One potential downside to the robot revolution: Automation could increase income inequality.

So says a new report about the growing use of robots worldwide.

“This great displacement will not be evenly distributed around the world, or within countries,” according to the report from Oxford Economics. “Our research shows that the negative effects of robotization are disproportionately felt in the lower-income regions compared with higher-income regions of the same country.”

Report: Robots will replace 20M manufacturing jobs by 2030; NC will take big hit

The workers who drive knowledge and innovation within the manufacturing industry tend to be concentrated in larger cities, and those skills are harder to automate. That’s why urban areas will deal better with the increased automation, according to the report.

On the whole, the increased use of automation will likely create new jobs at a pace comparable to the jobs that will be lost, which nullifies fears about permanent job destruction, according to the Oxford study. That said, the poorer regions that are expected to lose the most jobs will probably not benefit equally from this new job creation due to a gap in skills. That will lead to increased income inequality between cities and rural areas, as well as between regions.

“Automation will continue to drive regional polarization in many of the world’s advanced economies, unevenly distributing the benefits and costs across the population,” the report said.

For policy makers, this means they will have to think about how the increased efficiency will hold up against the effect on income inequality. Some have already worked automation into their political platforms. Vermont Senator Bernie Sanders, who is running for the Democratic nomination for president, recently said he was worried about what artificial intelligence and robotics “will mean to working people in this country,” for example.

“We need to have a long discussion to make certain that millions of workers are not thrown out on the street because of robotics,” he said during a CNN town hall in February.

Robot vulnerability index: Factoring why NC is likely to suffer big job losses