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Why it's so dangerous to walk through floodwaters
Floodwaters might not immediately look dangerous, but they can put you at risk of injuries, diseases and exposure to hazardous materials.
Disasters make 14 million people homeless each year.
About 14 million people are being made homeless on average each year as a result of sudden disasters such as floods and storms, new figures show.
Eight of the ten countries with the highest levels of displacement and housing loss are in South and Southeast Asia
By Adela Suliman
LONDON, Oct 12 (Thomson Reuters Foundation) - About 14 million people are being made homeless on average each year as a result of sudden disasters such as floods and storms, new figures show.
The risk of displacement could rise as populations swell and the impacts of climate change become more severe, said a report issued on Friday by the United Nations Office for Disaster Risk Reduction (UNISDR) and the Geneva-based Internal Displacement Monitoring Centre (IDMC).
Earthquakes, tsunamis, floods and tropical cyclones are the main disasters forecast to uproot large numbers of people, with countries in Asia, home to 60 percent of the world's population, hit particularly hard, according to modelling by the agencies.
Eight of the ten countries with the highest levels of displacement and housing loss are in South and Southeast Asia.
They include India, where an average of 2.3 million people are forced to leave their homes annually, and China with 1.3 million people uprooted each year, found the report, released on the International Day for Disaster Reduction.
The numbers exclude those evacuated ahead of a threat, and people displaced by drought or rising seas.
Russia and the United States also feature as countries where disasters could cause large-scale homelessness, unless significant progress is made on managing disaster risk, the study said.
"The findings underline the challenge we have to reduce the numbers of people affected by disasters," said Robert Glasser, the U.N. secretary-general's special representative for disaster risk reduction.
"Apart from death or severe injury in a disaster event, there is no more crushing blow than the loss of the family home," he added in a statement.
The most devastating floods to hit South Asia in a decade killed more than 1,400 people this year, and focused attention on poor planning for disasters, as authorities struggled to assist millions of destitute survivors.
Refugees and people uprooted in their own countries are already at record-high numbers, said IDMC director Alexandra Bilak. The new model goes some way towards predicting the risk of disaster-related displacement, which is an "urgent, global priority", she noted.
It is also intended to help urban planners in hazard-prone towns and cities who must consider the safety and durability of built-up areas and the threats to millions living there. Justin Ginnetti, head of data and analysis at the IDMC, told the Thomson Reuters Foundation there was a strong correlation between the risk of being uprooted by a disaster and residing in a rapidly urbanising location.
With the poor often living on the outskirts of cities, on flood plains or along river banks, Ginnetti said better urban planning could make them less vulnerable.
He contrasted Japan and the Philippines, which have roughly the same number of people exposed to cyclones. Japan builds more robust housing and so faces far less displacement in a disaster than the Philippines, where homes are less able to withstand shocks, he said.
"We don't want people to think of disaster displacement as some kind of inevitable act of God - this is not (a) necessary outcome every time there's heavy rainfall," he said.
By Adela Suliman
LONDON, Oct 12 (Thomson Reuters Foundation) - About 14 million people are being made homeless on average each year as a result of sudden disasters such as floods and storms, new figures show.
The risk of displacement could rise as populations swell and the impacts of climate change become more severe, said a report issued on Friday by the United Nations Office for Disaster Risk Reduction (UNISDR) and the Geneva-based Internal Displacement Monitoring Centre (IDMC).
Earthquakes, tsunamis, floods and tropical cyclones are the main disasters forecast to uproot large numbers of people, with countries in Asia, home to 60 percent of the world's population, hit particularly hard, according to modelling by the agencies.
Eight of the ten countries with the highest levels of displacement and housing loss are in South and Southeast Asia.
They include India, where an average of 2.3 million people are forced to leave their homes annually, and China with 1.3 million people uprooted each year, found the report, released on the International Day for Disaster Reduction.
The numbers exclude those evacuated ahead of a threat, and people displaced by drought or rising seas.
Russia and the United States also feature as countries where disasters could cause large-scale homelessness, unless significant progress is made on managing disaster risk, the study said.
"The findings underline the challenge we have to reduce the numbers of people affected by disasters," said Robert Glasser, the U.N. secretary-general's special representative for disaster risk reduction.
"Apart from death or severe injury in a disaster event, there is no more crushing blow than the loss of the family home," he added in a statement.
