The team of researchers began with an ideal scenario in which the solar sunlight reflected was enough to set off the global warming caused if the concentration of carbon dioxide were to quadruple.
World Environment Day 2020: MIT study highlights ill-effects of reflecting sunlight! Global warming is real and it is happening. But how can we tackle this? Some scientists were exploring methods to protect the Earth from a part of the Sun, by sending reflective aerosols into the stratosphere so that they could block the Sun’s heat and reduce global warming. This is known as solar geoengineering. However, a study by scientists at the Massachusetts Institute of Technology (MIT) has now brought to light the reasons why that may not be the best idea, and the ill-effects of such a step.
A team of scientists from MIT have published a paper in the journal Geophysical Research Letters that such schemes would cause a significant change in the extratropical storm tracks, which are the zones in the high and middle latitudes where storms are formed throughout the year, and are then taken across oceans and lands with the help of jet streams. These tracks give rise to extratropical cyclones and not tropical hurricanes. As per a statement by MIT, the strength of these tracks determines the frequency as well as the severity of the storms.
Solar geoengineering: The study
The team of researchers began with an ideal scenario in which the solar sunlight reflected was enough to set off the global warming caused if the concentration of carbon dioxide were to quadruple. Several climate models under this scenario showed that the storm tracks would weaken in both the southern and northern hemispheres. In the northern hemisphere, storm tracks could weaken by as much as 5-7%.
While weakened tracks would lead to less powerful winter storms, it would also result in stagnant conditions in summers especially, and lack of wind to clear away air pollution. Moreover, if wind conditions were to change, the circulation of ocean waters would also change and the stability of ice sheets would also be affected.
The MIT statement quoted graduate student in the Department of Earth, Atmospheric and Planetary Sciences (EAPS), Charles Gertler as saying that around half the people in the world live in regions where extratropical storm tracks dominate the weather. He further said that their study found that solar geoengineering would not reverse climate change as simply as researchers seem to feel, it, in fact, has the ability to introduce novel changes to the climate itself.
He said that the weakening of storm tracks could affect heat waves, the ventilation of air pollution in all the seasons, and the hydrological cycle, with “regional reductions in rainfall”.
Global warming: Puzzling discovery
The team also decided to study the impact of global warming, without solar geoengineering, on the strength of the extratropical storm tracks. But what they found has left them puzzled.
In the northern hemisphere, global warming would also weaken the storm tracks by the same magnitude as with solar geoengineering, indicating that as far as storm tracks are concerned, the efforts to reduce incoming heat would barely impact the effects of global warming.
However, in the southern hemisphere, scientists found that global warming acting alone would strengthen the storm tracks. Meanwhile, if solar geoengineering is added to the mix, not only would it negate this strengthening, it would also weaken these tracks.
EAPS professor Paul O’Gorman was quoted as saying that in the southern hemisphere, ocean circulation is driven by winds, in turn affecting the uptake of carbon dioxide and ice sheet stability. This makes the changes in storm tracks in the southern hemisphere very important, he said.
Moreover, the team found that storm tracks weakening impacted the temperature and humidity. Models showed that if the incoming solar radiation is reduced, the equator would coll significantly, while the poles would continue to warm. Gertler said that the study proves that solar geoengineering would not reverse climate change, but in fact would substitute the current form of climate change for another unprecedented state.