are plans for an annual commemoration beginning in 2021. Weekly doorstep racket-making, it seemed, became a cathartic method to remind ourselves of the people beyond our four walls.
As lockdown curtailed social interactions, these COVID customs enabled people to make connections and demonstrate meaning. A rainbow in a window can be both a child's delightful creation and a signal of hope. Participation in Clap for Carers a statement of solidarity and a simple acknowledgement of thanks.
Folklore researcher at the Elphinstone Institute, Nicolas Le Bigre, who is documenting COVID customs as part of "Lockdown Lore" says it is too early to say whether these communal acts will re-emerge in other periods of global crisis, or whether they will retire, becoming symbols of the time. But he added: "I can at least smile at the wealth of creativity that has come my way." And that has been a comfort to us all.
We discovered a missing gene fragment that's shedding new light on how males develop
October 2, 2020 by Peter Koopman
Credit: Shutterstock
It's one of the most important genes in biology: Sry, the gene that makes males male. Development of the sexes is a crucial step in sexual reproduction and is essential for the survival of almost all animal species.
Today in the journal Science, my international collaborators and I report the surprise discovery of an entirely new part of the Sry gene in mice—a part we had no idea existed.
I co-discovered Sry in 1990. It is the gene on the Y (male) chromosome that leads to the development of male characteristics in mice, humans and most other mammals. Since then, Sry has been the subject of intense study worldwide because of its fundamental role in mammalian biology.
We have come to understand, in some detail, how Sry acts to trigger a cascade of gene activity that results in the formation of testes, instead of ovaries, in the embryo. Testes then stimulate the formation of other male characteristics.
But it's clear we don't have all the answers just yet. Our results published today take us one step further in the right direction.
Hidden in plain sight
For 30 years, we have understood the Sry gene is made up of one exon, a segment of a gene used to code for amino acids, the building blocks of proteins. This can be compared to a computer file consisting of one contiguous block of data on a hard disk.
Our newest research reveals there's actually a second exon in mouse Sry. This is like finding a whole new separate block of previously hidden data.
The mouse genome, like the human genome, has been extensively characterized due to the availability of advanced DNA sequencing and related technologies. Researchers commonly assume all the genes and all the parts of the genes have already been discovered.
But earlier this year, scientists in Japan uncovered what looked like a new piece of the Sry gene in mice. New sequencing approaches revealed what appeared to be two versions of Sry: a short, single-exon form and a longer, two-exon form. They called this two-exon version "Sry-T."
They collaborated with my group at the University of Queensland and removed the new exon using CRISPR, a gene editing tool that lets researchers alter DNA precisely. Together we discovered this prevented Sry from functioning: XY mice (which would normally develop as males) developed as females instead.
Conversely, adding Sry-T to fertilized XX mouse eggs (which would normally develop as females) resulted in males.
On the left, an XY mouse lacking Sry-T that developed as female. On the right, an XX mouse carrying the Sry-T gene that developed as male. Credit: Makoto Tachibana, Osaka University, Author provided
Implications for human sex determination
Importantly, although human Sry does not have the added exon, our discovery may reveal new functions that might be shared between mouse and human Sry.
The DNA sequence of the new exon in Sry-T may point us towards discovering some of the genes and proteins that interact with Sry, something that has been elusive up till now.
And interactions we find in mice may also occur in humans. Studying what human Sry interacts with may help explain some cases of differences in human sex development, otherwise known as "intersex" development. This is a common but poorly understood group of mostly genetic conditions that arise in humans.
Currently, we don't know the genetics behind a large proportion of intersex conditions. This is partly because we don't yet know all the genes involved in the human sex development pathway.
Towards a better understanding of male sex development
Scientifically, this discovery is a bit like discovering a new cell type in the body, or a new asteroid in the Kuiper belt. As with many scientific discoveries, it challenges what we thought we knew and raises many questions.
What is the function of the new exon in Sry-T?
Currently, we only have part of the answer. It turns out the first exon of Sry, the one we already knew about, contains "instability sequences" at its end. These are sequences that cause proteins to fray and degrade.
