Pushing manufacturers to make more resilient products will curb e-waste

by Daryl Lovell, Syracuse University

Credit: CC0 Public Domain

European lawmakers are considering new regulations that would push manufacturers to design products that last longer. It's part of a global effort to curb "throwaway" culture where people buy products, use them for a short while and then throw them away.

Cliff Davidson, professor of engineering and environmental engineering program director at Syracuse University, commends the move. Instead of a culture centered around buying new things, Prof. Davidson advocates for a culture where rentals are more common. He says Americans may rebel against the practice, but serious change is needed to disrupt the status quo.

Davidson says:

"This problem with electronic waste is that it's just the tip of the iceberg of all of our wastes… the real problem is about much more than e-waste. One of the key problems is that in order to keep many companies in profit mode, they need to have a continual demand for their product. What that means is they don't want to build a cell phone that lasts forever because there won't be people buying as many new cell phones as there are now. A lot of what we use, even outside of electronics, is built to eventually have problems with the physical device or to become less useful due to obsolescence (such as computers). If you have a laptop for more than a few years, it will probably be out of date because newer versions have more capabilities… it makes consumers want new ones. Manufacturers want to have continuous demand.

"There is one proposal that has been floated by others that I tend to agree with. It centers around the idea is that we shouldn't be purchasing devices, but rather we should be renting them. That goes for everything from cell phones and computers to dishwashers and dryers and washers, air conditioners, etc. If we practiced renting instead of buying, there would be a tremendous incentive for manufacturers to build products that last. The manufacturer would be responsible for repairs and they would build their products so that those repairs were minimal.

"I suspect that in some cultures, people would be willing to go rent rather than buy. But I expect Americans would rebel against that. It's a change in thinking about how you consume items and how you shop.

"Rebellion or not, we can't keep the status quo. We have to make changes and I do think putting more pressure on manufacturers to make more sustainable products is a step in the right direction."

'Right to repair' rules for electronics included in EU's Circular Economy Action Plan

During coronavirus, plunging power demand could signal economic woes

by University of Chicago

How do you measure the economic impact of coronavirus?

 A UChicago economist says to look at power demands. Credit: Shutterstock.com

With Americans largely self-isolating amid concerns about COVID-19, some of the hardest hit areas are already seeing electricity demand begin to weaken. Could this be a sign of things to come?


University of Chicago economist Steve Cicala examined what has happened to power demand in Northern Italy, which some say is about 11 days ahead of the U.S. trajectory of the novel coronavirus. An assistant professor at the Harris School of Public Policy, Cicala compiled regional grid data, adjusting for weather changes, and found that power demand has plunged in Northern Italy since the middle of February.

On Friday, Feb. 21, life in the region was largely normal. The following day, the Italian government began to institute quarantine measures. By Monday, power demand began to slow. As the chart below shows, there was then a bump in power just before the government instituted a national lockdown about two weeks later on March 10. About a week after that, power demand had fallen 18% compared to demand just prior to the quarantine measures.

An expert on the economics of environmental and energy policy regulation, Cicala said power demand could be a real-time indicator of the more widespread impacts on the Italian economy. And, what is happening in Italy could point to what the United States could expect in the coming weeks as states issue tighter restrictions on daily life.

Credit: Energy Policy Institute at the University of Chicago

"If paychecks and employment follow what is happening in the electricity-demand data, then there are a lot of people who will need help," said Cicala, a research affiliate for the Energy Policy Institute at the University of Chicago.

When there is a sharp shock in the economy, he explained, other indicators like employment may lag in reflecting the impact. This is because companies often lay off workers as a last resort, after they have already taken other measures like ramping down production or adjusting maintenance schedules. Conversely, electricity demand shows the more immediate change and is a broad measure of economic activity.

This pattern was on display during the last recession in the United States. U.S. power demand began to fall a month before the official start date of the recession in December 2007, according to the National Bureau of Economic Research—a date that was determined after an additional year of data had been collected.

As policymakers today consider which countermeasures may be necessary to buffer the economic effects of coronavirus, a real-time indicator of the economy's strength is of the utmost importance.

EU backs Italy's 'bold measures' to fight virus

Solar energy tracker powers down after 17 years

by Jessica Merzdorf, NASA's Goddard Space Flight Center

Banner Image: The Sun is Earth's primary power source. Energy from the Sun, called solar irradiance, drives Earth's climate, temperature, weather, atmospheric chemistry, ocean cycles, energy balance and more. Credit: NASA / Scott Wiessinger

After nearly two decades, the Sun has set for NASA's SOlar Radiation and Climate Experiment (SORCE), a mission that continued and advanced the agency's 40-year record of measuring solar irradiance and studying its influence on Earth's climate.


The SORCE team turned off the spacecraft on February 25, 2020, concluding 17 years of measuring the amount, spectrum and fluctuations of solar energy entering Earth's atmosphere—vital information for understanding climate and the planet's energy balance. The mission's legacy is continued by the Total and Spectral solar Irradiance Sensor (TSIS-1), launched to the International Space Station in December 2017, and TSIS-2, which will launch aboard its own spacecraft in 2023.