The most devastating floods to hit South Asia in a decade killed more than 1,400 people this year, and focused attention on poor planning for disasters, as authorities struggled to assist millions of destitute survivors.
Refugees and people uprooted in their own countries are already at record-high numbers, said IDMC director Alexandra Bilak. The new model goes some way towards predicting the risk of disaster-related displacement, which is an "urgent, global priority", she noted.
It is also intended to help urban planners in hazard-prone towns and cities who must consider the safety and durability of built-up areas and the threats to millions living there. Justin Ginnetti, head of data and analysis at the IDMC, told the Thomson Reuters Foundation there was a strong correlation between the risk of being uprooted by a disaster and residing in a rapidly urbanising location.
With the poor often living on the outskirts of cities, on flood plains or along river banks, Ginnetti said better urban planning could make them less vulnerable.
He contrasted Japan and the Philippines, which have roughly the same number of people exposed to cyclones. Japan builds more robust housing and so faces far less displacement in a disaster than the Philippines, where homes are less able to withstand shocks, he said.
"We don't want people to think of disaster displacement as some kind of inevitable act of God - this is not (a) necessary outcome every time there's heavy rainfall," he said.
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'Katrina brain': The invisible long-term toll of megastorms.
Long after a big hurricane blows through, its effects hammer the mental-health system.
Bryan Tamowski for POLITICO
The Agenda
AGENDA 2020
'Katrina brain': The invisible long-term toll of megastorms
Long after a big hurricane blows through, its effects hammer the mental-health system.
By CHRISTINE VESTAL 10/12/2017 05:10 AM EDT
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NEW ORLEANS — Brandi Wagner thought she had survived Hurricane Katrina. She hung tough while the storm’s 170-mph winds pummeled her home, and powered through two months of sleeping in a sweltering camper outside the city with her boyfriend’s mother. It was later, after the storm waters had receded and Wagner went back to New Orleans to rebuild her home and her life that she fell apart.
“I didn’t think it was the storm at first. I didn’t really know what was happening to me,” Wagner, now 48, recalls. “We could see the waterline on houses, and rooftop signs with ‘please help us,’ and that big X where dead bodies were found. I started sobbing and couldn’t stop. I was crying all the time, just really losing it.”
Twelve years later, Wagner is disabled and unable to work because of the depression and anxiety she developed in the wake of the 2005 storm. She’s also in treatment for an opioid addiction that developed after she started popping prescription painkillers and drinking heavily to blunt the day-to-day reality of recovering from Katrina.
More than 1,800 people died in Katrina from drowning and other immediate injuries. But public health officials say that, in the aftermath of an extreme weather event like a hurricane, the toll of long-term psychological injuries builds in the months and years that follow, outpacing more immediate injuries and swamping the health care system long after emergency workers go home and shelters shut down.
That’s the rough reality that will soon confront regions affected by this year’s string of destructive hurricanes. As flood waters recede from Hurricanes Harvey, Irma, Maria and Nate, and survivors work to rebuild communities in Texas, Florida and the Caribbean, mental health experts warn that the hidden psychological toll will mount over time, expressed in heightened rates of depression, anxiety, post-traumatic stress disorder, substance abuse, domestic violence, divorce, murder and suicide.
Brandi Wagner's home in Lafitte, La., left, and the nearby bayou, Bayou Barataria, right. Below, sandbags line the street across from Wagner's home as Hurricane Nate approached earlier this month. | Bryan Tamowski for POLITICO
Renée Funk, who manages hurricane response teams for the Centers for Disease Control and Prevention, says it has become clear since Katrina that mental illness and substance abuse aren’t just secondary problems—they are the primary long-term effect of natural disasters.
“People have trouble coping with the new normal after a storm,” Funk said. “Many have lost everything, including their jobs. Some may have lost loved ones, and now they have to rebuild their lives. They’re faced with a lot of barriers, including mental illness itself,” she said.
In New Orleans, doctors are still treating the psychological devastation of Katrina. More than 7,000 patients receive care for mental and behavioral health conditions just from the Jefferson Parish Human Services Authority, a state-run mental health clinic in Marrero, just across the Mississippi River from New Orleans. At least 90 percent of the patients lived through Katrina and many still suffer from storm-related disorders, according to medical director and chief psychiatrist Thomas Hauth, who adds that he and most of his fellow clinicians also suffer from some level of long-term anxiety from the storm.
“Every year about this time, I start checking the National Weather Service at least three times a day,” he said.
These long-term mental health effects of extreme weather are a hidden public health epidemic, one that is expected to strain the U.S. health care system as the intensity and frequency of hurricanes, tornadoes, floods, wildfires, earthquakes and other natural disasters increase in coming decades because of global warming and other planetary shifts.
With climatologists promising more extreme weather across the country, mental and behavioral health systems need to start preparing and expanding dramatically or demand for treatment of the long-term psychological effects of future natural disasters will vastly outstrip the supply of practitioners, said Georges Benjamin, director of the American Public Health Association.
Dr. Thomas Hauth, a psychiatrist, in his office at the Jefferson Parish Human Services Authority in Marrero, La., where he treats residents still suffering from anxiety, post-traumatic stress disorder and other mental disorders caused or exacerbated by Hurricane Katrina. Hauth and his colleagues also report post-storm anxiety and other conditions. | Bryan Tamowski for POLITICO
“On a blue sky day, our mental health resources are stretched,” said Carol North, researcher and professor of psychiatry at University of Texas Southwestern in Dallas. “There’s a lot we don’t know yet, but common sense tells us that more disasters and worse disasters will lead to worse psychological effects.”
”Katrina brain”
For climate change believers, this year’s string of record-breaking Atlantic hurricanes was just a warm-up for what scientists predict will be more frequent extreme weather events in the future.
When an entire city experiences a significant trauma at the same time, as New Orleans did during Katrina and Houston did during Harvey, it can push a lot of people over the edge, said Eric Kramer, another doctor who worked in the Jefferson Parish clinic: “Some people can rely on their inner strength and resilience to get through it, but others can’t.”
In the aftermath of Katrina, many survivors struggled with short-term memory loss and cognitive impairment, a syndrome dubbed “Katrina brain,” according to a report by Ken Sakauye, a University of Tennessee professor of psychiatry who was at Louisiana State University at the time.
Even though more than half the population of New Orleans had evacuated, psychiatric helpline calls increased 61 percent in the months after Katrina, compared with the same period before the storm, death notices increased 25 percent, and the city’s murder rate rose 37 percent, Sakauye wrote.
A year after Katrina, psychiatrist James Barbee reported that many of his patients in New Orleans had deteriorated from post-Katrina anxiety to more serious cases of depression and anxiety. "People are just wearing down," Barbee said. "There was an initial spirit about bouncing back and recovering, but it's diminished over time, as weeks have become months.”
In a longitudinal study comparing the mental health of low-income single moms in New Orleans before and after Katrina, one in five participants reported elevated anxiety and depression that had not returned to pre-storm levels four years later, said Jean Rhodes, study co-author and professor of psychiatry at University of Massachusetts Boston.
Hurricane Katrina killed 1,800 people in 2005, and left behind massive property damage. But publiGetty Imagesc health officials are learning that the longest-lasting damage of several storms is psychological. | Getty Images
For a smaller percentage of people in the study, particularly people with no access to treatment, symptoms of anxiety developed into more serious, chronic conditions such as post-traumatic stress disorder, the researchers found.
These aren’t cheap conditions to treat. One study cited by the CDC estimated the cost of treating even the short-term effects of anxiety disorders at more than $42 billion annually; double-digit regional leaps in rates of anxiety could cause serious financial strain to patients, employers, insurers and the government.
Vicarious reactions
Some damage can take place outside the storm-hit region. Even for people who have never experienced the raging winds, floods and prolonged power outages of a hurricane, this season’s repeated images of people struggling against the storms on television and other news and social media created unprecedented levels of anxiety and depression nationwide, said Washington, D.C., psychiatrist and environmental activist Lise Van Susteren.
“There is a vicarious reaction. When we see people flooded out of their homes, pets lost, belongings rotting in the streets, and people scared out of their wits, we experience an empathic identification with the victims,” she said.
Brandi Wagner pulls out the medications she must take on a daily basis to control a range of storm-related disorders including anxiety, depression, bipolar disorder, and an addiction to opioids. | Bryan Tamowski for POLITICO
“People come in saying they can’t sleep, they’re drinking too much, they’re having trouble with their kids, their jobs or their marriages are falling apart. They may not know where the anxiety is coming from, but everyone is affected by the stress of climate change.”
The same kind of vicarious reactions were documented after the Sept. 11, 2001, terrorist attacks in New York and Washington and after Hurricane Katrina, particularly in children, said Columbia University pediatrician and disaster preparedness expert Irwin Redlener.