An important function of the newly discovered second exon is to mask the instability sequences, seal the end of the Sry protein and prevent it from degrading. In other words, this second exon is crucial to the development of male babies.
What's more, this protection mechanism represents an unusual and intriguing evolutionary mechanism that has acted to help stop vulnerable Y-chromosome genes from literally falling apart.
But it's early days yet. The challenge now is to understand whether there are more functions hidden within the newly discovered exon.
If so, this information may provide some of the missing links that have stood in the way of our full understanding of how Sry works at a molecular level and of how males and females come to be.
More information: The mouse Sry locus harbors a cryptic exon that is essential for male sex determination, Science 02 Oct 2020: Vol. 370, Issue 6512, pp. 121-124
This article is republished from The Conversation under a Creative Commons license. Read the original article.This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about ScienceX Dialog and how to participate.
Ice discharge in the North Pacific set off series of climate events during last ice age
Living planktic foraminifera from the North Pacific. Credit: Jennifer Fehrenbacher, Oregon State University
Repeated catastrophic ice discharges from western North America into the North Pacific contributed to, and perhaps triggered, hemispheric-scale changes in the Earth's climate during the last ice age, new research published online today in Science reveals.
The discovery provides new insight into the impact rapidly melting ice flowing into the North Pacific may have on the climate across the planet, said Maureen Walczak, a paleoclimatologist in Oregon State University's College of Earth, Ocean, and Atmospheric Sciences and the study's lead author.
"Understanding how the ocean has interacted with glacial ice in the past helps us predict what could happen next," Walczak said.
The Cordilleran ice sheet once covered large portions of western North America from Alaska to Washington state and western Montana. Radiocarbon dating and analyses of the marine sediment record revealed that recurrent episodes of discharge from this ice sheet over the past 42,000 years were early events in a chain reaction of disturbances to the global climate. These disturbances triggered changes in deep ocean circulation and retreat of ice sheets in the North Atlantic.
The findings challenge theories that those massive, globally-reaching disturbances originated in the North Atlantic as rapid ice loss from the Laurentide ice sheet, another massive ice sheet that covered much of Canada and the northern United States, including the upper Midwest and Northeast. The Laurentide ice loss events are known as Heinrich Events.
"The outcome of this research was unexpected. The data irrevocably says that the Pacific ice goes first, with Heinrich Events and other changes following in a rhythm. The Pacific Ocean sets the drum beat," Walczak said. "This is a paradigm shift in our thinking about how these events are connected."
To gain insight into the climate history of the North Pacific, an international team of researchers collected and analyzed sediment cores from the northern Gulf of Alaska that were recovered by drilling as part of the International Ocean Discovery Program.
Epoxy sand grain mounts of iceberg rafted debris in sample 341_19E14H2W_100 in cross polarized light and plane light. Credit: Gina M. Carney (Appalachian State University)
"Getting these new insights took years of work. We first mapped the seafloor and recovered short sediment cores in 2004, drilled longer cores in 2013 and had 16 years of painstaking laboratory work involving several Ph.D. students," said Alan Mix, the project's principal investigator and co-author of the paper.
"This was a virtually unknown area when we started, and now it offers among the most detailed and best-dated long records of ocean change on the planet during the ice age," said Mix, a distinguished professor in OSU's College of Earth, Ocean, and Atmospheric Sciences.
Researchers measured radioactive isotopes of carbon using two particle accelerators to establish the chronology of events and also added meticulous counts of small rocks dropped by icebergs known as ice-rafted debris.
The research team traced the source of the ice-rafted debris back to purges of massive ice streams emanating from the Cordilleran ice sheet, which covered northern Washington, most of British Columbia and southern Alaska from about 70,000 to 17,000 years ago.
Dirty icebergs broke off from surging ice streams and drifted northward in ocean currents, carrying and eventually dropping their load of sand, pebbles and gravel, leaving a record of rapid ice retreat buried in the deep sea like sunken treasure.
The authors of the study named these Alaskan iceberg dumps "Siku Events" after the Inuit word for ice. The big surprise, discovered by combining the record of glacial debris with the radiocarbon chronology, was that Siku Events immediately preceded Heinrich events, which are a similar type of ice purge in the North Atlantic.
