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)


‘Touch the sun’: NASA spacecraft hurtles toward our star

Updated 13 August 2018
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‘Touch the sun’: NASA spacecraft hurtles toward our star

CAPE CANAVERAL, Florida: Embarking on a mission that scientists have been dreaming of since the Sputnik era, a NASA spacecraft hurtled Sunday toward the sun on a quest to unlock some of its mysteries by getting closer than any object sent before.
If all goes well, the Parker Solar Probe will fly straight through the wispy edges of the sun’s corona, or outer atmosphere, in November. In the years ahead, it will gradually get within 3.8 million miles (6 million kilometers) of the surface, its instruments protected from the extreme heat and radiation by a revolutionary new carbon heat shield and other high-tech wizardry.
Altogether, the Parker probe will make 24 close approaches to our star during the seven-year, $1.5 billion journey.
“Wow, here we go. We’re in for some learning over the next several years,” said Eugene Parker, the 91-year-old astrophysicist for whom the spacecraft is named.
It was Parker who accurately theorized 60 years ago the existence of solar wind — the supersonic stream of charged particles blasting off the sun and coursing through space, sometimes wreaking havoc on electrical systems on Earth.
This is the first time NASA has named a spacecraft after a living person.

As Parker and thousands of others watched, a Delta IV Heavy rocket carried the probe aloft, thundering into the clear, star-studded sky on three pillars of fire that lit up the middle-of-the-night darkness.
NASA needed the mighty 23-story rocket, plus a third stage, to get the Parker probe — the size of a small car and well under a ton — racing toward the sun, 93 million miles (150 million kilometers) from Earth.
A Saturday morning launch attempt was foiled by last-minute technical trouble. But Sunday gave way to complete success.
It was the first rocket launch ever witnessed by Parker, a retired University of Chicago professor. He said it was like looking at photos of the Taj Mahal for years and then beholding the real thing in India.
“I really have to turn from biting my nails in getting it launched, to thinking about all the interesting things which I don’t know yet and which will be made clear, I assume, over the next five or six or seven years,” Parker said on NASA TV.
Among the mysteries scientists hope to solve: Why is the corona hundreds of times hotter than the surface, which is 10,000 degrees Fahrenheit (5,500 degrees Celsius)? And why is the sun’s atmosphere continually expanding and accelerating, as Parker theorized in 1958?
“The only way we can do that is to finally go up and touch the sun,” said project scientist Nicola Fox of Johns Hopkins University. “We’ve looked at it. We’ve studied it from missions that are close in, even as close as the planet Mercury. But we have to go there.”
A better understanding of the sun’s life-giving and sometimes violent nature could also enable earthlings to better protect satellites and astronauts in orbit, along with the power grids so vital to today’s technology-dependent society, said Thomas Zurbuchen, NASA’s science mission chief.
Parker, the probe, will start shattering records this fall. On its very first brush with the sun, it will come within 15.5 million miles (25 million kilometers), easily beating the current record of 27 million miles (43 million kilometers) set by NASA’s Helios 2 spacecraft in 1976.
By the time Parker gets to its 22nd, 23rd and 24th orbits of the sun in 2024 and 2025, it will be even deeper into the corona and traveling at a record 430,000 mph (690,000 kilometers per hour). Nothing from planet Earth has ever gone that fast.
Even Fox has difficulty comprehending the mission’s derring-do.
“To me, it’s still mind-blowing,” she said. “Even I still go, ‘Really? We’re doing that?’“
The 8-foot (2.4-meter) heat shield will serve as an umbrella that will shade the spacecraft’s scientific instruments, with on-board sensors adjusting the protective cover as necessary so that nothing gets fried.
A mission to get up close and personal with our star has been on NASA’s books since 1958. The trick was making the spacecraft compact and light enough to travel at incredible speeds and durable enough to withstand the punishing environment.
“We’ve had to wait so long for our technology to catch up with our dreams,” Fox said.