Monitoring Earth's "Battery"

The Sun is Earth's primary power source. Energy from the Sun, called solar irradiance, drives Earth's climate, temperature, weather, atmospheric chemistry, ocean cycles, energy balance and more. Scientists need accurate measurements of solar power to model these processes, and the technological advances in SORCE's instruments allowed more accurate solar irradiance measurements than previous missions.

"These measurements are important for two reasons," said Dong Wu, project scientist for SORCE and TSIS-1 at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Climate scientists need to know how much the Sun varies, so they know how much change in the Earth's climate is due to solar variation. Secondly, we've debated for years, is the Sun getting brighter or dimmer over hundreds of years? We live only a short period, but an accurate trend will become very important. If you know how the Sun is varying and can extend that knowledge into the future, you can then put the anticipated future solar input into climate models together with other information, like trace gas concentrations, to estimate what our future climate will be."

SORCE's four instruments measured solar irradiance in two complementary ways: Total and spectral.

Total solar irradiance, or TSI, is the total amount of solar energy that reaches the Earth's outer atmosphere in a given time. Sunspots (darkened areas on the Sun's surface) and faculae (brightened areas) create tiny TSI variations that show up as measurable changes in Earth's climate and systems. From space, SORCE and other solar irradiance missions measure TSI without interference from Earth's atmosphere.


SORCE's TSI values were slightly but significantly lower than those measured by previous missions. This was not an error—its Total Irradiance Monitor was ten times more accurate than previous instruments. This improved solar irradiance inputs into the Earth climate and weather models from what was previously available.

"The big surprise with TSI was that the amount of irradiance it measured was 4.6 watts per square meter less than what was expected," said Tom Woods, SORCE's principal investigator and senior research associate at the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP) in Boulder, Colorado. "That started a whole scientific discussion and the development of a new calibration laboratory for TSI instruments. It turned out that the TIM was correct, and all the past irradiance measurements were erroneously high."

"It's not often in climate studies that you make a quantum leap in measurement capability, but the tenfold improvement in accuracy by the SORCE / TIM was exactly that," said Greg Kopp, TIM instrument scientist for SORCE and TSIS at LASP.

SORCE's other measurements focused on spectrally-resolved solar irradiance (SSI): The variation of solar irradiance with wavelength across the solar spectrum, covering the major wavelength regions important to Earth's climate and atmospheric composition.

Besides the familiar rainbow of colors in visible light, solar energy also contains shorter ultraviolet and longer infrared wavelengths, both of which play important roles in affecting Earth's atmosphere. Earth's atmospheric layers and surface absorb different wavelengths of energy—for example, atmospheric ozone absorbs harmful ultraviolet radiation, while atmospheric water vapor and carbon dioxide absorb longer-wavelength infrared radiation, which keeps the surface warm. SORCE was the first satellite mission to record a broad spectrum of SSI for a long period, tracking wavelengths from 1 to 2400 nanometers across its three SSI instruments.

NASA's Solar Radiation and Climate Experiment, or SORCE, collected this data on total solar irradiance, the total amount of the Sun’s radiant energy, throughout Sept. 2017. Sunspots (darkened areas on the Sun’s surface) and faculae (brightened areas) create tiny TSI variations that show up as measurable changes in Earth’s climate and systems. Credit: NASA / Walt Feimer

"For public health, ozone chemistry and ultraviolet radiation are very important, and visible light is important for climate modeling," Wu said. "We need to know the solar variability at different wavelengths and compare these measurements with our models."

SORCE observed the Sun across two solar minima (periods of low sunspot activity), providing valuable information about variability over a relatively short 11-year period. But a longer record is needed to improve long-term predictions, Wu said.

Buying Time for an Aging Mission

SORCE was originally designed to collect data for just five years. Extending its lifespan to 17 required creative and resourceful engineering, said Eric Moyer, SORCE's mission director at Goddard.

SORCE's battery began to degrade in its eighth year of operations, no longer providing enough power to support consistent data collection. Unfortunately, the NASA instrument designed to take up its TSI measurements, Glory, was lost shortly after its 2011 launch, and the next instrument, the NOAA / U.S. Air Force Total solar irradiance Calibration Transfer Experiment (TCTE), would not launch until 2013. If SORCE could no longer operate, the ongoing solar irradiance record could be interrupted. Because the Sun changes very slowly—its sunspots and faculae follow an 11-year cycle, and some changes span decades or even centuries—a long, continuous record is essential for understanding how the Sun behaves.

The engineering team switched to daytime-only solar data collection, powering down the instruments and part of the spacecraft during the night part of the SORCE orbit. This plan effectively allowed the satellite to run with no functioning battery, Woods said—a groundbreaking engineering achievement.

"The operation and science teams at our partner organizations developed and implemented a completely new way to operate this mission when it appeared it was over because of battery capacity loss," said Moyer. LASP and Northrup Grumman Space Systems led the development of new operational software in order to continue the SORCE mission. "The small, highly dedicated team persevered and excelled when encountering operational challenges. I am very proud of their excellent accomplishment and honored to have had the opportunity to participate in managing the SORCE mission."