Scientists have been aware of Heinrich Events, from similar evidence of ice-rafted debris in the North Atlantic, for more than 30 years but the trigger for those events has never been convincingly explained, the researchers said.
Research vessel JOIDES Resolution in port in Victoria, British Columbia, prior to Integrated Ocean Drilling Program's Expedition 341, to investigate the Southern Alaska Continental Margin. Credit: A.L. Slagle
It makes sense for the Pacific Ocean to be involved in major planetary changes, Mix said. The Pacific Ocean is connected to the rest of the world by large-scale atmospheric circulation and physically around Antarctica, and during times of high sea level, through the Bering Strait and the Arctic Ocean to the North Atlantic.
"The Pacific Ocean is the largest exchangeable reservoir of heat and water and carbon dioxide on Earth, simply because of its massive size," he said. "It really is the 800-pound gorilla in the zoo of climate beasts."
Today the ice that remains along the coast of Alaska is mostly retreating and may be gone within this century as the climate warms. The melting ice will drain to the Pacific and the Arctic, contributing to sea level rise and impacting the balance of buoyant fresh and dense salty water in the ocean, much as it did in the past.
If the current ice melt follows patterns of the past, and happens quickly, it could contribute to the retreat of distant glacial systems in the North Atlantic and the Arctic.
"This is yet another reason that it is prudent to slow down warming by reducing our fossil-fuel use," Mix said.
"The new findings are likely to fuel increased interest in the North Pacific, an area that has not been as well-studied as other parts of the planet," Walczak said.
One thing that remains unclear is why the discharges from the Cordilleran ice sheet occurred. Researchers also would like to better understand the relationship between the discharges of the Cordilleran and the other climate events.
"Why did the other ice sheets respond to the retreat of the Cordilleran? How fast do the dominoes fall in this sequence of events?" Walczak asked. Those are among the questions the research team is continuing to investigate.
Egyptian goose (Alopochen aegyptiaca) originally from Africa and now established in Central and Western Europe. Credit: Professor Tim Blackburn, UCL
The number of alien (non-native) species, particularly insects, arthropods and birds, is expected to increase globally by 36% by the middle of this century, compared to 2005, finds new research by an international team involving UCL. Published in Global Change Biology, the study also predicts the arrival of around 2,500 new alien species in Europe, which translates to an increase of 64% for the continent over the 45-year period.
The research team led by the German Senckenberg Biodiversity and Climate Research Centre hope it should be possible to reduce this number with stricter biosecurity regulations.
Alien species are those that humans have moved around the world to places where they do not naturally occur. More than 35,000 such species had been recorded by 2005 (the date of the most recent comprehensive global catalogue). Some of these aliens can go on to become invasive, with damaging impacts to ecosystems and economies. Alien species are one of the main drivers of extinctions of animals and plants.
Co-author Professor Tim Blackburn (UCL Centre for Biodiversity & Environment Research and the Institute of Zoology, ZSL) said: "Our study predicts that alien species will continue to be added to ecosystems at high rates through the next few decades, which is concerning as this could contribute to harmful biodiversity change and extinction.
"But we are not helpless bystanders: with a concerted global effort to combat this, it should be possible to slow down or reverse this trend."
For the study, the research team developed a mathematical model to calculate for the first time how many more aliens would be expected by 2050, based on estimated sizes of source pools (the species that could end up becoming invasive) and dynamics of historical invasions, under a 'business-as-usual' scenario that assumes a continuation of current trends.
The model predicts a 36% increase in the number of alien plant and animal species worldwide by 2050, compared to 2005 levels.
Box tree moth, native to east Asia and now found across Europe. Credit: Professor Tim Blackburn, UCL
The study identifies high levels of variation between regions. The largest increase is expected in Europe, where the number of alien species will increase by 64% by the middle of the century. Additional alien hotspots are predicted to include temperate latitudes of Asia, North America, and South America. The lowest relative increase in alien species is expected in Australia.
