Mexico is bracing for Patricia. This morning, the Category 5 hurricane officially clocked in as the most powerful tropical cyclone ever measured in the Western Hemisphere – and close to the theoretical maximum strength for any tropical cyclone on our planet.

As with other extraordinary weather events of late, there’s a question lurking in the back of many people’s minds: is climate change to blame? In a warmer world, scientists say they expect to see storms more intense, and thus more destructive, than before.

In Hurricane Patricia’s case, a confluence of events – already warm oceans, piled on with other factors that kept them that way – allowed the storm to form.


2015 is an unusually strong year for an El Niño, the periodic phenomenon of warm sea surface temperatures in the Pacific. In an El Niño year, hurricane activity tends to get a boost in the central and eastern Pacific basins.

One study, published in May, discovered a strong connection between rising ocean temperatures and the intensity of tropical storms. A newly forming hurricane draws its energy from warm water evaporating off the ocean surface. The hotter the ocean is, the stronger a storm’s winds can get.

“We do have conditions now where disasters can be without precedent,” says James Elsner of Florida State University, who led the research. “The point is really about if we’re going to continue to break intensity records with storms, and I think Patricia has done that in the Pacific.”

Compounding the issue is a pocket of warm overseas temperatures that keeps the water’s temperature high, says Phil Klotzbach of the Tropical Meteorology Project at Colorado State University. Add in a lull in cyclones that could have siphoned away some of the heat, plus little change in the hurricane’s wind speed, and you’ve got the recipe for one mighty storm.

It’s an unusual mixture of ingredients, but one that scientists can imagine meeting again in the future.

“When you have a storm over very warm ocean water and optimal conditions, these systems can really ramp up in a hurry, like Patricia,” says Klotzbach. “A garden variety tropical storm one day, and then the next day, a massive Category 5.”

Putting an exact figure on how much climate change influenced Patricia is a bit trickier. Doing so requires sophisticated models that can accurately simulate not only the real world, but what the world would look like without greenhouse gas emissions.

At a workshop convened in Washington DC, this week, Tom Knutson at the National Oceanographic and Atmospheric Administration outlined several obstacles to attributing hurricanes to anthropogenic climate change. Data is one major stumbling block: scientists need a lengthy and reliable log of past hurricanes to confidently assess climate change’s impact.

But asking whether climate change caused Patricia specifically is the wrong question, says Elsner. “A better question to ask is, what kind of storm would it have been without climate change?” Perhaps a less extraordinary one.

(Image: NOAA)