Continuing a Bright Legacy

As SORCE's time in the Sun ends, NASA's solar irradiance record continues with TSIS-1. The mission's two instruments measure TSI and SSI with even more advanced instruments that build on SORCE's legacy, said Wu. They have already enabled advances like establishing a new reference for the "quiet" Sun when there were no sunspots in 2019, and for comparing this to SORCE observations of the previous solar cycle minimum in 2008.

TSIS-2 is scheduled to launch in 2023 with identical instruments to TSIS-1. Its vantage point aboard its own spacecraft will give it more flexibility than TSIS-1's data collection aboard the ISS.

"We are looking forward to continuing the groundbreaking science ushered in by SORCE, and to maintaining the solar irradiance data record through this decade and beyond with TSIS-1 and 2," said LASP's Peter Pilewskie, principal investigator for the TSIS missions. "SORCE set the standard for measurement accuracy and spectral coverage, two attributes of the mission that were key to gaining insight into the Sun's role in the climate system. TSIS has made additional improvements that should further enhance Sun-climate studies."

"Solar irradiance measurements are very challenging, and the SORCE team proposed a different way, a new technology, to measure them," said Wu. "Using advanced technology to advance our science capability, SORCE is a very good example of NASA's spirit."SORCE satellite: A Decade in the Sun

Middle-aged entrepreneurs fare better than twentysomethings

by Peter Dizikes, Massachusetts Institute of Technology

Credit: CC0 Public Domain

Two years ago, MIT economist Pierre Azoulay started a lively discussion when a working paper he co-authored, "Age and High-Growth Entrepreneurship," revealed a surprising fact about startup founders: Among firms in the top 1/10 of the top 1 percent, in terms of growth, the average founder's age is 45. That's contrary to the popular image of valuable startups being the sole domain of twentysomething founders, such as Mark Zuckerberg of Facebook.

The paper, written with Benjamin Jones of Northwestern University, J. Daniel Kim of the University of Pennsylvania, and Javier Miranda of the U.S. Bureau of the Census, has now been officially published, in the journal American Economics Review: Insights. MIT News spoke to Azoulay, the International Programs Professor of Management at the MIT Sloan School of Management, about the finding and the discussion it has generated.

Q: What has been the response of people to the study?

A: We're documenting a fact, and that fact either accords with people's intuitions, or it doesn't. Some people are genuinely surprised because they've lived in the current zeitgeist, and then once they start thinking about it, they say, "Ah, it makes sense." And then there are people who say, "Oh, I knew it all along!" But Silicon Valley venture capitalists have studiously avoided engaging with what we've done. And I don't know why.

I think one line of [venture capitalist] skepticism is to say, "Well, you may well be right, but you're studying the one-in-a-thousand firm, and we're [investing in] the one-in-a-million firm." Which is sort of like restating that Apple, Microsoft, and Google were founded by young people.

Yes, we already knew it is possible for very large, successful firms to be founded by very young people. The question is: Is it likely?

Q: As you continue to think about this subject, is it possible to say what accounts for the success of relatively older entrepreneurs? Experience, intellectual capital, greater business connections—what matters?

A: All of those things are not mutually exclusive, and they're all likely to play a role. They just need to be studied separately, if you will. We have to remain agnostic. But there is one key point in my view. Forget experience: How about just knowledge? I like to say there is no such thing as a 25-year-old biotech entrepreneur. That person just doesn't exist, because you need a Ph.D. and three postdocs [to gain high-level knowledge]. There are lots of fields where if you want to make a contribution, you have to bring yourself to the frontier of knowledge in a domain, and that takes time. And that's not going to be the realm of the 22-year-old.

Beyond the big platform IT companies, if you're thinking about the broader swath of entrepreneurship across a multiplicity of sectors, then you have to acknowledge this point. In some sense, if you recognize the diversity of startups, the [founder's] age number is going to be higher than if you're only focused on super-high-value Silicon Valley internet companies. So we need a basic attitude adjustment.

Q. Even as people mythologize the young startup founder, there is also a tech-sector ethos that heralds serial entrepreneurship and tolerates failure, because you're taking risks and learning by doing. Isn't that one Silicon Valley notion that might correspond to what you discovered?

A: Yes, one thing that could explain our results is entrepreneurship being an activity you can learn to do better over time. That's certainly something we've heard. We can't pin it down, but if I had to think of the most likely stories, that's certainly one. Even within a particular sector that demands a certain amount of intellectual capital, holding that constant, even within biotech or clean energy, you might think there is something about learning by founding, which is going to lead to a correlation between success and a higher age for founders.The 20-year-old entrepreneur is a myth, according to study

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Provided by Massachusetts Institute of Technology 

This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

How fungi's knack for networking boosts ecological recovery after bushfires

by Adam Frew, Andy Le Brocque, Dale Nimmo, Eleonora Egidi, 

Jodi Price and Leanne Greenwood, The Conversation

Credit: Doug Beckers/Flickr, CC BY-SA

The unprecedented bushfires that struck the east coast of Australia this summer killed an estimated one billion animals across millions of hectares.


