Researchers at the University of Washington say that suggested method would likely achieve only part of the desired effect and could carry serious, if unintended, consequences.
Tiny sulfate and sea salt particles, called aerosols, are naturally present in the lower atmosphere and reflect energy from the sun into space.
Some researchers have suggested injecting sulfate particles directly into the stratosphere to enhance the effect.
However, a UW modeling study shows sulfate particles in the stratosphere will not necessarily offset all the effects of future increases in atmospheric carbon dioxide.
Significant changes would still occur because even increased aerosol levels cannot balance changes in atmospheric and oceanic circulation brought on by higher levels of atmospheric CO2, researchers said.
"There is no way to keep the climate the way it is now," Kelly McCusker, a UW doctoral student in atmospheric sciences, said.
"Later this century, you would not be able to recreate present-day Earth just by adding sulfate aerosols to the atmosphere."
And the odds of a "climate surprise" would be high because the uncertainties about the effects of geoengineering would be added to existing uncertainties about climate change, the researchers said.