Europe will also see the largest increase in absolute numbers of alien species, with around 2,500 new aliens predicted.
Lead author Dr. Hanno Seebens (Senckenberg Biodiversity and Climate Research Centre, Germany) said: "These will primarily include rather inconspicuous new arrivals such as insects, molluscs, and crustaceans. In contrast, there will be very few new alien mammal species such as the well-known raccoon."
Co-author Dr. Franz Essl (University of Vienna) added: "Increases are expected to be particularly large for insects and other arthropods, such as arachnids and crustaceans. We predict the number of aliens from these groups to increase in every region of the world by the middle of the century—by almost 120% in the temperate latitudes of Asia."
The study also predicts that the rate of arrival of alien species will continue to increase, at least in some animal groups. Globally, by 2050, alien arthropod and bird species in particular will arrive faster than before, compared to the period 1960—2005. In Europe, the rate of new alien arrivals is expected to increase for all plant and animal groups except mammals.
Neither a reversal nor even a slowdown in the spread of alien species is in sight, as global trade and transport are expected to increase in the coming decades, allowing many species to infiltrate new habitats as stowaways.
Dr. Seebens said: "We will not be able to entirely prevent the introduction of alien species, as this would mean severe restrictions in international trade.
"However, stricter regulations and their rigorous enforcement could greatly slow the flow of new species. The benefits of such measures have been shown in some parts of the world. Regulations are still comparatively lax in Europe, and so there is great potential here for new measures to curtail the arrival of new aliens."
Disease-spreading ticks keep marching north as weather stays warmer
by Robert Langreth, Bloomberg News
Credit: Pixabay/CC0 Public Domain
Ticks are among nature's most hardy survivors. They've been around for at least 100 million years and used to feast on dinosaur blood. Their bodies contain anti-freeze to help them survive cold weather and their two front legs have carbon dioxide and infrared sensors to help detect when a warm-blooded mammal is approaching. Tiny hairs on their legs increases friction and allows ticks to latch onto animals that brush by. And blacklegged ticks, which spread the most disease in the U.S., are notoriously un-picky eaters, happy to ingest the blood of numerous mammals and birds, making them perfect for spreading disease from one species to the next.
Blacklegged ticks and their counterparts abroad used to be confined to certain climates, especially milder and humid temperate zones such as coastal New England. Now, they're present in places farther north where they didn't use to appear.
Researchers in Sweden were astonished when, in the 1990s, they discovered ticks creeping up the Baltic Coast and into the sparsely populated Northland. The disease-ridden prehistoric creatures brought north new cases of Lyme disease and other ailments. By 2009, the critters had reached the edge of the Arctic Circle.
In the mountains of the Czech Republic, ticks are now present above 1,100 meters of elevation; prior to the 1980s they apparently hadn't been able to survive much above 700 meters. In the U.S., they have spread north and west from their strongholds in southern New England and Upper Midwest to the far northern reaches of Minnesota and northern New England.
And from there, they've just kept going. In eastern Canada, government researchers have found that ticks are encroaching north at a rate of up to 50 kilometers a year, bringing disease with them.
The relentless northward march is closely linked to mild winters and warming summers that gave ticks more opportunity to find hosts. Understanding ticks' migration and their concurrent climb to ever higher latitudes and altitudes has grown from a passing curiosity to an obsession for Richard Ostfeld, a 65-year-old disease ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York. He's immersed himself in the study of ticks for almost three decades—and has spent the last decade looking at how climate affects tick survival.
"We should all be very worried," says Ostfeld, about the long-term risks of tick-borne disease. "This is a growing public health threat that we need to get under control because the longer it is allowed to spread unabated, the harder it is to reign back in."
While broad correlation between ticks' spread and global warming is clear, predicting where they will go next as the climate changes is surprisingly daunting, as is proving cause and effect. Little is known about the precise details of what weather conditions kill ticks in the field, and, complicating matters, tick populations bounce up and down naturally for a plethora of reasons, such as the abundance of acorns that their rodent hosts feed on. Predicting where ticks will spread next, "is super important," says Ostfeld, "because where ticks go so too goes tick-borne illness."
