Dimming sunlight to slow global warming may harm crop yields, says study

This photograph taken on July 25, 2018, shows cyclists riding past a fountain in a 'green corridor' around Garibaldi Street in Lyon, which have been made to fight against global warming. Scientists on Wednesday said similar remedies are needed because spraying a veil of sun-dimming chemicals high above the Earth to slow global warming could harm crop yields in an unintended side-effect of turning down the heat. (AFP / JEAN-PHILIPPE KSIAZEK)
Updated 08 August 2018
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Dimming sunlight to slow global warming may harm crop yields, says study

  • Climate geoengineering may harm yields even as turns down heat
  • Man-made chemical sunshade may have little net benefit for crops

OSLO, Norway: Spraying a veil of sun-dimming chemicals high above the Earth to slow global warming could harm crop yields in an unintended side-effect of turning down the heat, US scientists said on Wednesday.
Some researchers say a man-made sunshade, perhaps sulfur dioxide released high in the atmosphere, could limit rising temperatures and the after-effects like the wildfires that have ravaged California and Greece this summer.
But a US scientific team found that big volcanic eruptions, such as Mount Pinatubo in the Philippines in 1991 and El Chichon in Mexico in 1982, cut yields of wheat, soy and rice after spewing sun-blocking ash that blew around the world.
Pinatubo’s eruption, for instance, reduced sunlight by 2.5 percent, cooled the planet by about 0.5 degree Celsius (0.9 Fahrenheit), and disrupted rainfall patterns, they wrote in the journal Nature.
And the study said any future “geoengineering” modelled on volcanoes would have scant benefits for crops, which need light to grow. Less sunlight would reduce yields even though the plants would do better in less sweltering temperatures.
“If we think of geoengineering as an experimental surgery, our findings suggest that the side effects of the treatment are just as bad as the original disease,” author Jonathan Proctor of the University of California, Berkeley, told a telephone news conference.
Co-author Solomon Hsiang, also of the University of California, Berkeley, said the findings were a surprise after some previous research suggested plants might grow better with hazier sunshine, especially crops in the shade.
The new study “doesn’t necessarily mean we should simply rule out these (geoengineering) technologies,” he said. Governments could encourage farmers to grow more shade-tolerant crops if geoengineering were ever deployed.
And interest in geoengineering as a possible climate short-cut may rise because governments are not on track to limit global warming to goals set in the 2015 Paris climate agreement to avert floods, heat waves and rising seas.
A study on Monday said the world is at risk of entering an irreversible “hothouse” state with far higher temperatures than now, even if governments meet goals set in Paris.
But many are skeptical of geoengineering.
Janos Pasztor, head of the Carnegie Climate Geoengineering Governance Initiative, welcomed Wednesday’s study as a step to understand the risks and benefits of geoengineering, which could affect everything from human health to life in the oceans.
“We need to move away from the stigma about not even being able to talk about any geoengineering options,” he told Reuters.
So far, most geoengineering experiments have been in laboratories. In the United States, Harvard University’s Solar Geoengineering Research Programme plans a tiny outdoor experiment next year in the upper atmosphere. (Reporting By Alister Doyle, editing by Larry King)


NASA probe detects likely ‘marsquake’ — an interplanetary first

A life-size model of the spaceship Insight, NASA's first robotic lander dedicated to studying the deep interior of Mars, is shown at Jet Propulsion Laboratory (JPL) in Pasadena, California, U.S. November 26, 2018. (REUTERS)
Updated 24 April 2019
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NASA probe detects likely ‘marsquake’ — an interplanetary first

  • A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said

CALIFORNIA: NASA’s robotic probe InSight has detected and measured what scientists believe to be a “marsquake,” marking the first time a likely seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory in California reported on Tuesday.
The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.
The faint rumble characterized by JPL scientists as a likely marsquake, roughly equal to a 2.5 magnitude earthquake, was recorded on April 6 — the lander’s 128th Martian day, or sol.
It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.
“We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology,” InSight principal investigator Bruce Banerdt said in a news release.
Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.
“The high frequency level and broad band is very similar to what we get from a rupture process. So we are very confident that this is a marsquake,” Philippe Lognonné, a geophysics and planetary science professor at University Paris Diderot in France and lead researcher for InSight’s seismometer, said in an email.
Still, a tremor so faint in Southern California would be virtually lost among the dozens of small seismic crackles that occur there every day.
“Our informed guesswork is that this a very small event that’s relatively close, maybe from 50 to 100 kilometers away” from the lander, Banerdt told Reuters by telephone.
A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said.
 
The size and duration of the marsquake also fit the profile of some of the thousands of moonquakes detected on the lunar surface between 1969 and 1977 by seismometers installed there by NASA’s Apollo missions, said Lori Glaze, planetary science division director at NASA headquarters in Washington.
The lunar and Martian surfaces are extremely quiet compared with Earth, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.
Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.
Three other apparent seismic signals were picked up by InSight on March 14, April 10 and April 11 but were even smaller and more ambiguous in origin, leaving scientists less certain they were actual marsquakes.
Lognonné said he expected InSight to eventually detect quakes 50 to 100 times larger than the April 6 tremor.