Scorched landscapes and animal corpses brought into sharp relief what climate-driven changes to wildfire mean for Australia's plants and animals.

Yet the effects of fire go much deeper, quite literally, to a vast and complex underground world that we know stunningly little about, including organisms that might be just as vulnerable to fire, and vital to Australia's ecological recovery: the fungi.

Plants and fungi: a match made underground

The aftermath of wildfires can make landscapes appear devoid of life. Yet under the ash beds lies a vast living network of fungi.

One group of fungi, called arbuscular mycorrhizal (AM) fungi, form symbiotic relationships with most of the world's land plants. This means most plants and AM fungi rely on each other to grow and thrive.

Extensive networks of AM fungal mycelium (a vegetative part of a fungus, akin to plant roots) explore the soil to access nutrients beyond the reach of their plant partners. The mycelium forms a fungal underground highway, transporting the valuable nutrients back to the plants.

Fungi play a crucial role in ecosystems around the world. 

Amanita sp, Geastrum sp and Aseroe sp. Credit: Adam Frew

Beyond nutrients, AM fungi can influence all aspects of plant ecology, such as seedling establishment, plant growth, defence against herbivores, and competition between different plant species. In fact, the number of species and abundance of AM fungi determine the success and diversity of plants.

In return for the nutrients they provide, AM fungi receive sugar made by plants through photosynthesis. For many species, this means without a plant host the fungi won't last.


The responses of plants and AM fungi to fire are therefore deeply intertwined: the recovery of one is dependent on the other. Yet ecologists are only beginning to learn how fire affects fungi and what role they might have in hastening ecosystem recovery following wildfires.

Fungi and fire: what do we know?

Studies have shown fungi living near the soil surface are particularly susceptible to fire, often killed by high soil temperatures as the fire passes over. Fungi further below the surface are relatively more protected, and may provide the nuclei for recovery.

Fungi provide access to nutrients such as phosphorus, and plants provide carbon as sugar and fats. Credit: Adam Frew via BioRender

But, as with animals, surviving fire is only half the battle. When fire removes vegetation, it suddenly halts sugar and fats plants produce, delivered to the fungi below-ground.

Another challenge is the ways fire influences the underground world, such as changes in soil acidity, soil carbon, nutrient dynamics, and soil water. For instance, soils with more acidity tend to have less diversity of AM fungi.

The combination of high temperatures and changed conditions appear to take a toll on fungi: a 2017 meta-analysis of 29 studies found fire reduces the number of fungal species by about 28%. And given the severity of last summer's bushfires, we can expect that many fungal communities below the surface have been lost, too.

Lose fungi, lose function

When fire hits, the community of AM fungi may lose less resistant species. This is important because studies show different species of AM fungi are better at supporting their plant partners in different ways. Some are better at providing nutrients, while others are more helpful with defending plants from disease and herbivores.

Arbuscular mycorrhizal fungi colonising a plant root. Credit: Adam Frew

Changes in the number and types of AM fungal species can strongly determine how well plants recover, and can influence the whole ecosystem after fire. For example, plants could be left more vulnerable to disease if fungi supporting native plant chemical or physical defences are reduced by fire.

Since we know fungi are particularly important to plants in times of ecological stress, their role may be paramount in harsh post-fire landscapes. But while firefighters and wildlife carers have gone to inspiring lengths to protect plants and animals, we know little about how to help AM fungi recovery from the bushfires, or if help is even necessary.

Helping fungi help ecosystems

Research from last year showed reintroducing AM fungal communities (usually as an inoculant or biofertiliser) to degraded and disturbed landscapes can increase plant diversity by around 70%, encourage recovery of native plants, and suppress invasive weeds.

Fire tends to change what species of arbuscular mycorrhizal fungi are present in the soil as ecosystems recovery. Credit: Adam Frew via BioRender

How exactly fungi and fire interact remains an ecological mystery. 

Credit: Coprinus sp. Adam Frew

Amanita muscaria (Fly agaric). Credit: Adam Frew

Fire tends to change what species of arbuscular mycorrhizal fungi are present in the soil as ecosystems recovery. Credit: Adam Frew via BioRender

How exactly fungi and fire interact remains an ecological mystery. Credit: Coprinus sp. Adam Frew

Taking a similar approach and actively putting fungi back into fire-affected environments could ensure more rapid or more complete recovery of native vegetation, including the survival of endangered plant species threatened by the fires.

However, it's important to consider which AM fungi are reintroduced. They should be species normally present in the local area, and suited to support recovering plant communities.

So as climate change leads to more frequent and intense bushfires, could fungi form a fundamental component of fire recovery efforts? Maybe.

But there is so much we're yet to learn about these ancient and complex relationships. We're only beginning to scratch the surface.Underground fungal relationships key to thriving plants

Provided by The Conversation 

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New study finds immune cells can defend against multiple viruses

by Brita Belli, Yale University

Credit: CC0 Public Domain

An underlying virus does not stop the body's immune system from launching a strong defense against a second, newly introduced virus, according to a Yale-led study that appears in the March 9 online edition of the journal PLOS Neglected Tropical Diseases.