In the U.S., those illnesses have more than doubled in recent years, to more than 47,000 cases in 2018 from 22,000 cases in 2004. Lyme Disease accounts for the bulk of this, but numerous lesser-known tick ailments are on the rise as well, including flu-like anaplasmosis and babesiosis, a malaria-like infection of red blood cells. Ticks can also transmit Powassan virus, the rare microbe that killed former North Carolina Senator Kay Hagan last year. The U.S. Centers for Disease Control and Prevention lists 16 bacterial, viral and protozoan diseases that are transmitted by ticks in the U.S. alone, with several more that are mainly present in other parts of the world. And more are being discovered all the time.
In the woods just beyond Ostfeld's office, a team of six researchers is conducting one of the first-ever rigorously controlled field experiments designed specifically to investigate ticks and climate change. They are artificially warming plots of soil and, over the next year, ticks are being placed at various life stages inside fabric bags to see at what temperatures and in which environments they are able to thrive and under which conditions they tend to start dying off. The number of variables is immense—everything from snow-cover, to relative humidity, to the activity of host mammals can affect tick survival.
The complexity of it all keeps Ostfeld up a night. But if this, and other experiments in North Carolina and two other locations in upstate New York succeed, it will provide some of the first reliable data that climate modelers can use to predict where tick-borne diseases are going to pop up in the future.
Ticks' reclusive lifestyle make them hard to study. They eat just three times in their lifespan of two years but spend as much 20% of their lives looking for meals. This process, called questing, involves standing on the edge of a leaf or blade of grass and sticking two hairy legs out ready to grab onto any mammal that happens to brush by. But most of the time, as far as researchers can tell, ticks spend their existence "doing pretty much nothing," says Ostfeld.
Perhaps a tick's most brilliant arsenal is how it renders its victim oblivious to its bite. When a tick sinks its pincerlike jaws and a barbed needle-like appendage called a hypostome into animal flesh, it releases a hospital-style drip of substances, including analgesics to stop the pain, antihistamines and anti-inflammatories to make sure it doesn't itch or swell, and anticoagulants to keep the blood flowing for days. The blacklegged tick, the primary disease-spreading tick species in the Northeast and Midwest, is especially good at undetected gorging.
Not so long ago, Lyme disease was rarely seen in Canada. Now, there are around 2,000 cases a year. Tick populations are "expanding northward all the time" in a pattern consistent with climate change being a driver, says Nicholas Ogden, a research scientist at the Public Health Agency of Canada. Longer warm seasons are giving ticks better chances to find hosts and complete their life cycle, he says "We are going to see more and more of Canada become suitable for ticks," he predicts.
While most research has focused on the blacklegged tick and its European relative, other species of ticks are also roaming into previously colder climes, including the so-called lone star tick, which is linked to red-meat allergy and can spread rare but potentially deadly Heartland virus as well as ehrlichiosis, a flu-like bacterial illness. Long thought of as a southeastern tick, it has made big inroads into Long Island and southern New England in recent years. In July, researchers at the University of Illinois found to their surprise that lone star ticks harboring the Heartland virus had inched north and become established within 60 miles of Chicago, according to research published in Emerging Infectious Diseases.
There's more to the spread of tick habitat and tick diseases than climate, of course. Forest fragmentation, growing deer populations, natural adaptation to colder climates, and ever-expanding suburbs all play a role, making the impact of climate change difficult to parse out. Some researchers argue the role of climate is overstated and that the northern spread is mostly explained by these other factors. "We have no idea what the changes in the weather might do to ticks," says Sam Telford, and epidemiologist and tick researcher at Tufts University. And warming could be neutral or good for some hard-hit regions now, if ticks are driven north out of population centers. "The data isn't really there."
That's where Ostfeld's work comes in. His field experiment on tick survival and climate change, designed with researchers at New York University and Washington State University, doesn't look like much at first glance. It sits in an unassuming patch of leafy woods a few yards behind the parking lot at the Cary Institute of Ecosystem Studies, 80 miles north of New York City. There, two patches of leaf-covered-soil, each roughly one square meter in size, have been divided into 90 squares like a big outdoor checkerboard. Thirty-eight of the squares are covered with tick-containing nylon fabric bags that extend down into soil cores scooped out with a golf hole cutting tool. Other squares contain a variety of temperature, relative humidity and soil moisture sensors that log the precise environmental conditions at all times.
