Jun 2, 2016
The cooling effect of pollution may have been exaggerated.
Fossil fuel burning spews sulfuric acid into the air, where it can form airborne particles that seed clouds and cool Earth’s climate. But that’s not the only way these airborne particles can form, three new studies suggest. Tree vapors can turn into cooling airborne particles, too.
The discovery means these particles were more abundant before the Industrial Revolution than previously thought. Climate scientists have therefore overestimated cooling caused by air pollution, says atmospheric chemist Urs Baltensperger, who coauthored the three studies.
Simulating unpolluted air in a cloud chamber, Baltensperger and colleagues created microscopic particles from vapors released by trees. In the real world, cosmic rays whizzing into the atmosphere foster the development of these particles, the researchers propose in the May 26 Nature. Once formed, the particles can grow large enough to form the heart of cloud droplets, the researchers show in a second paper in Nature. After sniffing the air over the Swiss Alps, some of the same researchers report in the May 27Science the discovery of the particles in the wild.
“These particles don’t just form in the laboratory, but also by Mother Nature,” says Baltensperger, of the Paul Scherrer Institute in Villigen, Switzerland.
Airborne particles, called aerosols, are microscopic bundles of molecules. Some aerosols start fully formed, such as dust and salts from sea spray, while others assemble from molecules in the atmosphere.
Since the 1970s, scientists have suspected that sulfuric acid is a mandatory ingredient for aerosols assembled in the air. Sulfuric acid molecules react with other molecules to form clusters that, if they grow large enough, can become stable. Human activities such as coal burning have boosted sulfuric acid concentrations in the atmosphere, subsequently boosting the abundance of aerosols that seed clouds and reflect sunlight like miniature disco balls. That aerosol boost partially offsets warming from greenhouse gases.
A cloud chamber at the CERN laboratory near Geneva allowed Baltensperger and his collaborators to simulate the atmosphere when sulfuric acid was scarce. The researchers added alpha-pinene, the organic vapor that gives pine trees their characteristic smell, to pristine air and watched for growing aerosols. Previous, though inconclusive, work suggested that the pine vapors might form aerosols.
Alpha-pinene molecules reacted with ozone in the air and formed molecules that reacted and bundled together to form aerosols, the researchers observed. The researchers added an extra layer of realism by using one of CERN’s particle beams to mimic ions from the cosmic rays bombarding Earth’s atmosphere. The “rays” led to the formation of as many as 100 times the number of aerosols. The added ions help stabilize the growing aerosols, the researchers propose.
Further testing showed that the newborn aerosols can rapidly grow from around 2 nanometers wide — roughly the diameter of a DNA helix — to 80 nanometers across, large enough to seed cloud droplets.
At a research station high in the Swiss Alps, researchers observed aerosol formation during atmospheric conditions with low sulfuric acid concentrations and abundant molecules akin to alpha-pinene. The researchers couldn’t confirm the rapid growth seen in the lab, though.
Quantifying the overall climate influence of fossil fuel burning in light of the new discovery will be tricky, says Renyi Zhang, an atmospheric chemist at Texas A&M University in College Station. “Atmospheric processes are complex,” he says. “They had a pure setup, but in reality the atmosphere is loaded with chemicals. It’s hard to draw direct conclusions at this point.”
For the first time, a US patient has been infected with bacteria resistant to an antibiotic used as a last resort, scientists said Thursday.
The patient, a 49-year-old woman in Pennsylvania, has recovered but health officials fear that if the resistance spreads to other bacteria, the country may soon see supergerms impervious to all known antibiotics.
“It is the end of the road for antibiotics unless we act urgently,” Dr Tom Frieden, director of the Centers for Disease Control and Prevention (CDC), said in Washington.
Other countries have already seen multidrug-resistant superbugs that no antibiotic can fight. So far, the US has not. But this sets the stage for that development, CDC officials said.
The woman had gone to a military clinic in Pennsylvania in April and was treated for a urinary tract infection. Initial tests found she was infected with E coli bacteria, a common variety of germ seen in the gut that often makes its way to the bladder.
But the tests showed this E coli was resistant to antibiotics commonly used first for such infections. She was successfully treated with another kind of antibiotic.
But while she has recovered, further testing completed in the last week confirmed the E coli was carrying a gene for resistance against the drug colistin.
Colistin is an old antibiotic. By the 1970s, doctors had mostly stopped using it because of its harsh side effects. But it was brought back as other antibiotics began losing their effectiveness.
It is used against hard-to-treat bacteria that resist one of the last lines of defence, antibiotics called carbapenems. If those germs pick up the colistin-resistance gene, doctors may be out of treatment options, health officials say.
“This is another piece of a really nasty puzzle that we didn’t want to see here,” said Dr Beth Bell, who oversees CDC’s emerging infectious diseases programs.
The CDC is working with Pennsylvania health officials to interview the woman and her family to try to figure out how she might have picked up the strain. The woman had not travelled outside the country recently, officials said.
The colistin-resistant gene has been seen in animals and people in China, Europe and Canada. Federal officials said on Thursday that colistin-resistant E coli has also been found in a pig in the US, but there was nothing to link the finding to the Pennsylvania case.
Researchers at Walter Reed national military medical center, who did the confirmatory tests, reported on the Pennsylvania case on Thursday in a journal of the American Society of Microbiology.
The theory of panspermia posits that life on Earth may have been seeded by meteorites and comets carrying hardy spores of microorganisms. This possibility is what makes studying comets such an exciting area of research for scientists seeking to understand the origin of life on our planet and the evolution of the solar system.
