Stopping the rise in average global
temperatures is expected to be one of the great challenges of the
21st century. Transitioning away from a fossil fuel
dependent economy, one that has been dominant for over 100 years,
will be no easy feat. That's why some researchers have begun to look
at alternative methods to cool the planet, called geoengineering. One
such method, called stratospheric aerosol injection, involves
releasing aerosol particles into the stratosphere, the layer just
above where the majority of Earth's weather occurs, in order to
reflect just enough of the incoming sunlight to curb the rise in
global temperatures. At first glance, this might seem like an easy
fix, as volcanoes essentially do the same thing when they release
fine ash into the stratosphere and temporarily cool the planet.
However, according to a 2020 computer modeling study from scientists
around the world, including MIT and Indiana University, such an easy
fix would create negative climate consequences of its own.
The research team employed computer climate models to examine a number of different future scenarios of geoengineering. One of them, called G1, would see just the right amount of aerosols released to offset a quadrupling of carbon dioxide emissions. Under this scenario, the strength of extratropical storms (the low pressure systems which frequently bring rain and snow to the mid-latitudes) would weaken in both the Northern and Southern Hemispheres. While this would mean less powerful, damaging storms like nor'easters, it would also significantly reduce the amount of precipitation at middle latitudes. Weaker extratropical storms would also lead to more stagnant weather patterns, potentially leading to more persistent heatwaves and less ventilation and mixing of air pollution.
The main reason why extratropical storms are expected to weaken under this geoengineering scenario is the cooling of temperatures near the equator, because of reduced incoming solar radiation, while areas near the poles continue to warm. The net effect would be to lessen the temperature difference between the equator and the poles. This temperature difference is one of the key drivers of extratropical storms.