The two patches are exquisitely designed to be essentially identical except for one thing: in one of the patches, the soil is heated with 110 evenly spaced heat probes in buried in the soil and connected to a 24-volt-solar powered battery. That will bring the temperature of the soil up by 2.5 degrees Celsius, about as much as this part of the country is expected to warm in the next 50 years.
"We know almost nothing about whether the ticks get killed outright by cold snaps in winter, hot spells in summer flooding events, or drought," says Ostfeld.
Even though ticks can't be eliminated, knowing where they are likely to spread diseases next could help public health authorities to alert local residents and doctors. Lyme disease is easily treatable with antibiotics if detected early, but if it's missed, the bacterium can spread throughout the body and cause complications ranging from arthritis to neurological complications. And this worst-case scenario is more likely to occur in locales that haven't experienced much Lyme disease or other tick-borne ailments.
"That is one of the consequences of climate change. It spreads in communities that have never experienced it before," Ostfeld says.
"Eat your spinach," is a common refrain from many people's childhoods. Spinach, the hearty, green vegetable chock full of nutrients, doesn't just provide energy in humans. It also has potential to help power fuel cells, according to a new paper by researchers in AU's Department of Chemistry. Spinach, when converted from its leafy, edible form into carbon nanosheets, acts as a catalyst for an oxygen reduction reaction in fuel cells and metal-air batteries.
An oxygen reduction reaction is one of two reactions in fuel cells and metal-air batteries and is usually the slower one that limits the energy output of these devices. Researchers have long known that certain carbon materials can catalyze the reaction. But those carbon-based catalysts don't always perform as good or better than the traditional platinum-based catalysts. The AU researchers wanted to find an inexpensive and less toxic preparation method for an efficient catalyst by using readily available natural resources. They tackled this challenge by using spinach.
"This work suggests that sustainable catalysts can be made for an oxygen reduction reaction from natural resources," said Prof. Shouzhong Zou, chemistry professor at AU and the paper's lead author. "The method we tested can produce highly active, carbon-based catalysts from spinach, which is a renewable biomass. In fact, we believe it outperforms commercial platinum catalysts in both activity and stability. The catalysts are potentially applicable in hydrogen fuel cells and metal-air batteries." Zou's former post-doctoral students Xiaojun Liu and Wenyue Li and undergraduate student Casey Culhane are the paper's co-authors.
Catalysts accelerate an oxygen reduction reaction to produce sufficient current and create energy. Among the practical applications for the research are fuel cells and metal-air batteries, which power electric vehicles and types of military gear. Researchers are making progress in the lab and in prototypes with catalysts derived from plants or plant products such as cattail grass or rice. Zou's work is the first demonstration using spinach as a material for preparing oxygen reduction reaction-catalysts. Spinach is a good candidate for this work because it survives in low temperatures, is abundant and easy to grow, and is rich in iron and nitrogen that are essential for this type of catalyst.
Zou and his students created and tested the catalysts, which are spinach-derived carbon nanosheets. Carbon nanosheets are like a piece of paper with the thickness on a nanometer scale, a thousand times thinner than a piece of human hair. To create the nanosheets, the researchers put the spinach through a multi-step process that included both low- and high-tech methods, including washing, juicing and freeze-drying the spinach, manually grinding it into a fine powder with a mortar and pestle, and "doping" the resulting carbon nanosheet with extra nitrogen to improve its performance. The measurements showed that the spinach-derived catalysts performed better than platinum-based catalysts that can be expensive and lose their potency over time.
The next step for the researchers is to put the catalysts from the lab simulation into prototype devices, such as hydrogen fuel cells, to see how they perform and to develop catalysts from other plants. Zou would like to also improve sustainability by reducing the energy consumption needed for the process.
This story is part of 
