Building three "Great Walls" across Tornado Alley in the US could eliminate the disasters, a physicist says.
The barriers - 300m (980ft) high and up to 100 miles long - would act like hill ranges, softening winds before twisters can form.
They would cost $16bn (£9.6bn) to build but save billions of dollars of damage each year, said Prof Rongjia Tao, of Temple University, Philadelphia.
He unveiled his idea at the American Physical Society meeting in Denver.
However critics say the idea is unworkable, and would create more problems than it solves.
Every year hundreds of twisters tear through communities in the great north-south corridor between the Rocky and Appalachian Mountain ranges.
The proposed walls would not shelter towns - they would not be strong enough to block a tornado in motion.
Instead, they would soften the clashing streams of hot southern and cold northern air, which form twisters in the first place, Prof Tao said.
"If we build three east-west great walls, one in North Dakota, one along the border between Kansas and Oklahoma, and the third in the south in Texas and Louisiana, we will diminish the threats in Tornado Alley forever," he said.
"We've already been doing computer simulations and next we aim to build physical models for testing [in wind tunnels]."