The darkening of the sun’s rays could alleviate climate impacts in Africa

Reducing the sun’s heat by a notch by injecting billions of shiny particles of sulfur dioxide into the stratosphere could reduce devastating drought in parts of Africa, new peer-reviewed research reported.

This form of solar radiation management would reduce the risk of another “Day Zero” drought in Cape Town, South Africa, a city of 3.7 million that ran out of water in 2017, by up to 90%. , according to a study published last week in Environmental research letters.

Global warming to date – just over one degree Celsius since the mid-19th century – increases the likelihood of such droughts by a factor of three, previous research has shown.

Allowing temperatures to rise another degree to 2 ° C above pre-industrial levels would triple the risk again.

The 2015 Paris climate treaty, signed by virtually every nation in the world, calls for limiting global warming to “well below” 2 ° C, a target many experts fear is rapidly slipping out of our reach.

As the likelihood of global warming exceeding these limits increases, scientists and policy makers are seriously examining “geoengineering” schemes to cool the planet that not long ago were rejected as dangerous science fiction.

“People working on climate change are realizing that if cutting emissions don’t prove enough to limit warming to 2 ° C, blocking some sunlight could be our only hope of achieving this goal. “Andy Parker, project director for the Solar Radiation Management Governance Initiative, told AFP.

A risk in any case

“It’s not a pleasant thought, but we may have to decide if it is more risky to reflect sunlight, or if it is more risky to exceed the 2 ° C threshold.”

Cape Town’s ‘Day Zero’ drought study is one of a dozen grants from the Parker organization, which promotes both research into the potential impact of solar radiation management (SRM) on the developing world, as well as work of the scientists of these regions.

“Developing countries are the most sensitive to climate change and are very underrepresented in SRM research,” he said over the phone.

The SRM Governance Initiative takes no position on the merits of solar radiation management (SRM) and is funded entirely by non-industrial philanthropy.

“SRM has the potential to be very useful or totally disastrous, no one knows at this stage,” Parker said. “We need more information to make this decision.”

In the Cape Town study, an international team led by Romaric Odoulami found that blocking a small amount of solar radiation with reflective aerosols could keep global temperatures at 2020 levels.

Compared to the “worst case” scenario in which humanity continues without decreasing carbon emissions, SRM would reduce the risk of a “Day Zero” drought along the southwestern tip of South Africa by 90% by 2100.

Another recent article in the series, co-written by scientists in Benin, found that the technology could reduce climate change disruptions to rainfall in West Africa as well.

One technique involves injecting reflective particles into the stratosphere with balloons, airplanes, or even through giant tubes.

“Termination shock”

But even if it works as expected in one region, SRM could have unforeseen consequences in another, such as the interruption of monsoon rains on which so much agriculture in tropical regions depends.

“Our findings highlight that while the approach may be useful for drought risk in Cape Town, it could have negative consequences in other parts of Africa,” Odoulami noted.

The researchers also warn of “termination shock,” a sudden warming if the system fails.

And the technology would do nothing to stop the continued accumulation of atmospheric CO2₂, which is literally changing the chemistry of the ocean.

Scientists have long known that injecting large amounts of reflective particles into the upper atmosphere could cool the planet.

Nature sometimes does the same: debris from the 1991 eruption of Mount Pinatubo in the Philippines has lowered the average temperature of the earth’s surface for more than a year.

Sixty-six million years ago, a ten-kilometer-wide asteroid attack raised so much debris that it wiped out terrestrial dinosaurs built for steamy tropical climates.

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© 2020 AFP