Saturday, October 24, 2015

Did Climate Change Cause Super Hurricane Patricia?

Intense super Hurricane Patricia off the Mexican
west coast Friday morning.  
Hurricane Patricia, the most intense hurricane in modern records seen in the western hemisphere, slammed into Mexico as expccted Friday afternoon and evening.

The wildest winds with Patricia hit in a relatively sparsely populated spot on the Mexican west coast.

The worst of the winds appeared to miss the busy resort city of Puerto Vallarta and the port of Manzanillo so it could have been worse.

Both of those two bigger cities got nasty, damaging winds, but not the full blow of Category 5 winds of over 150 mph.

We are still awaiting full damage reports. So far it doesn't seem too, too bad, but we haven't heard from remote areas yet. So there will surely be more news on this.

There's no doubt Patricia was a meteorological shocker. Nobody expected it to get that strong.

It's leading to the inevitable question: Did climate change, global warming, however you want to describe it, cause Hurricane Patricia? Or at least make it worse?  Should we have renamed Patricia Hurricane Exxon, after the fossil fuel giant, as some social media wags suggested, because of global warming?

More on that in a moment. First, some perspective.

As I said, Patricia was the strongest hurricane on record in the western hemisphere. I'm resisting the urge some people have had to call it the strongest hurricane ever.

Scientists are much better at measuring hurricanes over water via satellite estimations and hurricane hunter flights than they were many decades ago. Perhaps a stronger western hemispheric hurricane occured over water, say, a century ago and we missed it.

Nor was Patricia "big." It was a compact hurricane, with the 200 mph winds limited to a 10 mile wide area, and hurricane force winds sometimes confined to within as little as 35 miles across

Even with these caveats, Patricia was in a rare class of intense hurricanes. It weakened a bit to sustained winds of165 mph at landfall, but that's still extremely intense ande extremely dangerous.

Imagine one of those immense, super strong Midwestern tornadoes sitting over your house for more than an hour, instead of the exceptionally frightening couple of minutes a tornado would.

So why was Patricia such a monster?

The two main things you need for an intense hurricane are light upper level winds and warm ocean water. The calmer the upper atmospheric winds and the warmer the water, the stronger the hurricane, at least usually.

Patricia took advantage of calm upper level winds. That was just a matter of being in the right place at the right time. The hurricane formed under these conditions.

The water beneath the storm was at record high levels. Aha! Global warming caused Patricia, right?

Well, it certainly could have been a contributor, but that's not the whole story. Yes, the water was record warm. That was largely due to El Nino, the periodic warming of eastern Pacific waters.

This El Nino is stronger than almost all of them in the past 100 years or so, so this El Nino has more warm water than usual. That the water was at record temperatures could well have been given that boost due to global warming.

So yes, climate change might have influenced Hurricane Patricia, but the story is even more muddier than I let on.

First of all, it's hard to pin one extreme event like Patricia on global warming, when there are so many complicated factors that went into Patricia's formation.

We do know that global warming is causing, and will cause, more extreme heat events, extreme droughts and extreme rainfall events. That's pretty well established by scientists, who I trust a lot more than Donald Trump, who disagrees with this assessment.

Patricia was one more extreme event amid many others that have happened recently. Like the big flash floods in Texas Friday that will probably become more intense when moisture from Patricia's remnants enter the picture today.

The basic question remains: Will there be more serious and stronger hurricanes and typhoons because of global warming?

Individual cases suggest yes. Super Typhoon Haiyan in 2013 and Superstorm Sandy in 2012 along the U.S. East Coast seem to have given a boost by unsually warm water temperatures, a hallmark of climate change.

But does climate change also disrupt upper level winds? Does it increase those winds, making it harder for hurricanes and typhoons to form? If so where? It seems the science isn't totally settled there.

Maybe global warming will change where hurricanes and typhoons hit. If warmer water is more north than it used to be, it stands to reason that hurricanes would travel more north than they used to. That, again, depends on whether upper level winds also cooperate to help form these monster storms.

Some research also suggests that perhaps the overall number of hurricanes might not increase, but the number of really strong ones, like Haiyan and Patricia would rise due to tropical systems using all that newly hot ocean water as a fuel source. 

A bunch of scientists are studying hurricanes and typhoons and how they relate to global warming.

The bottom line: The science on specific super Hurricane Patricia is a little murky, but climate change is probably - but not definitely- making vulnerable coastal locations in both the Atlantic and Pacific Oceams more prone to stronger hurricanes like Patricia.

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