What it's about:
Climate scientists are tracking an erupting volcano on the Indonesian holiday island of Bali for clues about a possible short-cut to curb global warming by injecting sun-dimming chemicals high above the Earth.
As volcanoes erupt, the ash and smoke ejected into the atmosphere, if enough, can cool world temperatures.
Volcanoes are emerging as natural laboratories to mimic "geo-engineering", the idea that governments could deliberately add a veil of sulphur dioxide high above the planet as an artificial sunshade to curb man-made global warming.
Satellite measurements of eruptions have only recently become precise enough to exploit volcanoes as models for geo-engineering.
Why it's noteworthy:
Governments agree they should focus most on cutting greenhouse gas emissions under the 2015 Paris Agreement, rather than on science-fiction-like fixes to limit temperatures blamed for causing more heatwaves, floods and rising sea levels.
But current policies put the world on track to overshoot the Paris goal of limiting rising temperatures to "well below" two degrees Celsius (3.6 Fahrenheit) above pre-industrial times. And so the pressure is on to find new ways to curb climate change as quickly as possible.
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