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Climate Change? Sun-Dimming Spray May Help Cool Down The Planet

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Harvard scientists experiment on a new way of reversing climate change by spraying small packets of calcium carbonate into the stratosphere. The effect will dim the skies, similar to what happens after a volcanic eruption.  ( Kayana Szymczak | Nature )

Scientists at Harvard University are planning to geoengineer the stratosphere by spraying tiny chalk particles to drastically cool the planet's temperature.

The experiment, which is slated to take place on the first half of 2019, will mimic the effects of a volcanic eruption. The chalk particles contained in a balloon that will be suspended 12 miles above Earth will deflect the sun's rays.

Mimicking Volcanic Eruption

In 1991, Mount Pinatubo in the Philippines erupted, spewing 20 million tons of sulfur dioxide into the atmosphere. The resulting haze cooled the Earth by 0.5 degrees Celsius for 18 consecutive months.

The researchers will try to emulate this volcanic event by releasing small amounts of calcium carbonate — each weighs around 100 grams. It is estimated that this effort could cool down the planet by 1.5 degrees Celsius at $10 billion a year.

The experiment is part of a larger $3-million project called Stratospheric Controlled Perturbation Experiment (SCoPEx).

"SCoPEx is the first out of the gate, and it is triggering an important conversation about what independent guidance, advice and oversight should look like," said Peter Frumhoff, chief climate scientist at the Union of Concerned Scientists in Cambridge, Massachusetts.

"Getting it done right is far more important than getting it done quickly."

Benefits Of Dimming The Sky

Scattered light caused by dimmer skies will allow the growth of rainforests. Melting of the ice sheets will slow down, and food chain will be eventually restored. Crops will receive less heat, but lower levels of sunlight could also mean stunted plant growth.

While SCoPEx appears to be an effective way of reversing global warming, the experiment is highly technical and difficult. The team needs to find sources of calcium carbonate plumes and then accurately measure each droplet to about 0.5 micrometers so it can disperse the sunlight well.

The actual balloon launch is also dependent on the wind velocity in the stratosphere. The team is most likely to fly the balloon in the spring or autumn, when winds are calmer and the plume will be easier to track.

"Operational constraints would therefore be similar to that of unpropelled balloons used for stratospheric science and astronomy," the researchers reported in their study. "This means there is a significant chance that one would not get acceptable conditions during a given season and would miss a launch opportunity."

The project is the first of its kind in solar geoengineering. Pro-environmental groups said SCoPEx deviates the focus away from the true permanent solution to the problem, which is to reduce greenhouse gas emissions. Jim Thomas, co-executive director of the ETC Group, an environmental organization in Canada, said that what SCoPEx does is pushing its boundaries as a science experiment by changing the current social norms.

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