Bill Gates backs bid to cool Earth with chalk dust
A large balloon will be released in Sweden this summer near the Arctic town of Kiruna. As it climbs to an altitude of 12 miles it will cross a historic threshold: the first serious attempt to explore whether global warming could be kept in check by dimming the sun.
The balloon will drop particles of calcium carbonate — chalk dust, essentially — to see if releasing them into the stratosphere could eventually deflect a portion of the sun’s energy and lower temperatures on Earth.
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