Harvard scientists will test viability of dimming the sun

Nobody’s really rooting for a huge volcanic eruption. Ash spewing out harmful gases into the atmosphere and burying cities isn’t so great. Neither is lava swallowing and burning everything in its path. But some aspects of an eruption can be beneficial. For instance, the eruption of Mt. Pinatubo in 1991 produced enough sulfur dioxide to block some energy from the sun, lowering the global temperature by half a degree celsius for a year and a half. To combat global warming, scientists at Harvard University will attempt to reproduce that effect by spraying sulfate particles into the stratosphere.

As early as first few months of 2019, Stratospheric Controlled Perturbation Experiment (SCoPEx) could launch a propelled balloon up to a distance of 20 kilometres above Earth’s surface, releasing about 100 grams of calcium carbonate at a time. This should create a perturbed air mass 1 km long and 100 metres wide which equipment attached to the balloon will measure changes in atmospheric chemistry and light scattering. Calcium carbonate was chosen because it should less impact on ozone than other options. Water will be sprayed first to test the mechanism. If all goes well, the scientists could try sulfates or other materials that would absorb more sunlight.

The best-case scenario would be that someday high-flying planes spray particles into the stratosphere, reflecting inbound sun rays and reducing global temperatures by 1.5 degrees celsius for a cost of less than $14 billion per year. Considering the cost of natural disasters caused by global warming, this would be a bargain. There is a long way to go before that has any hope of becoming a reality, however. The vast majority of scientists, including the SCoPEx team, agree that lowering emissions is a much more realistic option. Still, the idea of solar geoengineering goes to show the power of human ingenuity.