For the study, Yale researchers obtained blood samples from patients from India with dengue infection, working in partnership with investigators from The National Institute of Mental Health and NeuroSciences in India and their colleagues at Apollo Hospital in Bangalore. They then infected these samples with the Zika virus and measured the cells' immune response using advanced cell-profiling technology. The researchers found that the underlying dengue infection did not stop the cells from launching a robust immune response against the newly introduced Zika virus.

"The message from our paper is that your innate immune system is ready to launch a very powerful response to a new pathogen," said Ruth Montgomery, professor of medicine and epidemiology and associate dean for scientific affairs, and the paper's lead author.

Montgomery and her team tested samples from both dengue patients and healthy controls from India and found that the underlying dengue infection did not impair new immune responses to the Zika virus. Specifically, researchers noted an increase in small proteins called cytokines, which are related to fighting off infection, in 36 individual cell subsets when Zika was introduced.

"Patients with acute dengue still had a strong immune response to the Zika virus," said Montgomery. "Their immune response was not diminished."

Both the dengue virus and Zika virus are mosquito-borne human pathogens that have caused significant public health concern across the globe. There are some 50-100 million estimated dengue infections, leading to fever, headaches, joint pain, and more severe shock syndrome; the Zika virus has been shown to be devastating to babies in utero, and has led to over 6,700 cases of deformities and neurological damage in newborns. Because the vectors for disease transmission are the same, certain regions are highly prone to both, including Brazil, which had a Zika epidemic in 2015. When the dengue samples were collected from India for the study, Zika was not yet a public health threat in that country. By 2018, that had changed, with 94 confirmed Zika cases, and widespread monitoring.

These findings provide a much more in-depth look at the body's response to viruses at the single-cell level, which Montgomery noted are consistent with existing literature. The research was part of a the HIPC consortium funded by the National Institutes of Health to better understand human immunology, infectious disease, and vaccination responses.

To measure immune response, she and her team used mass cytometry or CyTOF (Cytometry by Time-of-Flight), a state-of-the-art method for simultaneously revealing multiple components of the responses of distinct immune cell populations. Analysis of the results was done using SAUCIE, a novel deep-learning algorithm developed by a team in the lab of Smita Krishnaswamy, assistant professor of genetics and computer science at Yale. Montgomery, director of the Yale CyTOF facility, said Yale is at the forefront of advanced cell analysis, and one of the first academic medical centers with a CyTOF Imaging Mass Cytometer, which further extends its capabilities.

The findings can help guide scientists' understanding of all emerging infectious diseases, including coronavirus, something Montgomery's lab is now actively investigating.

"We are set up to investigate human immune cell response to viruses and have several collaborations currently underway to collect samples related to the coronavirus," Montgomery said. "We have containment facilities and excellent virologists at Yale, and there is a lot of activity right now," she added.

Zika vaccine induces potent Zika and dengue cross-neutralizing antibodies

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More information: Yujiao Zhao et al. Single cell immune profiling of dengue virus patients reveals intact immune responses to Zika virus with enrichment of innate immune signatures, PLOS Neglected Tropical Diseases (2020). DOI: 10.1371/journal.pntd.0008112

Reanalysis of global amphibian crisis study finds important flaws

by University of California - Berkeley

Rana clamitans. Credit: Max Lambert.

Though biodiversity is in crisis globally, amphibians in particular face a variety of threats. One such threat comes from pathogens like the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Bd causes chytridiomycosis, a disease that research indicates contributes to the decline of some amphibians. New research, however, now calls into question some prior evidence that links the widespread pathogen to hundreds of amphibian declines.


Last year in the journal Science, a research review by Scheele et al. concluded that Bd caused the decline of at least 501 amphibian species, of which 90 have gone extinct. That paper suggested that species losses due to Bd are "orders of magnitude greater than for other high-profile wildlife pathogens." But a recent reanalysis led by Berkeley researchers found that Scheele et al."s main conclusions lack evidence and are unreproducible.

In a Comment published today in Science, the group conducting the reanalysis—including lead authors Max Lambert and Molly Womack, who are postdocs in the lab of professor Erica Rosenblum in the Department of Environmental Science, Policy, and Management (ESPM)—identified a number of data deficiencies and methodological issues in the Scheele et al. study. Working through the methods and datasets, they faced challenges in reproducing conclusions while identifying numerous instances of missing data. In some cases, data gaps failed to link Bd to species declines—even for many species which were previously reported with high certainty that Bd was the cause.

Atelopus zeteki. Credit: Allison Byrne.

Lambert and Womack note that their reanalysis does not minimize the role Bd has played in amphibian declines and that "chytridiomycosis has irrefutably harmed amphibians."

A number of co-authors involved in the reanalysis had previously studied the harmful effects of the chytrid fungus on amphibians in California and Central America. For some species, the data make clear that amphibian chytrid fungus, which has received tremendous attention, has contributed to declines. However, Lambert, Womack, and their collaborators found that the evidence in Scheele et al."s analysis is negligible—or even absent—for many important species.

