It’s the strongest hurricane to ever form in the Western Hemisphere, according to the National Hurricane Center (NHC). With gusts of up to 247 mph and a record-breaking 880 millibars of central pressure, Hurricane Patricia was a big, mean surprise for Mexico’s western seaboard.
Though the Category 5 hurricane weakened to a Category 2 storm by the time it made landfall on early Saturday, the NHC warns that heavy rainfall is likely to cause life-threatening flash floods and mudslides in the Mexican states of Nayarit, Jalisco, Colima, Michoacan and Guerrero throughout the day.
Hurricane Patricia rapidly formed into the strongest storm this side of the planet has ever measured, but does that mean climate change is to blame?
— Scott Kelly (@StationCDRKelly) October 23, 2015
What Caused Hurricane Patricia to Get So Big So Fast?
CNBC reports that Patricia’s “rapid intensification” was a shock to researchers. As Kerry Emanuel, an atmospheric scientist at MIT, explained, “Usually, when hurricanes try to intensify up that speed limit, they begin to churn up cold water, and that starts to slow them down. That is particularly true in the Eastern Pacific.” This time, however, two notable factors prevented Patricia from hitting that cold speed limit. First of all, the ocean is a lot warmer than it used to be. The National Oceanic and Atmospheric Administration (NOAA) has recorded a steady rise in the ocean’s heat content (from depths of zero to 2,000 meters) since the late 1960s. This is due to the fact that the ocean absorbs about 90 percent of the planet’s heat and, for a long time now, the planet’s thermal energy has been increasing. This process has notably increased in the last several years, to the point that Dr. John Abraham, professor of thermal sciences at the University of St. Thomas, has said that oceans are warming so quickly they are “breaking scientists’ charts.”
As Dr. Emanuel told CNBC, not only is the top layer of ocean water warmer than usual, that layer is also bigger and less salty than usual. Less salt makes the water lighter than the colder, heavier water below, meaning it does not mix as well, meaning the cold water that would normally stop a hurricane from getting as intense as Patricia just isn’t there. The other factor at work is this year’s El Niño, which has been gathering strength since March. El Niños typically cause an increase in hurricane activity in the Eastern Pacific basin.
Is This a Result of Climate Change?
Unfortunately, we can’t give you a black and white answer here. There are several meteorological factors that prevent scientists from saying whether or not one specific hurricane is due to climate change. What we can say with absolute certainty, however, is that many scientific models predict more intense hurricane activity under global warming conditions.
One recent study published in the journal Nature Climate Change calculated that the frequency of global tropical cyclones may decrease under global warming conditions, but that their intensity will increase. Dr. Emanuel echoed this finding when he spoke to CNBC.
“We have set a record number of category 4 and 5 hurricanes in the Northern Hemisphere, and it is the consistent consensus that warming is contributing to the intensity of storms,” he said. “We expect the frequency of high-intensity events to increase.”
But if we’re going to be scientific about all this, we can’t say definitively that hurricanes like Patricia and Haiyan are a direct result of climate change. There just isn’t enough data yet.
That being said, James Elsner of Florida State University recently made this salient point: Rather than asking whether climate change caused Hurricane Patricia, “[a] better question to ask is, what kind of storm would it have been without climate change?”
What has meteorologists really worried is just how quickly Patricia formed. That makes it more difficult to issue accurate warnings in time.
“When you have a storm over very warm ocean water and optimal conditions, these systems can really ramp up in a hurry, like Patricia,” Dr. Phil Klotzbach, of the Tropical Meteorology Project at Colorado State University, told New Scientist. “A garden variety tropical storm one day, and then the next day, a massive Category 5.”
On Saturday, the storm’s core passed within about 55 miles of Manzanillo, with a population of about 110,000 people. Footage is embedded below.
— Geól. Sergio Almazán (@chematierra) October 24, 2015