Bill Gates is sounding the alarm about artificial intelligence, warning in a new essay that the technology will rapidly transform the U.S. labor market and put millions of jobs at risk.

AI is changing the economy much faster than previous technological revolutions, advancing at what the Microsoft co-founder called a "mind-blowing rate" and leaving less time to prepare for employment disruptions.

"AI will take on work in law, customer service, medicine, software, and manufacturing. It will hit these industries rapidly, over the course of a decade rather than a few generations," Gates wrote in an article posted on his personal website published on Wednesday. "There will be some new jobs, but without the right policies, there will be far fewer than exist today."

While Gates outlines what he describes as a number of risks posed by AI in his nearly 6,000-word essay, he focuses in large part on how the technology could affect American workers. As AI's reasoning skills improve, it's becoming a more direct competitor to human cognitive abilities, according to Gates.

"The biggest shift for workers will happen when AI provides nearly error-free work," he wrote. "At that point, it will be able to function on its own without a human checking in on it, and companies will have every economic incentive to let it."

AI is already changing white-collar professions as companies offload tasks such as data analysis to AI, reducing the need for human labor, Gates noted. He also expressed concern for young people entering the workforce amid fewer job openings.

But desk jobs aren't the only ones at risk, Gates warned. AI will soon be able to do physical work just as well as humans, he argued, which could weigh on blue-collar jobs like construction.

"I think 'smart' robots will begin to compete with people on some physical tasks — in the construction and hospitality industries, for example — by the end of the decade," he wrote.

Humans only?

To prepare for such changes, Gates said it is urgent to discuss policies to mitigate AI's impact on jobs. One idea would be to introduce a tax on AI tokens and robots, a move Gates argued would slow companies' displacement of human workers.

"Right now, if you're an employer and you hire someone, you pay payroll taxes on their earnings," he wrote. "But if you buy a robot, you can usually write it off right away as a business expense. The tax system nudges you toward replacing people with machines."

Gates also advocates reserving certain jobs, such as caregiving, for people, noting that humans are better able to handle certain responsibilities than robots. He equated that approach to creating a nature preserve in which societies choose to protect land rather than build on it.

"Some countries might insist on having humans take care of the elderly," he wrote. "But a country like Japan, which has a shrinking workforce and not enough young people to care for the old, may welcome a caregiving robot."

The rapid advances in AI mean policymakers, legislators and other decision makers must act now to develop a framework to address potential disruption from the technology.

"I believe we need time to prepare for the period of social, political and economic upheaval we are about to enter," Gates said. "The people who need the most time are the ones who have the least — the accounting worker who's replaced by a bot or the $20-an-hour worker who loses their job to a $10-an-hour robot."