The strongest of the infamous New England gales known as nor’easters have gotten even stronger since the 1940s, threatening to do more damage to the US north-east coast. This is probably due to warmer ocean temperatures.

“We know what’s causing the warming of sea surface temperature: the emission of greenhouse gases. And it’s that increase that’s driving the trend,” says at the University of Pennsylvania.

Mann and his colleagues assembled a dataset of nor’easters and their meandering paths over the past 85 years. They used a statistical method to identify any trends in the maximum wind speed of the storms, as well as any changes in precipitation.

“What we found is that, while we couldn’t isolate any significant trend in the average intensity of these storms, we found the strongest of these storms are getting stronger,” says Mann.

This dynamic occurs because of how the ocean temperatures that fuel the storms interact with other factors, such as wind shear, to decide their ultimate intensity, he says. Weaker storms are more likely to be influenced by factors other than ocean temperature, which determine the maximum potential intensity of a storm. “The biggest storms, to be a bit anthropomorphic here, have the opportunity to reach their potential,” says Mann.

While hurricanes at tropical latitudes were known to behave this way, it was less clear how more complex nor’easters would respond to warmer temperatures. “Nor’easters, in contrast to hurricanes, derive their energy from a lot of other factors,” says at the University at Albany in New York state.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

The upward trend in both intensity and precipitation is small – the change in wind speed of even the strongest storms amounts to just under 2 metres per second since 1940. But this can still affect how much damage the nor’easters do.

Storm surge, combined with sea level rise, drives flooding along the coast, and more snow and rain boost inland flooding. “I think the big danger is water,” says Tang.

A children’s hospital that lost access to water in the wake of Hurricane Milton is now using a device that can collect drinking water directly from the air, in a test of how such atmospheric water harvesting systems could be used to respond to disasters.

“When a hospital has both water and power you’re good,” says at Genesis Systems, the Florida-based company that designed the apparatus. The system uses absorbent materials called metal organic frameworks to concentrate moisture from air pumped through the machine, then releases pure water when the material is heated by around 8°C.

Such atmospheric water harvesting systems have long attracted interest because of their ability to operate independently of other water infrastructure. A small but growing number are installed to supply daily water to off-grid communities, and they have been used in cities with poor water infrastructure or arid places where water supplies are unreliable, as well as for military operations. An Arizona-based company called Source that makes solar-powered “hydropanels” has even started selling its air water in cans.

Another way these flexible systems have been used is to respond to disasters that leave communities without a reliable clean water supply. As Hurricane Milton approached Florida’s west coast, , the secretary of the Florida Agency for Health Care Administration, saw an opportunity to try this out.

With Hurricane Ian in 2022, Weida saw how water issues and power outages required some hospitals to close for weeks, with evacuation sometimes required days after the storm itself had passed. He learned about Genesis Systems’ technology while touring damage from Hurricane Helene, which made landfall on 26 September. “I thought, “Wouldn’t this be great for next year’s hurricane season?” he says. “Little did I know that two weeks later we would be preparing for Hurricane Milton.”

Ahead of Milton’s landfall on 9 October, the system was brought to a staging ground for the state’s disaster response. Soon after the hurricane passed, a truck brought it to Johns Hopkins All Children’s Hospital in St. Petersburg where leaking water mains had interrupted the hospital’s water supply. Weida says this particular hospital was a priority because of how challenging it would be to evacuate newborns from the hospital’s large neonatal intensive care unit.

On 10 October, workers hooked up the shipping-container sized system to a generator, and it is now producing up to 2000 gallons of drinking water per day while the hospital’s regular water supply is being fully restored. Stuckenberg says the system can operate more or less anywhere humidity is above 10 per cent, although it becomes less efficient as humidity declines. He estimates that the system installed in Florida’s humid air uses about 0.8 kilowatt hours of electricity per gallon of water.

at Virginia Tech questions whether the system really can harvest so much water while using so little energy. He says it may still be useful in an emergency scenario, but without more information about how it works, he is sceptical about its claimed efficiency.

Stuckenberg points to a study that he and his colleagues published in 2022, which . He says the system’s energy requirements are so low because of the way the material they use bonds to water vapour with almost no energy, with most energy used to run fans, pumps and to re-concentrate the absorbent. The 2022 study suggested the system has a theoretical maximum efficiency of just 0.07 kilowatt hours per gallon of water.

In a more general sense, atmospheric water harvesting systems can be an “important tool” for disaster response when water supplies might be offline for an extended period of time, says at Arizona State University, and are well-suited for places with relatively high humidity like Florida. However, he says their reliance on electricity, often from a generator, has been an issue during past disasters.

Hurricane Milton has spawned at least two large tornadoes ahead of making landfall on Florida’s west coast later tonight, and a tornado watch has been issued for much of the southern part of the state.

Such tornadoes are not uncommon – they are observed in more than that made landfall in the Gulf Coast – but it is unusual for them to be so clearly visible ahead of the hurricane, says at Iowa State University. “There have been a surprisingly large number already and they look like Great Plains tornadoes,” he says. “They’re wide.”

There are two main ingredients needed for hurricanes to spawn tornadoes, which add to the destructive potential of a storm. The first is instability created by heat and humidity in the atmosphere. The second is differences in wind speed and direction at different altitudes, known as wind shear.

Hurricanes moving over water normally have relatively low wind shear because there isn’t much friction between the storm and the sea surface. “It is like this giant spinning cylinder, so the winds aren’t very different on the ground than they are up high,” says Gallus.

That changes as the storm makes landfall, and friction with the ground slows winds at lower altitudes, which also drives them towards the centre of the storm. When the air is hot and humid enough, these intense winds can form tornadoes.

In this case, bands of wind ahead of the main body of Milton have reached the coast, creating wind shear and spawning tornadoes, says Gallus.

Along with other hurricane hazards like storm surge and heavy precipitation, such tornadoes can cause substantial destruction, their path sometimes visible in the pattern of debris they leave behind. By one , about 3 per cent of tropical-storm related deaths in the US were caused by the tornadoes they spawned; an earlier  put the number at 10 per cent of fatalities.

Such tornadoes may also become more frequent as climate change raises temperatures in the lower atmosphere, adding to the unstable conditions under which tornadoes form. In a recent , Gallus and his colleagues simulated how four different hurricanes – Ivan, Katrina, Rita and Harvey – may have behaved with warming expected by mid-century under a very high emissions scenario. They found the number of tornadoes spawned by each storm in their simulation rose substantially, ranging from a 56 per cent increase for Harvey to a 299 per cent increase for Katrina.

“Even if you only end up with half as much it would be a very noticeable increase in the number of tornadoes,” says Gallus.

Why is high-purity quartz so important?

Free newsletter

Sign up to The Weekly

Sign up to newsletter

Where does high-purity quartz come from?

How did Hurricane Helene impact quartz mining operations?

Will Helene disrupt the supply of semiconductors?

The superconductor breakthrough that could mean an energy revolution

We’ve finally made a room-temperature superconductor, so materials that transport electricity without wasting any of it are within our grasp

Are there alternative sources of quartz for the global semiconductor industry?