They state that it remains unclear exactly how many and which amphibian species have been harmed by Bd. Relative to other threats that amphibians face, the role chytrid plays in global declines is also uncertain. In many cases, according to the Science comment, the cause of amphibian declines remains a mystery.

The reanalysis authors argue that transparent data collection and analysis are crucial—both for science and conservation efforts. "It is more critical than ever for scientists to provide responsible narratives based on transparent and reproducible data and methods," says Lambert. "Doing so will produce better science and more effective conservation."Mass amphibian extinctions globally caused by fungal disease

More information: Max R. Lambert et al. Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity", Science (2020). DOI: 10.1126/science.aay1838

INTERSPECIES SEX 

Female toads seek a good man—even if he's another species

by Brian Owens, Inside Science, American Institute of Physics

Credit: CC0 Public Domain

The one thing about species that most people probably remember from high school science class is that when it comes to sex, they generally stick to their own kind. Hybrids happen, but they are usually thought to be accidental, and the results typically have drawbacks—think of how a horse crossed with a donkey results in a sterile mule.

But the reality is more complicated than that. Karin Pfennig, an evolutionary biologist at the University of North Carolina at Chapel Hill, has for years been observing something strange in the southwestern U.S. Female plains spadefoot toads sometimes choose to ignore the males of their own species, and instead mate with males from a closely related species, the Mexican spadefoot toad.

The toads do this under very specific circumstances, said Catherine Chen, a behavioral ecologist who works in Pfennig's lab. Their tadpoles grow up in temporary ponds, and when the ponds are particularly shallow the female plains spadefoots prefer to mate with Mexican spadefoots. This seems to give their offspring a better chance of survival.

"Hybrid tadpoles develop more quickly, so they are more likely reach maturity before the shallow ponds dry up," said Chen.

Now, Chen and Pfennig have found that the female plains spadefoots don't just choose their cross-species dates at random; they look for specific traits that signal they are getting a high-quality mate. They say it is the first time that such cross-species sexual selection has been observed in animals. The work is published today in the journal Science.

In previous mating experiments, the researchers had discovered that hybrid offspring whose fathers' mating call had a slower "pulse rate"—the trilling quality of the call—tended to do better than those whose father had a fast pulse rate. "We wondered, do the females care? Can they tell the difference between high- and low-quality males?" said Chen.

So they placed female plains spadefoots in a simulated pond in the lab, and played recordings of Mexican spadefoot males with different pulse rates. They found that the females did indeed prefer to seek out the males with slower pulse rates.

Chen says they are not sure why males with slower pulse rates make better mates for plains spadefoot females. "Maybe a slower pulse rate means they're in better condition or is associated with certain genes linked to fitness, but we can't say for sure right now," she said.

Interestingly, Mexican spadefoot females have a different idea of what makes a good mate. They don't pay any attention to the pulse rate of the males' call, and instead focus on overall call rate, preferring mates that make more calls in a shorter amount of time—maybe because that takes more energy and so indicates good health.

The hybrid toads that result from crosses between plains females and Mexican males look different from purebred toads, but they are not in the process of forming a new species, said Chen. Hybrid males are sterile, and the hybrid females can mate with either parent species. The researchers don't yet know if these hybrid females have a preference for one or the other, or whether that preference might change under different circumstances.

Marlene Zuk, an evolutionary biologist at the University of Minnesota in St. Paul, says the boundaries between species have always been fuzzier than what most people assume, and the toads' situation is probably not that unique.

"The idea that there is hybridization going on and that it does not result in everyone being struck by lightning is not completely novel," she said. What is new, however, is the idea of females of one species exerting sexual selection on the males of another species—especially by selecting for traits that are different from those preferred by that species' own females. "You've got this whole separate process going on that is independent of what females of that species are doing," she said.

This shows that the effects of hybridization can be much bigger and more important in the development of a species than many biologists thought, said Chen. "We usually think of hybridization as random, and usually bad," she said. "But it doesn't have to be. It can have important evolutionary and ecological effects."Male orb-weaving spiders cannibalized by females may be choosy about mating

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More information: Catherine Chen et al. Female toads engaging in adaptive hybridization prefer high-quality heterospecifics as mates, Science (2020). DOI: 10.1126/science.aaz5109

Darkness, not cold, likely responsible for dinosaur-killing extinction

by Lauren Lipuma, American Geophysical Union

Roughly 66 million years ago an asteroid slammed into the Yucatan peninsula. New research shows darkness, not cold, likely drove a mass extinction after the impact. Credit: NASA

New research finds soot from global fires ignited by an asteroid impact could have blocked sunlight long enough to drive the mass extinction that killed most life on Earth, including the dinosaurs, 66 million years ago.

The Cretaceous–Paleogene extinction event wiped out about 75 percent of all species on Earth. An asteroid impact at the tip of Mexico's Yucatán Peninsula caused a period of prolonged cold and darkness, called an impact winter, that likely fueled a large part of the mass extinction. But scientists have had a hard time teasing out the details of the impact winter and what the exact mechanism was that killed life on Earth.

