When the subject of the world's most lucrative future industries arises, the business and financial worlds usually speak of coming bonanzas in AI, robots, the internet of things, 5G and driverless cars. What goes all but unmentioned is a nearer-term play that rivals them in scale — the utterly embryonic business of extreme weather.

What's happening: Over the next 5 years, existing global companies estimate that they will earn more than $2.1 trillion in revenue from services such as financing, building and hardening resilient infrastructure, according to a groundbreaking survey.

If accurate, the sum, based on estimates from a survey of 7,000 companies representing half the market cap on the world's major stock exchanges, is remarkable given that the industry has only just begun.

based on estimates from a survey of 7,000 companies representing half the market cap on the world's major stock exchanges, is remarkable given that the industry has only just begun. "So many companies are used to thinking of only the risk side of climate change. But here is $2 trillion of opportunity in the next 5 years from leaning into the transition," says Bruno Sarda, a senior executive with CDP, the U.K.-based environmental disclosure nonprofit that produced the survey.

The big picture: Historically speaking, some of the greatest global fortunes have been earned in episodes of chaos, like war, economic depression and natural disaster, when profiteers have figured out how to manipulate circumstances to personal advantage.

And for years it has been plain that climate-influenced extreme weather — outsized hurricanes, unusual heat and cold, tornadoes, drought, floods and wildfires, not to mention rising seas — is exactly this type of event.

that climate-influenced extreme weather — outsized hurricanes, unusual heat and cold, tornadoes, drought, floods and wildfires, not to mention rising seas — is exactly this type of event. What has not been known is what types of businesses will arise to profit over the coming years, decades and even centuries.

is what types of businesses will arise to profit over the coming years, decades and even centuries. And businesses have been loath to talk about it, partly out of fear of appearing to be planning to profit from mass misery.

Driving the news: Now, though, companies are talking. The turning point was 2017, the year of hurricanes Irma, Jose and Maria, not to mention enormous deadly wildfires in California. "Those really brought it home for U.S. businesses," says Emilie Mazzacurati, founder of Four Twenty Seven, a Berkeley, California-based firm that calculates the risk posed to physical assets by extreme weather.

In a small sign of this future windfall , Moody's said Wednesday that it bought a controlling share of Four Twenty Seven, whose clients are businesses like power and real estate companies assessing their financial exposure to extreme weather events. The terms of the deal were not disclosed.

, Moody's said Wednesday that it bought a controlling share of Four Twenty Seven, whose clients are businesses like power and real estate companies assessing their financial exposure to extreme weather events. The terms of the deal were not disclosed. What Four Twenty Seven does: The company overlays climate models and geographical maps of a company's assets and then forecasts the climate risk to the holdings as far out as 2040, Mazzacurati tells Axios.

At that stage, the companies can figure out how they want to respond — or not — by reinforcing, replacing or retiring exposed assets, all of which would be part of the future extreme weather industry.

What's next: CDP's Sarda says that the 5-year revenue estimate is actually likely to be larger than $2.1 trillion because that's only the sum from 224 companies that answered the survey in great detail. On top of those are roughly 6,775 companies that gave incomplete answers, in addition to the thousands or perhaps tens of thousands of startups yet to be created in response to the weather.

Where the revenue may be earned: