Printable tags turn everyday objects into smart, connected devices

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Engineers have developed printable metal tags that could be attached to everyday objects and turn them into “smart” Internet of Things devices.

The metal tags are made from patterns of copper foil printed onto thin, flexible, paper-like substrates and are made to reflect WiFi signals. The tags work essentially like “mirrors” that reflect radio signals from a WiFi router. When a user’s finger touches these mirrors, it disturbs the reflected WiFi signals in such a way that can be remotely sensed by a WiFi receiver, like a smartphone.

The tags can be tacked onto plain objects that people touch and interact with every day, like water bottles, walls or doors. These plain objects then essentially become smart, connected devices that can signal a WiFi device whenever a user interacts with them. The tags can also be fashioned into thin keypads or smart home control panels that can be used to remotely operate WiFi-connected speakers, smart lights and other Internet of Things appliances.

“Our vision is to expand the Internet of Things to go beyond just connecting smartphones, smartwatches and other high-end devices,” said senior author Xinyu Zhang, a professor of electrical and computer engineering at the UC San Diego Jacobs School of Engineering and member of the Center for Wireless Communications at UC San Diego. “We’re developing low-cost, battery-free, chipless, printable sensors that can include everyday objects as part of the Internet of Things.”

Zhang’s team named the technology “LiveTag.” These metal tags are designed to only reflect specific signals within in the WiFi frequency range. By changing the type of material they’re made of and the pattern in which they’re printed, the researchers can redesign the tags to reflect either Bluetooth, LTE or cellular signals.

The tags have no batteries, silicon chips, or any discrete electronic components, so they require hardly any maintenance — no batteries to change, no circuits to fix.

The team presented their work at the recent USENIX Symposium on Networked Systems Design and Implementation Conference.

Smart tagging

As a proof of concept, the researchers used LiveTag to create a paper-thin music player controller complete with a play/pause button, next track button and sliding bar for tuning volume. The buttons and sliding bar each consist of at least one metal tag so touching any of them sends signals to a WiFi device. The researchers have so far only tested the LiveTag music player controller to remotely trigger a WiFi receiver, but they envision that it would be able to remotely control WiFi-connected music players or speakers when attached to a wall, couch armrest, clothes, or other ordinary surface.

The researchers also adapted LiveTag as a hydration monitor. They attached it to a plastic water bottle and showed that it could be used to track a user’s water intake by monitoring the water level in the bottle. The water inside affects the tag’s response in the same way a finger touch would — as long as the bottle is not made of metal, which would block the signal. The tag has multiple resonators that each get detuned at a specific water level. The researchers imagine that the tag could be used to deliver reminders to a user’s smartphone to prevent dehydration.

Future applications

On a broader scope, Zhang envisions using LiveTag technology to track human interaction with everyday objects. For example, LiveTag could potentially be used as an inexpensive way to assess the recovery of patients who have suffered from stroke.

“When patients return home, they could use this technology to provide data on their motor activity based on how they interact with everyday objects at home — whether they are opening or closing doors in a normal way, or if they are able to pick up bottles of water, for example. The amount, intensity and frequency of their activities could be logged and sent to their doctors to evaluate their recovery,” said Zhang. “And this can all be done in the comfort of their own homes rather than having to keep going back to the clinic for frequent motor activity testing,” he added.

Another example is tagging products at retail stores and assessing customer interest based on which products they touch. Rather than use cameras, stores could use LiveTag as an alternative that offers customers more privacy.

Next steps

The researchers note several limitations of the technology. LiveTag currently cannot work with a WiFi receiver further than one meter (three feet) away, so researchers are working on improving the tag sensitivity and detection range.

Laziness helped lead to extinction of Homo erectus

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New archaeological research from The Australian National University (ANU) has found that Homo erectus, an extinct species of primitive humans, went extinct in part because they were ‘lazy’.

An archaeological excavation of ancient human populations in the Arabian Peninsula during the Early Stone Age, found that Homo erectus used ‘least-effort strategies’ for tool making and collecting resources.

This ‘laziness’ paired with an inability to adapt to a changing climate likely played a role in the species going extinct.

“They really don’t seem to have been pushing themselves.”

“I don’t get the sense they were explorers looking over the horizon. They didn’t have that same sense of wonder that we have.”

Dr Shipton said this was evident in the way the species made their stone tools and collected resources.

“To make their stone tools they would use whatever rocks they could find lying around their camp, which were mostly of comparatively low quality to what later stone tool makers used.”

“At the site we looked at there was a big rocky outcrop of quality stone just a short distance away up a small hill.

“But rather than walk up the hill they would just use whatever bits had rolled down and were lying at the bottom.

“When we looked at the rocky outcrop there were no signs of any activity, no artefacts and no quarrying of the stone.

“They knew it was there, but because they had enough adequate resources they seem to have thought, ‘why bother?’.”

This is in contrast to the stone tool makers of later periods, including early Homo sapiens and Neanderthals, who were climbing mountains to find good quality stone and transporting it over long distances.

Dr Shipton said a failure to progress technologically, as their environment dried out into a desert, also contributed to the population’s demise.

“Not only were they lazy, but they were also very conservative,” Dr Shipton said.

“The sediment samples showed the environment around them was changing, but they were doing the exact same things with their tools.

“There was no progression at all, and their tools are never very far from these now dry river beds. I think in the end the environment just got too dry for them.”

The excavation and survey work was undertaken in 2014 at the site of Saffaqah near Dawadmi in central Saudi Arabia.

Compounds in ‘monster’ radish could help tame cardiovascular disease

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Step aside carrots, onions and broccoli. The newest heart-healthy vegetable could be a gigantic, record-setting radish. scientists report that compounds found in the Sakurajima Daikon, or “monster,” radish could help protect coronary blood vessels and potentially prevent heart disease and stroke. The finding could lead to the discovery of similar substances in other vegetables and perhaps lead to new drug treatments.

Grown for centuries in Japan, the Sakurajima Daikon is one of the Earth’s most massive vegetables. In 2003, the Guinness Book of World Records certified a Sakurajima weighing nearly 69 pounds as the world’s heaviest radish. Radishes are good sources of antioxidants and reportedly can reduce high blood pressure and the threat of clots, a pair of risk factors for heart attack and stroke. But to date, no studies have directly compared the heart-health benefits of the Sakurajima Daikon to other radishes. To address this knowledge gap, Katsuko Kajiya and colleagues sought to find out what effects this radish would have on nitric oxide production, a key regulator of coronary blood vessel function, and to determine its underlying mechanisms.

The researchers exposed human and pig vascular endothelial cells to extracts from Sakurajima Daikon and smaller radishes. Using fluorescence microscopy and other analytical techniques, the research team found the Sakurajima Daikon radish induced more nitric oxide production in these vascular cells than a smaller Japanese radish. They also identified trigonelline, a plant hormone, as the active component in Sakurajima Daikon that appears to promote a cascade of changes in coronary blood vessels resulting improved nitric oxide production.

Study illuminates genes behind beautiful ‘glow’ of Bermuda fireworms

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 glow are unique among bioluminescent animals and entirely unlike those seen in fireflies. The study also examines genes associated with some of the dramatic — and reversible — changes that happen to the fireworms during reproduction.

The beautiful bioluminescence of the Bermuda fireworm , which lives throughout the Caribbean, was first documented in 1492 by Christopher Columbus and his crew just before landing in the Americas. The observations described the lights as “looking like the flame of a small candle alternately raised and lowered.”

The phenomenon went unexplained until the 1930s, when scientists matched the historic description with the unusual and precisely timed mating behavior of fireworms. During summer and autumn, beginning at 22 minutes after sunset on the third night after the full Moon, spawning female fireworms secrete a bright bluish-green luminescence that attracts males. “It’s like they have pocket watches,” said lead author Mercer R. Brugler, a Museum research associate and assistant professor at New York City College of Technology (City Tech).

“The female worms come up from the bottom and swim quickly in tight little circles as they glow, which looks like a field of little cerulean stars across the surface of jet black water,” said Mark Siddall, a curator in the American Museum of Natural History’s Division of Invertebrate Zoology and corresponding author of the study. “Then the males, homing in on the light of the females, come streaking up from the bottom like comets — they luminesce, too. There’s a little explosion of light as both dump their gametes in the water. It is by far the most beautiful biological display I have ever witnessed.”

To further investigate this phenomenon, Siddall, together with Brugler; Michael Tessler, a postdoctoral fellow in the Museum’s Sackler Institute for Comparative Genomics, and M. Teresa Aguado, former postdoctoral fellow in the Museum’s Sackler Institute for Comparative Genomics who is now at the Autonomous University of Madrid, analyzed the transcriptome — the full set of RNA molecules — of a dozen female fireworms from Ferry Reach in Bermuda.

Their findings support previous work showing that fireworms “glow” because of a special luciferase enzyme they produce. These enzymes are the principal drivers of bioluminescence across the tree of life, in organisms as diverse as copepods, fungi, and jellyfish. However, the luciferases found in Bermuda fireworms and their relatives are distinct from those found in any other organism to date.

” The work also took a close look at genes related to the precise reproductive timing of the fireworms, as well as the changes that take place in the animals’ bodies just prior to swarming events. These changes include the enlargement and pigmentation of the worms’ four eyes and the modification of the nephridia — an organ similar to the kidney in vertebrates — to store and release gametes.

Marine mammals lack functional gene to defend against popular pesticide

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As marine mammals evolved to make water their primary habitat, they lost the ability to make a protein that defends humans and other land-dwelling mammals from the neurotoxic effects of a popular human-made pesticide.

The implications of this discovery, announced today in Science, led researchers to call for monitoring our waterways to learn more about the impact of pesticides and agricultural run-off on marine mammals, such as dolphins, manatees, seals and whales. The research also may shed further light on the function of the gene encoding this protein in humans.

“We need to determine if marine mammals are, indeed, at an elevated risk of serious neurological damage from these pesticides because they biologically lack the ability to break them down, or if they’ve somehow adapted to avoid such damage in an as-yet undiscovered way,”  associate professor in Pitt’s Department of Computational and Systems Biology, and the Pittsburgh Center for Evolutionary Biology and Medicine. “Either way, this is the kind of serendipitous finding that results from curiosity-driven scientific research. It is helping us to understand what our genes are doing and the impact the environment can have on them.”

a postdoctoral associate in his laboratory, knew from previous research by other scientists that some genes behind smelling and tasting lost their function during the evolution of marine mammals. They set out to see what other genes conserved in land-dwelling mammals had lost function in marine mammals.

By analyzing DNA sequences from five species of marine mammals and 53 species of terrestrial mammals, was the gene that best matched the pattern of losing function in marine mammals while retaining function in all terrestrial mammals. PON1 even beat out several genes responsible for smell and taste, senses that marine mammals don’t rely on much.

In humans and other terrestrial mammals, PON1 reduces cellular damage caused by unstable oxygen atoms. It also protects us from organophosphates, some of which are pesticides that kill insects — which lack PON1 — by disrupting their neurological systems.

Clark and Meyer worked with Joseph Gaspard, Ph.D., director of science and conservation at the Pittsburgh Zoo & PPG Aquarium, now a scientist emeritus at the U.S. Geological Survey’s Wetland and Aquatic Research Center, to obtain marine mammal blood samples from U.S. and international scientists and conservation biologists. Collaborators at the University of Washington reacted blood samples from several marine mammals with an organophosphate byproduct and observed what happened. The blood did not break down the organophosphate byproduct the way it does in land mammals, indicating that, unless a different biological mechanism is protecting the marine mammals, they would be susceptible to “organophosphate poisoning,” a form of poisoning that results from the buildup of chemical signals in the body, especially the brain.

In an attempt to learn why marine mammals lost PON1 function, the researchers traced back when the function was lost in three different groups of marine mammals. Whales and dolphins lost it soon after they split from their common ancestor with hippopotamuses 53 million years ago; manatees lost it after their split from their common ancestor with elephants 64 million years ago. But some seals likely lost PON1 function more recently, at most 21 million years ago and possibly in very recent times.

“The big question is, why did they lose function at PON1 in the first place?” said Meyer. “It’s hard to tell whether it was no longer necessary or whether it was preventing them from adapting to a marine environment. We know that ancient marine environments didn’t have organophosphate pesticides, so we think the loss might instead be related to PON1’s role in responding to the extreme oxidative stress generated by long periods of diving and rapid resurfacing. If we can figure out why these species don’t have functional PON1, we might learn more about the function of PON1 in human health, while also uncovering potential clues to help protect marine mammals most at risk.”

As an example of the potential real-world consequences of losing function at PON1, the researchers explain in their scientific manuscript that in Florida, “agricultural use of organophosphate pesticides is common and runoff can drain into manatee habitats. In Brevard County, where 70 percent of Atlantic Coast manatees are estimated to migrate or seasonally reside, agricultural lands frequently abut manatee protection zones and waterways.”

The scientists believe the next step is to launch a study that directly observes marine mammals during and shortly after periods of excess agricultural organophosphate run-off. Such a project would require increased monitoring of marine mammal habitats, as well as testing of tissues from deceased marine mammals for evidence of organophosphate exposure. The most recent estimate the research team could find of organophosphate levels in manatee habitats in Florida is a decade old, Clark said.

“Marine mammals, such as manatees or bottlenose dolphins, are sentinel species — the canary in the coal mine,” said Clark. “If you follow their health, it will tell you a lot about potential environmental issues that could eventually affect humans.”

Novel approach to coherent control of a three-level quantum system

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For the first time, researchers were able to study quantum interference in a three-level quantum system and thereby control the behavior of individual electron spins. To this end, they used a novel nanostructure, in which a quantum system is integrated into a nanoscale mechanical oscillator in form of a diamond cantilever. Nature Physics has published the study that was conducted at the University of Basel and the Swiss Nanoscience Institute.

The electronic spin is a fundamental quantum mechanical property intrinsic to every electron. In the quantum world, the electronic spin describes the direction of rotation of the electron around its axis which can normally occupy two so-called eigenstates commonly denoted as “up” and “down.” The quantum properties of such spins offer interesting perspectives for future technologies, for example in the form of extremely precise quantum sensors.

Combining spins with mechanical oscillators

Researchers led by Professor Patrick Maletinsky and PhD candidate Arne Barfuss from the Swiss Nanoscience Institute at the University of Basel report in Nature Physics a new method to control the spins’ quantum behavior through a mechanical system.

For their experimental study, they combined such a quantum system with a mechanical oscillator. More specifically, the researchers employed electrons trapped in so-called nitrogen-vacancy centers and embedded these spins in single-crystalline mechanical resonators made from diamond.

These nitrogen-vacancy spins are special, in that they possess not only two, but three eigenstates, which can be described as “up,” “down” and “zero.” Using the special coupling of a mechanical oscillator to the spin, they showed for the first time a complete quantum control over such a three-level system, in a way not possible before.

Controlling three quantum states

In particular, the oscillator allowed them to address all three possible transitions in the spin and to study how the resulting excitation pathways interfere with each other.

This scenario, known as “closed-contour driving,” has never been investigated so far but opens interesting fundamental and practical perspectives. For example, their experiment allowed for a breaking of time-reversal symmetry, which means that the properties of the system look fundamentally different if the direction of time is reversed than without such inversion. In this scenario, the phase of the mechanical oscillator determined whether the spin circled “clockwise” (direction of rotation up, down, zero, up) or “counter-clockwise.”

Extending coherence

This abstract concept has practical consequences for the fragile quantum states. Similar to the well-known Schrödinger’s cat, spins can be simultaneously in a superposition of two or three of the available eigenstates for a certain period, the so-called quantum coherence time.

If the three eigenstates are coupled to each other using the closed contour driving discovered here, the coherence time can be significantly extended, as the researchers were able to show. Compared to systems where only two of the three possible transitions are driven, coherence increased almost a hundredfold.

Such coherence protection is a key element for future quantum technologies and another main result of this work.

Applications for sensor technology

The work described here holds high potential for future applications. It is conceivable that the hybrid resonator-spin system could be used for the precise measurement of time-dependent signals with frequencies in the gigahertz range — for example in quantum sensing or quantum information processing. For time-dependent signals emerging from nanoscale objects, such tasks are currently very difficult to address otherwise. Here the combination of spin and an oscillating system could provide helpful, in particular also because of the demonstrated protection of spin coherence.

First particle accelerator beam measurement in six dimensions

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The first full characterization measurement of an accelerator beam in six dimensions will advance the understanding and performance of current and planned accelerators around the world.

A team of researchers led by the University of Tennessee, Knoxville conducted the measurement in a beam test facility at the Department of Energy’s Oak Ridge National Laboratory using a replica of the Spallation Neutron Source’s linear accelerator.

“Our goal is to better understand the physics of the beam so that we can improve how accelerators operate,”  group leader in ORNL’s Research Accelerator Division and UT joint faculty professor. “Part of that is related to being able to fully characterize or measure a beam in 6D space — and that’s something that, until now, has never been done.”

Six-dimensional space is like 3D space but includes three additional coordinates on the x, y, and z axes to track motion or velocity.

“Right away we saw the beam has this complex structure in 6D space that you can’t see below 5D — layers and layers of complexities that can’t be detangled,” Cousineau said. “The measurement also revealed the beam structure is directly related to the beam’s intensity, which gets more complex as the intensity increases.”

Previous attempts to fully characterize an accelerator beam fell victim to “the curse of dimensionality,” in which measurements in low dimensions become exponentially more difficult in higher dimensions. Scientists have tried to circumvent the issue by adding three 2D measurements together to create a quasi-6D representation. The UT-ORNL team notes that approach is incomplete as a measurement of the beam’s initial conditions entering the accelerator, which determine beam behavior farther down the linac.

As part of efforts to boost the power output of SNS, ORNL physicists used the beam test facility to commission the new radio frequency quadrupole, the first accelerating element located at the linac’s front-end assembly. With the infrastructure already in place, a research grant from the National Science Foundation to the University of Tennessee enabled outfitting the beam test facility with the state-of-the-art 6D measurement capability. Conducting 6D measurements in an accelerator has been limited by the need for multiple days of beam time, which can be a challenge for production accelerators.

“Because we have a replica of the linac’s front-end assembly at the beam test facility, we don’t have to worry about interrupting users’ experiment cycles at SNS. That provides us with unfettered access to perform these time-consuming measurements, which is something we wouldn’t have at other facilities,” said lead author Brandon Cathey, a UT graduate student.

“This result shows the value of combining the freedom and ingenuity of NSF-funded academic research with facilities available through the broad national laboratory complex,” said Vyacheslav Lukin, the NSF program officer who oversees the grant to the University of Tennessee. “There is no better way to introduce a new scientist — a graduate student — to the modern scientific enterprise than by allowing them to lead a first-of-a-kind research project at a facility that uniquely can dissect the particles that underpin what we know and understand about matter and energy.”

The researchers’ ultimate goal is to model the entire beam, including mitigating so-called beam halo, or beam loss — when particles travel to the outer extremes of the beam and are lost. The more immediate challenge, they say, will be finding software tools capable of analyzing the roughly 5 million data points the 6D measurement generated during the 35-hour period.

“When we proposed making a 6D measurement 15 years ago, the problems associated with the curse of dimensionality seemed insurmountable,” said ORNL physicist and coauthor Alexander Aleksandrov. “Now that we’ve succeeded, we’re sure we can improve the system to make faster, higher resolution measurements, adding an almost ubiquitous technique to the arsenal of accelerator physicists everywhere.”

Pass the salt: Study finds average consumption safe for heart health

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New research shows that for the vast majority of individuals, sodium consumption does not increase health risks except for those who eat more than five grams a day, the equivalent of 2.5 teaspoons of salt.

Fewer than five per cent of individuals in developed countries exceed that level.

The large, international study also shows that even for those individuals there is good news. Any health risk of sodium intake is virtually eliminated if people improve their diet quality by adding fruits, vegetables, dairy foods, potatoes, and other potassium rich foods.

The study followed 94,000 people, aged 35 to 70, for an average of eight years in communities from18 countries around the world and found there an associated risk of cardiovascular disease and strokes only where the average intake is greater than five grams of sodium a day.

China is the only country in their study where 80 per cent of communities have a sodium intake of more than five grams a day. In the other countries, the majority of the communities had an average sodium consumption of 3 to 5 grams a day (equivalent to 1.5 to 2.5 teaspoons of salt).

