There is nothing super about mega, extra-tropical hybrid storm Sandy that scoured the New Jersey coast line, flooded New York City’s vast subway system and dumped feet of snow in West Virginia. But it is a shocking and awe-inspiring natural disaster. Thanks to this late season hurricane that merged with an Arctic low pressure system extreme weather records have been falling left and right. And this is an area of approximately 67 million people, many of whom felt mother nature’s force last year when Hurricane Irene barreled up the east coast.
New York power company officials say the electrical system is overtaxed because they are dealing with the aftermath of a hundred-year-storms every other year. And in this case, twice in two years.
One of the clear signals of climate change is the increase in frequency of extreme events. And Superstorm Sandy certainly qualifies as an extreme event. For one, it is a storm that had the lowest low pressure ever recorded in our hemisphere. It’s the first weather disturbance to shutter Wall Street, knock out power to huge swaths of New York City and the resulting storm surge marks the first time the New York subway system was inundated by seawater.People are still trying to locate loved ones, regain electricity and flush out standing water on city streets. They are trying to get back to normal after a devastating weather event and one that few could have seen coming. Though the climate connection was conspicuously absent in the run-up to the storm itself, climate is making headlines in the aftermath.
NBC News anchor Brian Williams says, “A storm like this has a way of making you ask questions like, ‘What’s happening to our world and our weather?’”
But scientists have been watching the gradual changes in climate for many years, knowing that these types of massive storms would start to become more frequent. While it is still very difficult to blame one particular weather event on global warming Super Storm Sandy demonstrates what happens when some indicators of climate change line up together.
Dr. Kevin E. Trenberth is Head of the Climate Analysis Section at the U.S. National Center for Atmospheric Research in Boulder, Colorado. He says, “We have a new normal, really. The background environment for all weather systems has changed.”
And while the background environment Trenberth refers to–like ocean temperature, acidification, sea level rise and changes in atmospheric chemistry–is hard to see. All of those elements contributed to the destructive nature evident in Super Storm Sandy.
Director of Penn State’s Earth System Science Center Michael Mann says, “All of these factors interact with any storm including the one that we just say with Sandy.”
If the Gulf Stream–the warm sub-sea surface jet of warm water that stretches from the Caribbean to the north Atlantic Ocean and keeps Europe temperate–was not 5-9 degrees F above normal, Hurricane Sandy would likely have lost momentum as it traveled north into cooler waters. As it was, the ocean temperatures along the whole eastern seaboard were well above normal this year, creating the necessary fuel for a hurricane to strengthen north of North Carolina.
Trenberth says that warming caused by carbon dioxide in the atmosphere shows up in the ocean and increases temperatures and sea levels as a result. He says, “The oceans are warmer than they used to be. Not just at the surface but below the surface.”
In September National Oceanic and Atmospheric Administration (NOAA) reported some warm records. It was the fourth warmest August ever, the third warmest summer, and the warmest first 8 months of the year ever. And in the spring NOAA scientists discovered an unusual warming event off the northeast coast of the U.S.
NOAA’s Northeast Fisheries Science Center scientist Kevin Friedland focuses on fish stocks in the region and was referring to effects on marine life when he said, “A pronounced warming event occurred on the Northeast Shelf this spring, and this will have a profound impact throughout the ecosystem.”That warming event caused temperatures in Delaware and Chesapeake Bay to be 11 degrees F above the 20th Century average at the surface and a full 9 degrees F above the average at the bottom. Similar increases in ocean temperatures were recorded up and down the eastern seaboard, including nearly four degrees above normal in the Gulf of Maine.
Generally, if a hurricane does make a bee-line for the Northeast U.S. it gets pushed out to sea by a powerful air current called the Jet Stream. But the Jet Stream has shifted and is very far north and jutting far south creating a steep V in the middle of the country. Generally it flows west to east in a fairly straight line, except when interrupted by high or low pressure systems that push it north or south. With Jet Stream was far north a giant Arctic low pressure system was able stream out of Canada. Instead of pushing the hurricane offshore that polar low sucked the storm to the coastline at the same time that it gave it more energy.
Massachusetts Rep. Ed Markey (D) says, “The Arctic is melting and as a result that is changing the Jet Stream which ordinarily would have put this storm off to sea.” He is the chair of the House special committee on Energy Independence and Global Warming. Just a day after the storm made landfall he said, “For this superstorm to occur so late in the storm season, reach such fury, and have the kinds of flooding impacts that we are seeing, is fully consistent with what scientists have told us we should expect due to global warming.”
