Artificially cooling planet may pose threat to plants

ROME: Spraying chemicals into the earth’s upper atmosphere to reflect more sunlight away from the planet could be one means of coping with runaway climate change, some scientists say.

But employing the controversial “geoengineering” technique carries a range of risks - including that if such spraying was unexpectedly stopped, a rapid surge in heat on the planet would have ‘devastating’ effects on plants and animals, according to a study published Monday.

“If geoengineering ever stopped abruptly, it would be devastating. So you would have to be sure that it could be stopped gradually, and it is easy to think of scenarios that would prevent that”, said co-author Alan Robock of the Department of Environmental Sciences at Rutgers University-New Brunswick. Those might include war, a terrorist attack on facilities that carry out the spraying or political changes of heart, the study noted. “Imagine large droughts or floods around the world that could be blamed on geoengineering, and demands that it stop. Can we ever risk that?” the climate scientist added.

Research into “geoengineering” - technologies that could potentially deal with runaway climate change by artifically modifying how reflective the earth is, or sucking excess carbon dioxide out of the atmosphere - is on the upswing as the world edges closer to moving beyond what are seen as relatively safe levels of climate change.

Under the Paris agreement on climate change, countries have pledged to keep global warming to well below 2 degrees Celsius above industrial levels, with an aim of 1.5 degrees. But unless national plans to curb emissions are ramped up quickly, the Earth is expected to warm by at least 3 degrees Celsius by the end of the century - a level expected to melt much of the world´s ice and spur worsening crop failures, extreme weather and sea level rise.

The earth has already warmed more than 1 degree Celsius above pre-industrial levels, and this warming has been blamed for last year’s devastating hurricanes, droughts and floods. Spraying sulphur dioxide and other particles into the planet´s upper atmosphere would create a cloud of sulphuric acid that reflects some of the sun rays, cooling the planet, researchers say.