A new study in AGU's journal Geophysical Research Letters simulates the contributions of the impact's sulfur, dust, and soot emissions to the extreme darkness and cold of the impact winter. The results show the cold would have been severe but likely not devastating enough to drive a mass extinction. However, soot emissions from global forest fires darkened the sky enough to kill off photosynthesizers at the base of the food web for well over a year, according to the study.

"This low light seems to be a really big signal that would potentially be devastating to life," said Clay Tabor, a geoscientist at the University of Connecticut and lead author of the new study. "It seems like these low light conditions are a probable explanation for a large part of the extinction."

The results help scientists better understand this intriguing mass extinction that ultimately paved the way for humans and other mammals to evolve. But the study also provides insight into what might happen in a nuclear winter scenario, according to Tabor.

"The main driver of a nuclear winter is actually from soot in a similar type situation," Tabor said. "What it really highlights is just how potentially impactful soot can be on the climate system."

The impact and extinction

The Chicxulub asteroid impact spewed clouds of ejecta into the upper atmosphere that then rained back down to Earth. The returning particles would have had enough energy to broil Earth's surface and ignite global forest fires. Soot from the fires, along with sulfur compounds and dust, blocked out sunlight, causing an impact winter lasting several years. Previous research estimates average global temperatures plummeted by at least 26 degrees Celsius (47 degrees Fahrenheit).


Scientists know the extreme darkness and cold were devastating to life on Earth but are still teasing apart which component was more harmful to life and whether the soot, sulfate, or dust particles were most disruptive to the climate.

 

Credit: American Geophysical Union

In the new study, Tabor and his colleagues used a sophisticated climate model to simulate the climatic effects of soot, sulfates, and dust from the impact.

Their results suggest soot emissions from global fires absorbed the most sunlight for the longest amount of time. The model showed soot particles were so good at absorbing sunlight that photosynthesis levels dropped to below one percent of normal for well over a year.

"Based on the properties of soot and its ability to effectively absorb incoming sunlight, it did a very good job at blocking sunlight from reaching the surface," Tabor said. "In comparison to the dust, which didn't stay in the atmosphere for nearly as long, and the sulfur, which didn't block as much light, the soot could actually block almost all light from reaching the surface for at least a year."

A refuge for life

The darkness would have been devastating to photosynthesizers and could explain the mass extinction through a collapse of the food web, according to the researchers. All life on Earth depends on photosynthesizers like plants and algae that harvest energy from sunlight.

Interestingly, the temperature drop likely wasn't as disturbing to life as the darkness, according to the study.

"It's interesting that in their model, soot doesn't necessarily cause a much larger cooling when compared other types of aerosol particles produced by the impact-but soot does cause surface sunlight to decline a lot more," said Manoj Joshi, a climate dynamics professor at the University of East Anglia in the United Kingdom who was not connected to the new study.

In regions like the high latitudes, the results suggest oceans didn't cool significantly more than they do during a normal cycle of the seasons.

"Even though the ocean cools by a decent amount, it doesn't cool by that much everywhere, particularly in the higher latitude regions," Tabor said. "In comparison to the almost two years without photosynthetic activity from soot, it seems to be a secondary importance."

As a result, high latitude coastal regions may have been refuges for life in the months after the impact. Plants and animals living in the Arctic or Antarctic are already used to large temperature swings, extreme cold, and low light, so they may have had a better chance of surviving the impact winter, according to the researcher

Millions of years of soot deposits reveal wildfire cycles related to climate change
More information: Clay R. Tabor et al. Causes and Climatic Consequences of the Impact Winter at the Cretaceous‐Paleogene Boundary, Geophysical Research Letters (2020). DOI: 10.1029/2019GL085572


Julia Brugger et al. Baby, it's cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous, Geophysical Research Letters (2016). DOI: 10.1002/2016GL072241
Journal information: Geophysical Research Letters

How oceans and atmospheres move heat around on Earth and other planetary bodies

by Massachusetts Institute of Technology

This visualization shows the Gulf Stream's sea surface currents and and temperatures. Credit: MIT/JPL project entitled Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2)

Imagine a massive mug of cold, dense cream with hot coffee poured on top. Now place it on a rotating table. Over time, the fluids will slowly mix into each other, and heat from the coffee will eventually reach the bottom of the mug. But as most of us impatient coffee drinkers know, stirring the layers together is a more efficient way to distribute the heat and enjoy a beverage that's not scalding hot or ice cold. The key is the swirls, or vortices, that formed in the turbulent liquid.

"If you just waited to see whether molecular diffusion did it, it would take forever and you'll never get your coffee and milk together," says Raffaele Ferrari, Cecil and Ida Green Professor of Oceanography in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

This analogy helps explain a new theory on the intricacies the climate system on Earth—and other rotating planets with atmospheres and/or oceans—outlined in a recent PNAS paper by Ferrari and Basile Gallet, an EAPS visiting researcher from Service de Physique de l'Etat Condensé, CEA Saclay, France.