“The World Health Organization recommends consumption of less than two grams of sodium — that’s one teaspoon of salt — a day as a preventative measure against cardiovascular disease, but there is little evidence in terms of improved health outcomes that individuals ever achieve at such a low level,” said Andrew Mente, first author of the study and a PHRI researcher.

He added that the American Heart Association recommends even less — 1.5 grams of sodium a day for individuals at risk of heart disease.

“Only in the communities with the most sodium intake  those over five grams a day of sodium  which is mainly in China, did we find a direct link between sodium intake and major cardiovascular events like heart attack and stroke.

“In communities that consumed less than five grams of sodium a day, the opposite was the case. Sodium consumption was inversely associated with myocardial infarction or heart attacks and total mortality, and no increase in stroke.”

Mente added: “We found all major cardiovascular problems, including death, decreased in communities and countries where there is an increased consumption of potassium which is found in foods such as fruits, vegetables, dairy foods, potatoes and nuts and beans.”

The information for the research article came from the ongoing, international Prospective Urban Rural Epidemiology (PURE) study run by the PHRI. Mente is also an associate professor of the Department of Health Research Methods, Evidence and Impact at McMaster University.

Most previous studies relating sodium intake to heart disease and stroke were based on individual-level information, said Martin O’Donnell.

“Public health strategies should be based on best evidence. Our findings demonstrate that community-level interventions to reduce sodium intake should target communities with high sodium consumption, and should be embedded within approaches to improve overall dietary quality.

“There is no convincing evidence that people with moderate or average sodium intake need to reduce their sodium intake for prevention of heart disease and stroke.”

Blocking sunlight to cool Earth won’t reduce crop damage from global warming

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Injecting particles into the atmosphere to cool the planet and counter the warming effects of climate change would do nothing to offset the crop damage from rising global temperatures, according to a new analysis by University of California, Berkeley, researchers.

By analyzing the past effects of Earth-cooling volcanic eruptions, and the response of crops to changes in sunlight, the team concluded that any improvements in yield from cooler temperatures would be negated by lower productivity due to reduced sunlight. The findings have important implications for our understanding of solar geoengineering, one proposed method for helping humanity manage the impacts of global warming.

“Shading the planet keeps things cooler, which helps crops grow better. But plants also need sunlight to grow, so blocking sunlight can affect growth. For agriculture, the unintended impacts of solar geoengineering are equal in magnitude to the benefits,” said lead author Jonathan Proctor, a UC Berkeley doctoral candidate in the Department of Agricultural and Resource Economics. “It’s a bit like performing an experimental surgery; the side-effects of treatment appear to be as bad as the illness.”

“Unknown unknowns make everybody nervous when it comes to global policies, as they should,” said Solomon Hsiang, co-lead author of the study and Chancellor’s Associate Professor of Public Policy at UC Berkeley. “The problem in figuring out the consequences of solar geoengineering is that we can’t do a planetary-scale experiment without actually deploying the technology. The breakthrough here was realizing that we could learn something by studying the effects of giant volcanic eruptions that geoengineering tries to copy.”

Hsiang is director of UC Berkeley’s Global Policy Laboratory, where Proctor is a doctoral fellow.

Proctor and Hsiang will publish their findings online in the journal Nature on August 8.

Some people have pointed to past episodes of global cooling caused by gases emitted during massive volcanic eruptions, such as Mt. Pinatubo in the Philippines in 1991, and argued that humans could purposely inject sulfate aerosols into the upper atmosphere to artificially cool Earth and alleviate the greenhouse warming caused by increased levels of carbon dioxide. Aerosols — in this case, minute droplets of sulfuric acid — reflect a small percentage of sunlight back into space, reducing the temperature a few degrees.

“It’s like putting an umbrella over your head when you’re hot,” Proctor said. “If you put a global sunshade up, it would slow warming.”

Pinatubo, for example, injected about 20 million tons of sulfur dioxide into the atmosphere, reducing sunlight by about 2.5 percent and lowering the average global temperature by about half a degree Celsius (nearly 1 degree Fahrenheit).

