Hacking the climate using two geoengineering tools together – injecting sulphate particles into the atmosphere and thinning out cirrus clouds – could bring down global average temperatures and rainfall back to pre-industrial levels, a new study suggests1. These averages, however, won’t work at a local level due to the spatial variability of the climate system.
“This is the first geoengineering climate modelling study to show that both the global mean temperature and precipitation can be simultaneously restored to pre-industrial levels,” says Govindasamy Bala, one of the co-authors and a professor at the Centre for Atmospheric and Oceanic Studies, Indian Institute of Science, Bengaluru. The other collaborators are from Zhejiang University, Hangzhou, China, and Department of Global Ecology, Carnegie Institution, Stanford, California, USA.
Geoengineering tools seek to reduce incoming sunlight to fix global warming. In the stratospheric aerosol geoengineering method, sulphate particles are pumped into the stratosphere where they form a layer that obstructs sunlight from getting into the troposphere below, where weather happens. In the cirrus cloud thinning method, thin and wispy cirrus clouds that trap greenhouse gases at high altitudes, are seeded with ice nucleating particles to thin them out.
By combining these two radically different radiation management techniques, the researchers simulated a “cocktail” effect to restore both global mean temperatures and precipitation.
Geoenginering gets a bad rap because of unintended consequences and also because it sidesteps the goal of reducing carbon emissions. Bala says though the foremost focus should be on CO2 emission reductions, it is also important to continue geoengineering research as all options should be on the table for solving the climate crisis.
