NEWS AND NOTES ABOUT SCIENCE
PLANTS WON’T SAVE US FROM GLOBAL WARMING, A NEW STUDY SUGGESTS
The last time the atmosphere contained as much carbon dioxide as now, dinosaurs roamed what was a verdant landscape. The Earth’s lushness was at least partly caused by the abundance of CO2, which plants use for photosynthesis. That has led to the idea that more CO2 in the atmosphere could create a literally greener planet.
Today, plants and soil around the world absorb roughly a quarter of the greenhouse gases that humans release into the atmosphere, helping the Earth avoid some of the worst effects of climate change. In an ideal situation, as levels of carbon dioxide increased, plants would soak up more of these emissions, helping to fuel their growth.
But in a recent study published in the journal Nature, researchers found that under a warming climate, rather than absorbing more greenhouse gas emissions, plants and soil may start absorbing less, accelerating the rate of change.
“We have this image of the planet getting very, very green as we move into the future,” said Pierre Gentine, an environmental engineering professor at Columbia University and an author of the study. “But it may be the opposite.”
Researchers know that atmospheric concentrations of carbon dioxide increase in dry years, a sign the Earth is absorbing fewer emissions.
When the soil is dry, plants are stressed and cannot absorb as much CO2 to perform photosynthesis. At the same time, because dry conditions are often accompanied by warm temperatures, microorganisms in the soil, which are more productive when it’s warm, release more CO2.
As the climate changes, there will be more years of extreme weather. That means extreme droughts, followed by years of heavier than normal rainfall, will become more likely. The researchers wondered if those conditions would balance out.
To check, they ran four different climate simulations and used satellite observations. The goal was to see the effect that soil moisture had on Earth’s ability to absorb greenhouse gas emissions.
Though plants and soil could absorb more CO2 in the wetter years, it did not make up for their reduced ability to absorb CO2 when soil was dry.
Even when a drought year is followed by a year as wet as the previous one was dry, it is not enough to compensate for the dry year. Kendra Pierre-Louis
FROM MORNING PERSONS AND NIGHT OWLS, AN ARSENAL OF DNA
Early to bed and early to rise is a maxim that’s easy to follow for some people and devilishly hard for others.
Now, in a study published recently in Nature Communications, researchers curious about the genetic underpinnings of chronotype — whether you are a morning person, a night owl or somewhere in between — looked at about 700,000 people’s genomes. They identified 351 variations that may be connected to when people go to bed. The study goes on to suggest tantalizing links between chronotype and mental health.
The researchers drew on data from 23andMe, the genetic testing company, and the UK Biobank, which tracks hundreds of thousands of volunteer subjects in Britain, about 85,000 of whom wear activity monitors that record their movements.
Those data were key, said Michael Weedon, a bioinformaticist at University of Exeter in England and an author of the new paper; earlier studies had relied only on people’s subjective opinions of whether they were morning people. Using the activity monitors, however, the team was able to confirm that selfreported morning people did go to sleep earlier — and people with the most morning-linked gene variants went to bed 25 minutes earlier than people with the fewest.
The genes flagged in the study play a wide variety of roles in the body.
Many seem to play a role in brain tissues, and others are already known to be central to the body’s circadian rhythm. A few were active mainly in the retina, and the people who possessed an uncommon version of one of these genes had an increased chance of being night owls, said Samuel Jones, a researcher at the University of Exeter and the study’s lead author. That could imply a potential a connection between how the eye responds to sunlight and when a person sleeps.
Another gene was involved in the body’s processing of caffeine and nicotine. Continued study of these and the other genes could provide leads for future work on the biology of sleep timing.
When the researchers crunched
the numbers on chronotype’s connection to mental health, they also found that self-identified morning people reported a higher level of general well-being. People in this group also were less likely to report having depression or schizophrenia, in line with epidemiological studies suggesting that evening people struggle with mental health. Veronique Greenwood
YOU FLUSHED THE TOILET. THEY MADE SOME BRICKS.
It may be unpleasant to contemplate the ultimate fate of all the material from your own body that you flush down the pipes. But it’s time we talk about biosolids — the disinfected leftovers from the water treatment process.
This sandy material contains nutrient-rich organic content that’s good for agriculture. But it also makes nice bricks, according to Abbas Mohajerani, a civil engineer at Royal Melbourne Institute of Technology University in Australia.
“Biosolids bricks look the same, smell the same and have similar physical and mechanical properties as normal fired clay bricks,” he said.
And as long as it’s done locally, he thinks that recycling stockpiles of leftover biosolids into bricks could save land and energy, and reduce carbon emissions.
Worldwide, humans produce vast quantities of biosolids. In a single day, New York City alone makes 1,200 tons, or about 50 truckloads.
