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)


‘Key issues unresolved’, UN chief warns climate talks

Updated 28 min 55 sec ago
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‘Key issues unresolved’, UN chief warns climate talks

KATOWICE, Poland: “Key political issues” deadlocking UN climate talks “remain unresolved,” UN Secretary-General Antonio Guterres warned Wednesday after an unscheduled stop at the troubled negotiations in Poland.
The fight against climate change is a “matter of life and death today,” he told ministers and delegates at the 195-nation UN forum tasked with beating back the threat of global warming, barely 48 hours before the meet in the coal town of Katowice was set to adjourn.
The two-week talks are tasked with breathing life into the 2015 Paris Agreement, which vows to cap global warming at “well under” two degrees Celsius (3.6 degrees Fahrenheit) and funnel hundreds of billions of dollars to poor countries already feeling the sting of deadly storms, heatwaves and droughts made worse by climate change.
But efforts to elaborate a “rule book” for the Paris pact and to boost the carbon-cutting pledges of all nations have run aground, even as a barrage of scientific reports have warned that only immediate and radical measures can avert catastrophic climate impacts.
“The eyes of the world are upon us,” said Guterres, who had not planned to return to the talks after addressing the opening plenary 10 days ago.
“To waste this opportunity would compromise our last best chance to stop runaway climate change,” he said.
“It would not only be immoral, it would be suicidal.”
A major report called for by the UN climate body concluded in October that Earth’s rise in temperature must be capped even lower — at 1.5C — to avoid the danger of runaway warming.
But several countries at the talks, led by the United States and Saudi Arabia, have blocked efforts to endorse the report, which many developing countries see as essential.
“The IPCC report on 1.5C is the basis for all future action, on what we need to do,” Vanuatu Foreign Minister Ralph Regenvanu told AFP.
Endorsing the report’s findings at the conclusion of the UN forum “is a red line issue for us.”