It may seem intuitive that Earth's sun-baked equator is hot while the relatively sun-deprived poles are cold, with a gradient of temperatures in between. However, the actual span of that temperature gradient is relatively small compared to what it might otherwise be because of the way the Earth system physically transports heat around the globe to cooler regions, moderating the extremes.

Otherwise, "you would have unbearably hot temperatures at the equator and [the temperate latitudes] would be frozen," says Ferrari. "So, the fact that the planet is habitable, as we know it, has to do with heat transport from the equator to the poles."

Yet, despite the importance of global heat flux for maintaining the contemporary climate of Earth, the mechanisms that drive the process are not completely understood. That's where Ferrari and Gallet's recent work comes in: their research lays out a mathematical description of the physics underpinning the role that marine and atmospheric vortices play in redistributing that heat in the global system.

Ferrari and Gallet's work builds on that of another MIT professor, the late meteorologist Norman Phillips, who, in 1956, proposed a set of equations, the "Phillips model," to describe global heat transport. Phillips' model represents the atmopshere and ocean as two layers of different density on top of each other. While these equations capture the development of turbulence and predict the distribution of temperature on Earth with relative accuracy, they are still very complex and need to be solved with computers. The new theory from Ferrari and Gallet provides analytical solutions to the equations and quantitatively predicts local heat flux, energy powering the eddies, and large-scale flow characteristics. And their theoretical framework is scalable, meaning it works for eddies, which are smaller and denser in the ocean, as well as cyclones in the atmosphere that are larger.


Setting the process in motion

The physics behind vortices in your coffee cup differ from those in nature. Fluid media like the atmosphere and ocean are characterized by variations in temperature and density. On a rotating planet, these variations accelerate strong currents, while friction—on the bottom of the ocean and atmosphere—slows them down. This tug of war results in instabilities of the flow of large-scale currents and produces irregular turbulent flows that we experience as ever-changing weather in the atmosphere.

Vortices—closed circular flows of air or water—are born of this instability. In the atmosphere, they're called cyclones and anticyclones (the weather patterns); in the ocean they're called eddies. In both cases, they are transient, ordered formations, emerging somewhat erratically and dissipating over time. As they spin out of the underlying turbulence, they, too, are hindered by friction, causing their eventual dissipation, which completes the transfer of heat from the equator (the top of the hot coffee) to the poles (the bottom of the cream).

Zooming out to the bigger picture

While the Earth system is much more complex than two layers, analyzing heat transport in Phillips' simplified model helps scientists resolve the fundamental physics at play. Ferrari and Gallet found that the heat transport due to vortices, though directionally chaotic, ends up moving heat to the poles faster than a more smooth-flowing system would. According to Ferrari, "vortices do the dog work of moving heat, not disorganized motion (turbulence)."

It would be impossible to mathematically account for every single eddy feature that forms and disappears, so the researchers developed simplified calculations to determine the overall effects of vortex behavior, based on latitude (temperature gradient) and friction parameters. Additionally, they considered each vortex as a single particle in a gas fluid. When they incorporated their calculations into the existing models, the resulting simulations predicted Earth's actual temperature regimes fairly accurately, and revealed that both the formation and function of vortices in the climate system are much more sensitive to frictional drag than anticipated.

Ferrari emphasizes that all modeling endeavors require simplifications and aren't perfect representations of natural systems—as in this instance, with the atmosphere and oceans represented as simple two-layer systems, and the sphericity of the Earth is not accounted for. Even with these drawbacks, Gallet and Ferrari's theory has gotten the attention of other oceanographers.

"Since 1956, meteorologists and oceanographers have tried, and failed, to understand this Phillips model," says Bill Young, professor of physical oceanography at Scripps Institution of Oceanography, "The paper by Gallet and Ferrari is the first successful deductive prediction of how the heat flux in the Phillips model varies with temperature gradient."

Ferrari says that answering fundamental questions of how heat transport functions will allow scientists to more generally understand the Earth's climate system. For instance, in Earth's deep past, there were times when our planet was much warmer, when crocodiles swam in the arctic and palm trees stretched up into Canada, and also times when it was much colder and the mid-latitudes were covered in ice. "Clearly heat transfer can change across different climates, so you'd like to be able to predict it," he says. "It's been a theoretical question on the minds of people for a long time."

As the average global temperature has increased more than 1 degree Celsius in the past 100 years, and is on pace to far exceed that in the next century, the need to understand—and predict—Earth's climate system has become crucial as communities, governments, and industry adapt to the current changing environment.

"I find it extremely rewarding to apply the fundamentals of turbulent flows to such a timely issue," says Gallet, "In the long run, this physics-based approach will be key to reducing the uncertainty in climate modeling."

Following in the footsteps of meteorology giants like Norman Phillips, Jule Charney, and Peter Stone, who developed seminal climate theories at MIT, this work too adheres to an admonition from Albert Einstein: "Out of clutter, find simplicity.Study: Climate change reshaping how heat moves around globe

More information: Basile Gallet et al. The vortex gas scaling regime of baroclinic turbulence, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1916272117
Journal information: Proceedings of the National Academy of Sciences