Birds sensed severe storms and fled before tornado outbreak

Golden-winged warblers apparently knew in advance that a storm that would spawn 84 confirmed tornadoes and kill at least 35 people last spring was coming, according to a report in the Cell Press journal Current Biology on December 18. The birds left the scene well before devastating supercell storms blew in.

The discovery was made quite by accident while researchers were testing whether the warblers, which weigh "less than two nickels," could carry geolocators on their backs. It turns out they can, and much more. With a big storm brewing, the birds took off from their breeding ground in the Cumberland Mountains of eastern Tennessee, where they had only just arrived, for an unplanned migratory event. All told, the warblers travelled 1,500 kilometers in 5 days to avoid the historic tornado-producing storms.

"The most curious finding is that the birds left long before the storm arrived," says Henry Streby of the University of California, Berkeley. "At the same time that meteorologists on The Weather Channel were telling us this storm was headed in our direction, the birds were apparently already packing their bags and evacuating the area."

The birds fled from their breeding territories more than 24 hours before the arrival of the storm, Streby and his colleagues report. The researchers suspect that the birds did it by listening to infrasound associated with the severe weather, at a level well below the range of human hearing.

"Meteorologists and physicists have known for decades that tornadic storms make very strong infrasound that can travel thousands of kilometers from the storm," Streby explains. While the birds might pick up on some other cue, he adds, the infrasound from severe storms travels at exactly the same frequency the birds are most sensitive to hearing.

The findings show that birds that follow annual migratory routes can also take off on unplanned trips at other times of the year when conditions require it. That's probably good news for birds, as climate change is expected to produce storms that are both stronger and more frequent. But there surely must be a downside as well, the researchers say.

"Our observation suggests [that] birds aren't just going to sit there and take it with regards to climate change, and maybe they will fare better than some have predicted," Streby says. "On the other hand, this behavior presumably costs the birds some serious energy and time they should be spending on reproducing." The birds' energy-draining journey is just one more pressure human activities are putting on migratory songbirds.

In the coming year, Streby's team will deploy hundreds of geolocators on the golden-winged warblers and related species across their entire breeding range to find out where they spend the winter and how they get there and back.

"I can't say I'm hoping for another severe tornado outbreak," Streby says, "but I am eager to see what unpredictable things happen this time."

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Offshore wind farms could tame severe weather before they achieve land

Computer simulations by Professor Mark Z. Jacobson have proven that offshore wind farms with 1000's of wind generators might have sapped the energy of three real-existence severe weather, considerably lowering their winds and associated storm surge, and perhaps stopping vast amounts of dollars in damages.

Within the last 24 years, Mark Z. Jacobson, a professor of civil and environment engineering at Stanford, continues to be creating a complex computer model to review polluting of the environment, energy, climate and weather. A current use of the model is to simulate the introduction of severe weather. Another is to figure out how much energy wind generators can extract from global wind power.

Considering these recent model studies and as a direct consequence of severe weather Sandy and Katrina, he stated, it had been natural to question: What can happen if your hurricane experienced a sizable variety of offshore wind generators? Would the power extraction because of the storm spinning the turbines' rotor blades slow the winds and diminish the hurricane, or would the hurricane destroy the turbines?

So he worked out developing the model further and replicating what could happen if your hurricane experienced a massive wind farm stretching many miles offshore and across the coast. Amazingly, he discovered that the wind generators could disrupt a hurricane enough to lessen peak wind speeds by as much as 92 miles per hour and reduce storm surge by as much as 79 percent.

The research, carried out by Jacobson, and Cristina Archer and Willett Kempton from the College of Delaware, was released online in Character Global Warming.

The scientists simulated three severe weather: Sandy and Isaac, which struck New You are able to and New Orleans, correspondingly, this year and Katrina, which devastated New Orleans in 2005.

"We discovered that when wind generators can be found, they decelerate the outer rotation winds of the hurricane," Jacobson stated. "This feeds to decrease wave height, which reduces movement of air toward the middle of the hurricane, growing the central pressure, which slows the winds from the entire hurricane and disappears it faster."

Within the situation of Katrina, Jacobson's model says a range of 78,000 wind generators from the coast of recent Orleans might have considerably destabilized the hurricane prior to it made landfall.

Within the computer model, when Hurricane Katrina arrived at land, its simulated wind speeds had decreased by 36-44 meters per second (between 80 and 98 miles per hour) and also the storm surge had decreased by as much as 79 percent.

For Hurricane Sandy, the model forecasted a wind speed reduction by 35-39 meters per second (between 78 and 87 miles per hour) and around 34 percent reduction in storm surge.

Jacobson appreciates that, within the U . s . States, there's been political potential to deal with setting up a couple of hundred offshore wind generators, not to mention hundreds of 1000's. But he thinks you will find two financial incentives that may motivate this type of change.

The first is the decrease in hurricane damage cost. Damage from severe severe weather, triggered by high winds and storm surge-related flooding, can encounter the vast amounts of dollars. Hurricane Sandy, for example, triggered roughly $82 billion in damage across three states.

Second, Jacobson stated, the wind generators would purchase themselves in the long run by producing normal electricity yet still time reducing polluting of the environment and climatic change, and supplying energy stability.

"The turbines may also reduce damage if your hurricane comes through," Jacobson stated. "These 4 elements, each by themselves, lessen the cost to society of offshore turbines and really should be adequate to motivate their development."

An alternate arrange for safeguarding seaside metropolitan areas involves building massive seawalls. Jacobson stated that although these might stop bad weather surge, they would not impact wind speed substantially. The price of these, too, is important, with estimations running between $10 billion and $40 billion per installation.

Current turbines can withstand wind speeds as high as 112 miles per hour, which is incorporated in the selection of a category two to three hurricane, Jacobson stated. His study indicates that the existence of massive turbine arrays will probably prevent hurricane winds from reaching individuals speeds.

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