Now, a new study, based on data gathered by instruments on board the European Space Agency’s (ESA) Rosetta spacecraft — which is currently following the comet 67P/Churyumov-Gerasimenko — further bolsters the possibility that the building blocks of life on Earth may have come from outer space.
Researchers have detected the amino acid glycine, commonly found in proteins, and phosphorus, a key component of DNA and cell membranes, in the coma of the comet.
“This is the first unambiguous detection of glycine at a comet,” lead author Kathrin Altwegg, principal investigator of the ROSINA instrument that made the measurements, said in a statement. “At the same time, we also detected certain other organic molecules that can be precursors to glycine, hinting at the possible ways in which it may have formed.”
A coma is the fuzzy, nebulous envelope of dust and gas that usually surrounds a comet’s nucleus. The shape and size of the coma vary depending on the comet’s composition and its distance from the sun.
According to the study, “the presence of glycine, phosphorus, and a multitude of organic molecules, including hydrogen sulfide and hydrogen cyanide ... supports the idea that comets delivered key molecules for prebiotic chemistry throughout the solar system and, in particular, to the early Earth, drastically increasing the concentration of life-related chemicals by impact on a closed water body.”
Scientists believe that life on Earth originated nearly 3.7 billion years ago, bubbling out of a “primordial soup” rich in organic compounds. While we now have a clear picture of the evolution of life from its most ancient single-celled form to the present-day complexity we see around us, what is less clear is how the seeds of life came to exist on Earth.
“There is still a lot of uncertainty regarding the chemistry on early Earth and there is of course a huge evolutionary gap to fill between the delivery of these ingredients via cometary impacts and life taking hold,” co-author Hervé Cottin said in the statement. “But the important point is that comets have not really changed in 4.5 billion years — they grant us direct access to some of the ingredients that likely ended up in the prebiotic soup that eventually resulted in the origin of life on Earth.”
With the discovery of glycine — the simplest of all amino acids — and phosphorus, the theory of panspermia has been lent further credence.
“Demonstrating that comets are reservoirs of primitive material in the Solar System and vessels that could have transported these vital ingredients to Earth, is one of the key goals of the Rosetta mission, and we are delighted with this result,” Matt Taylor, ESA's Rosetta project scientist, said in the statement.
Stephen Hawking has said that he fails to understand the popularity of Donald Trump, the presumptive US Republican presidential candidate.
ITV’s Good Morning Britain asked the man who has widened the world’s understanding of time, space, stars, galaxies and black holes if he could explain the popular appeal of the billionaire tycoon.
Hawking, perhaps the world’s most famous living scientist and the author of one of the world’s best-selling books, replied: “I can’t. He’s a demagogue who seems to appeal to the lowest common denominator.”
He also ventured once again into political issues, appealing to British voters to back the remain campaign in the EU referendum on 23 June – not just for economic and security reasons, but for the sake of science as well. In March, he pronounced the prospect of Brexit “a disaster” for science.
“Gone are the days when we could stand on our own, against the world,” he said on the television breakfast show. “We need to be part of a larger group of nations, both for our security and our trade. The possibility of our leaving the EU has already led to a sharp fall in the pound, because the markets judge that it will damage our economy.”
Hawking also addressed the biggest concern of many: immigration.
“There are two obvious reasons why we should stay in. The first is that it promotes the mobility of people. Students can come here from EU countries to study, and our students can go to other EU universities. More importantly, at the level of research, the exchange of people enables skills to transfer more quickly, and brings new people with different ideas, derived from their different backgrounds,” he said.
“The other reason is financial. The European Research Council has given large grants to UK institutions, either to foster or promote exchanges.”
The Cambridge scientist, like Isaac Newton 350 years ago, was once Lucasian professor of mathematics at Cambridge University. Hawking was diagnosed with motor neurone disease in 1963 and given two years to live. Instead he wrote A Brief History of Time and became one of the world’s bestselling authors, and one of the world’s most instantly recognised scientists: he has appeared in his wheelchair in both Star Trek and the Simpsons.
Because he communicates fairly slowly, using a computerised voice that pronounces words he must spell out using assistive technology, all his opinions must be counted as carefully considered.
And over the years, he has been unapologetically opinionated, not just on behalf of his fellow scientists, and on behalf of Britain’s disabled, but on wider matters: he joined an academic boycott in protest against Israeli treatment of Palestinians; he backed a recent $100m project to accelerate a tiny spacecraft to a fifth of the speed of light and send it to the nearest star system; he has spoken in favour of assisted suicide for the terminally ill; he has spoken up for atheism; he has made ominous pronouncements about artificial intelligence research; and he has even invited the fans of One Direction to imagine an alternative universe in which Zayn Malik was still with the band.
His latest return to referendum politics is less of a surprise: many of Britain’s most senior scientists have backed the remain campaign.
The exit enthusiasts however, are not swayed.
“The EU has been bad for science – increasing costs and bureaucracy. The clinical trials directive, for example, acted to double the cost of cancer research – as leading scientists and medical practitioners have acknowledged,” said the Vote Leave chief executive, Matthew Elliott.
“In the internet age, it is patently ridiculous to suggest that the referendum will have an impact on the exchange of information between scientists. And with our world class universities, the calibre of scientists wanting to study here is unlikely to do anything except grow.
“We give more money to the EU than we get back – meaning we could spend more on science if we vote to leave.”
This episode of the Blue Streak Science Podcast comes to you from Sydney, Australia; and Santa Rosa, California.