In April, a study by Jennifer Francis of Rutgers University and Stephen Vavrus of the University of Wisconsin-Madison found that rapid Arctic warming is altering the path of the jet stream. The study found the jet stream becoming “wavier” with steeper troughs and higher ridges. They also found that storm systems are progressing more slowly which allows extreme weather events to stick around longer.
Francis says, “The tendency for weather to hang around longer is going to favor extreme weather conditions that are related to persistent weather patterns.” She and Vavrus also found that Arctic climate change may increase the odds that such high-impact, blocking weather patterns will occur.
The slow-moving Superstorm Sandy is a blocking event. So was the March heatwave across the Midwest and the hot summer in Texas that caused a devastating and costly drought. Sandy is a low pressure system that is in no hurry to get out of the way while the late winter heatwave and summer drought were caused by snail-paced high pressure systems.
Scientists believe that the difference in temperatures between the Arctic and the mid latitudes is decreasing. This is causing the westerly component of upper-level winds to slow, especially during the fall when extra heating in the Arctic is exceptionally strong. Those crucial winds that determine much of our day-to-day weather have decreased 14 percent since 1979.
The reduced temperature gradient between the Arctic and mid latitudes may also be responsible for the more pronounced north/south swings of the jet stream.
Superstorm Sandy is a very unusual storm because it is a hybrid storm. It started out as a hurricane but once the core of the storm shifted from warm to cool–as it traveled north and encountered waters well below 80 degrees F–it became an extra-tropical cyclone. On the east coast that’s known as a Noreaster. As it encountered the massive low pressure system filled with cold air from Canada it became a hybrid superstorm.
It sounds like the beginning of a far-fetched disaster movie but these are the types of events that are becoming more frequent as the climate changes.
Here’s what the Weather Channel’s Bryan Norcross wrote about this in a Facebook post Oct. 26. “The freak part is that a hurricane happens to be in the right place in the world to get sucked into this doubled-back channel of air and pulled inland from the coast.” He continues. “And the double-freak part is that the upper-level wind, instead of weakening the storm and simply absorbing the moisture — which would be annoying enough — is merging with the tropical system to create a monstrous hybrid vortex. A combination of a hurricane and a nor’easter.”This superstorm was able to set up when a common late-season hurricane and a common low pressure system from the Arctic started moving on a collision course with one another. While some scientists see the connection to Arctic melting, others see this as a freak, once-in-a-lifetime storm caused by a confluence of events.
Martin Hoerling from NOAAs Earth Science Research Laboratory says, “Great events, like this meteorological one, can happen with little cause. Individually, neither the tropical storm nor the extra-tropical storm that embraced it, were unusual. What makes this a rare, perhaps once in a lifetime event, is the fortuity of their timely intersection.”
NOAAs James Overland doesn’t see the Arctic connection but does say, “What was highly unusual to me was the slowing down of the jet stream that normally turns hurricanes out to sea, allowing Sandy to make direct landfall.”
As the pictures of massive devastation pour in from the hardest hit areas following Super Storm Sandy some are hoping that this horrific weather event will get people talking about climate change in a meaningful way, focusing on how to mitigate the worst scenarios and ultimately how to adapt to a world where extreme events–whether from tornado outbreaks, mammoth storms, droughts, wildfires or floods–are no longer outliers but the norm.
Despite the almost unfathomable havoc that Sandy wreaked several scientists think that this super storm could have actually been worse.
Even days after the hurricane made landfall in New Jersey, morphed into a hybrid storm and moved inland, the remnants are still churning over western Pennsylvania. Pittsburgh has been pounded by swirling rain and wind for two days as the storm stalled out over the area.
If the cold low pressure system from the Arctic had moved a little to the east then the storm would have stalled over New York City or New Jersey, compounding the devastation exponentially.
While the live news coverage and the scenarios that are playing out for 23 states in the storm’s path sound like fictitious emergency planning drills the pictures, the stories and the power of mother nature are quite real.
Now it’s time to face another reality. The world’s climate is changing. The change is underway and starting to become visible in the starkest of ways. The question remains: what are we going to do about it?
Francis and Vavrus say, “As the Arctic sea ice cover continues to disappear and the snow cover melts ever earlier over vast regions of Eurasia and North America, it is expected that large-scale circulation patterns throughout the northern hemisphere will become increasingly influenced by Arctic amplification.” In other words, rapid Arctic warming is expected to exert a growing influence on the weather far beyond the Arctic.
Environmentalist Bill McKibben says that Superstorm Sandy ought to be a way for us all to start talking about climate change. He says, “This is an absolutely unprecedented storm and this entire year should be a serious wake-up call.”