The team linked maize, soy, rice and wheat production from 105 countries from 1979-2009 to global satellite observations of these aerosols to study their effect on agriculture. Pairing these results with global climate models, the team calculated that the loss of sunlight from a sulfate-based geoengineering program would cancel its intended benefits of protecting crops from damaging extreme heat.

“It’s similar to using one credit card to pay off another credit card: at the end of the day, you end up where you started without having solved the problem,” Hsiang said.

Some earlier studies suggested that aerosols might improve crop yields also by scattering sunlight and allowing more of the sun’s energy to reach interior leaves typically shaded by upper canopy leaves. This benefit of scattering appears to be weaker than previously thought.

“We are the first to use actual experimental and observational evidence to get at the total impacts that sulfate-based geoengineering might have on yields,” Proctor said. “Before I started the study, I thought the net impact of changes in sunlight would be positive, so I was quite surprised by the finding that scattering light decreases yields.”

Despite the study’s conclusions, Proctor said, “I don’t think we should necessarily write off solar geoengineering. For agriculture, it might not work that well, but there are other sectors of the economy that could potentially benefit substantially.”

Proctor and Hsiang noted that their methods could be used to investigate the impact of geoengineering on other segments of the economy, human health and the functioning of natural ecosystems.

They did not address other types of geoengineering, such as capture and storage of carbon dioxide, or issues surrounding geoengineering, such as its impact on Earth’s protective ozone layer and who gets to set Earth’s thermostat.

“Society needs to be objective about geoengineering technologies and develop a clear understanding of the potential benefits, costs and risks,” Proctor said. “At present, uncertainty about these factors dwarfs what we understand.”

The authors emphasize the need for more research into the human and ecological consequences of geoengineering, both good and bad.

“The most certain way to reduce damages to crops and, in turn, people’s livelihood and well-being, is reducing carbon emissions,” Proctor said.

“Perhaps what is most important is that we have respect for the potential scale, power and risks of geoengineering technologies,” Hsiang said. “Sunlight powers everything on the planet, so we must understand the possible outcomes if we are going to try to manage it.”

Ever-increasing CO2 levels could take us back to the tropical climate of Paleogene period

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A new study led by scientists at the University of Bristol has warned that unless we mitigate current levels of carbon dioxide emissions, Western Europe and New Zealand could revert to the hot tropical climate of the early Paleogene period — 56-48 million years ago.

As seen from the ongoing heat wave, the knock-on effects of such extreme warmth include arid land and fires as well as impacts on health and infrastructure.

The early Paleogene is a period of great interest to climate change scientists as carbon dioxide levels (around 1,000 ppmv) are similar to those predicted for the end of this century.

Dr David Naafs from the University of Bristol’s School of Earth Sciences,  “We know that the early Paleogene was characterised by a greenhouse climate with elevated carbon dioxide levels.

“Most of the existing estimates of temperatures from this period are from the ocean, not the land — what this study attempts to answer is exactly how warm it got on land during this period.”

Scientists used molecular fossils of microorganisms in ancient peat (lignite) to provide estimates of land temperature 50 million-years ago. This demonstrated that annual land temperatures in Western Europe as well as New Zealand were actually higher than previously thought — between 23 and 29 °C — this is currently 10 to 15 °C higher than current average temperatures in these areas.

These results suggest that temperatures similar to those of the current heat wave that is influencing western Europe and other regions would become the new norm by the end of this century if CO2 levels in the atmosphere continue to increase.

Professor Rich Pancost, Co-author and Director of the University of Bristol Cabot Institute, added: “Our work adds to the evidence for a very hot climate under potential end-of-century carbon dioxide levels. “Importantly, we also study how the Earth system responded to that warmth. For example, this and other hot time periods were associated with evidence for arid conditions and extreme rainfall events.”

The research team will now turn their attentions to geographical areas in lower-latitudes to see how hot land temperatures were there.

Dr Naafs said: “Did the tropics, for example, become ecological dead zones because temperatures in excess of 40 °C were too high for most form of life to survive?

“Some climate models suggest this, but we currently lack critical data.

“Our results hint at the possibility that the tropics, like the mid-latitudes, were hotter than present, but more work is needed to quantify temperatures from these regions.”