The old solution was to dump them into the sea or a landfill. But more treatment plants and stricter regulations are prompting people to find clever ways to recycle the dried sludge. About 50 to 70 percent of it is now used, mostly to boost soil quality or fertilize crops. But the rest remains unused or stockpiled. In the United States, it’s estimated that nearly a third of the 7 million to 8 million tons of biosolids produced each year still end up in landfills. As organic particles in the waste decompose, greenhouse gases such as carbon dioxide escape and can contribute to global warming.
Over the course of half a decade, Mohajerani and a team of research- ers collected biosolids from two wastewater treatment plants in Melbourne and mixed them with soil to make hybrid bricks of varying proportions. They fired them for 10 hours, at nearly 2,000 degrees Fahrenheit, and cooled them, then compared them in tests to normal bricks.
The team’s findings, published recently in the journal Buildings, ranked the biosolid bricks similar in quality to those currently on the market. And the researchers proposed that incorporating just 15 percent biosolids into all the bricks made around the world each year would eliminate all of our leftovers.
Depending on the amount of biosolids used, how they were treated and how long they sat around, the biosolid bricks were safe, durable and in some ways energy efficient. Joanna Klein
FLYING SQUIRRELS THAT GLOW PINK IN THE DARK
One spring night in Wisconsin, John Martin, a biologist, was in his backyard with an ultraviolet flashlight. Suddenly, a hot-pink squirrel flew by.
It was a southern flying squirrel, a small, furry creature most active at dawn and dusk. Under most circumstances, it has a warm brown color. But in the beam of Martin’s flashlight, it sported a gaudy Day-Glo hue closer to something you might see in a nightclub or a Jazzercise class circa 1988.
told his colleagues at Northland College, but of course, everyone was pretty skeptical,” said Allison Kohler, a graduate student at Texas A&M University.
Martin asked Kohler, then a student at Northland, to look into it. After examining more than 100 specimens of flying squirrels across two museum collections and spotting five more squirrels under UV light in the wild, the researchers and their colleagues reported surprising results last week in the Journal of Mammalogy: The pink is real.
Three different species of flying squirrel — including Humboldt’s flying squirrel — turned that color under ultraviolet illumination.
What the flying squirrels get out of it is still a mystery. Confirming that the squirrels are even capable of seeing in ultraviolet wavelengths will require additional study, Kohler said.
The researchers have some hypotheses concerning what’s behind the squirrels’ Day-Glo displays. Ultraviolet rays are abundant during the dawn and dusk periods when the squirrels are moving around. So it is reasonable to expect that the fluorescence is visible to other organisms even when there are no biologists with UV flashlights in the vicinity.
The vivid pink color might have evolved to confuse the owls who prey on the squirrels. Those birds of prey fluoresce in precisely the same hue themselves; a flying squirrel may look, superficially at least, like a flying owl.
Or, if it’s confirmed that the squirrels see UV, the color might have something to do with mating or signaling to other flying squirrels. Veronique Greenwood
GOVERNMENT SHUTDOWN IS BLAMED FOR DEATH OF SOME JOSHUA TREES
The partial government shut“He down ended after 35 days, but conservationists have warned that its effect may be felt for hundreds of years in at least one part of the country: Joshua Tree National Park.
The Southern California park, which is larger than Rhode Island and famed for its dramatic rock formations and the spiky-leafed Joshua trees from which it takes it name, had only a skeleton crew of workers during the shutdown.
With most of its park rangers furloughed, vandals and inconsiderate guests ran amok. Gates and posts were toppled, new roads carved through the desert by unauthorized off-road drivers, and a small number of the park’s thousands of Joshua trees were outright destroyed, conservationists said.
Pictures posted to social media showed trees that were chopped down or that appeared to have been driven over by cars. The sensitive ecosystem of desert and craggy rock formations that surrounds them was littered with garbage and other signs of illegal camping.
Most visitors to the park were well-behaved, said John Lauretig, a former park ranger who now runs Friends of Joshua Tree, a nonprofit group that organized a small army of volunteers to help clean the park during the shutdown.
“It was just a few vandals or people acting out of ignorance that caused these problems,” he said, reflecting on the broken trees. “Hopefully it’s not malice. Maybe they just didn’t see them.”
Replanting and growing the park’s namesake Dr. Seussian trees takes a very long time.
“Because these trees are so big and they grow so slowly, it can take hundreds of years for a tree to mature,” Lauretig said. “We say they grow an inch a year, and in a wet year it might grow 5 inches or a foot, but in a dry year it might not grow at all.”
At a recent rally near the park, Curt Sauer, the former park superintendent who retired in 2010, agreed.
“What’s happened to our park in the last 34 days is irreparable for the next 200 to 300 years,” he told the crowd, according to The Desert Sun, a local newspaper. Liam Stack