“The mental health effects of natural disasters are really important and vastly overlooked, not only acutely but over the long term,” he said.
Everyone who lives through a major storm experiences some level of anxiety and depression. But for low-income people and those without strong social supports, the symptoms are much worse, said Ronald Kessler, an epidemiologist and disaster policy expert at Harvard Medical School. The same is true for people who already suffered from mental illness or drug or alcohol addiction before the disaster occurred.
Repeated exposure to weather disasters is another risk factor for mental and behavioral disorders. Hurricane Katrina decimated New Orleans on Aug. 29, 2005, followed by Hurricane Rita less than a month later. Three years after that, Hurricane Gustav hit the Louisiana coast, followed by Hurricane Ike two weeks later.
In September, many who had fled Hurricane Katrina and resettled in Houston had to relive the same horrors all over again, putting them at higher risk for long-term mental health problems.
TOP LEFT: Wagner in her backyard. TOP RIGHT: Wagner's medications. BOTTOM LEFT: Wagner shows off a photo of her son, Sgt. Aaron Briggs, receiving his sergeant badge in a photo on her phone. BOTTOM RIGHT: Wagner's daughter, Jessica Briggs, her grandson, Jeremy Goudeau Jr., and her daughter, Kristina Briggs, at her home in Lafitte, La.. | Bryan Tamowski for POLITICO
But perhaps the greatest risk of adverse mental health reactions to storms occurs when an entire community like New Orleans’ Lower Ninth Ward is so completely destroyed that people can’t return to normal for months or years, if ever. For those who left and went to live in Houston, Atlanta and other far-flung cities, the dislocation and loss of community was equally harmful, researchers say.
“People are only physically and mentally resilient to a point and then they are either irretrievably injured or they die,” Kessler said. If storms intensify in the future, the kind of devastation parts of New Orleans experienced could become more common, he said.
Psychiatric First Aid
In the past decade, first responders and public health workers began training in a type of mental health first aid that research has shown to be effective in lowering anxiety and reducing the risk that the traumas experienced during a storm will lead to serious mental illness.
Using evidence-based techniques, rescue workers reassure storm survivors that feelings of sadness, anger and fear are normal and that they are likely to go away quickly. But when survivors complain that they’ve been crying nonstop, haven’t slept for days or are having suicidal thoughts, rescue workers are trained to make sure they get more intensive mental health care immediately.
In Houston, for example, teams of doctors, nurses, mental health counselors and other health care professionals offered both physical and mental health services at clinics set up in every storm shelter. The city’s emergency medical director, Davie Persse, said the clinics were so successful that local hospital emergency departments reported no surges in patients with psychiatric distress or minor injuries.
Forced evacuation, whether temporary or permanent, can also trigger psychological problems for people confronted by natural disasters. | Wikimedia Commons
Another important factor in reducing the psychological impacts of a storm is avoiding secondary traumas like being stranded for weeks in the convention center in New Orleans, said Sarah Lowe, a co-author of the Katrina study who teaches psychology at Montclair University in New Jersey. “Repeated traumas can pile up almost the way concussions do.”
“What I’m seeing in Harvey and Irma is there’s more mitigation of secondary trauma,” Lowe said. People were allowed to take their pets to the shelters with them, for example. In Katrina, survivors either had to leave their pets behind or stay in their homes and be more exposed to physical and mental dangers.
Evacuation and relocation
Some public health experts say that we need to start thinking of longer-term solutions to the longer-term problem of severe weather; instead of trying to treat post-storm psychological damage, we should avoid it in the first place by persuading residents to move out of storm-prone areas.
“We do a great job with preparedness and response to hurricanes in this country. It’s an amazing accomplishment,” said Mark Keim, an Atlanta-based consultant who works with the CDC and the National Center for Disaster Medicine and Health. “But as climate change progresses over the next one hundred years, what are we going to do—respond, respond, respond? We can’t afford that anymore.”
According to Keim, much of the rest of the world is already taking that approach:
“Hurricanes can’t be prevented, but by refusing to rebuild in flood plains and developing the infrastructure needed to reduce inland flooding and coastal surges, we can avoid much of the human exposure to the coming storms. That’s where the world is right now in disaster management. Preparedness and response are older approaches.”
Climate change experts agree. To avoid increasing loss of lives from the mega storms expected in the decades ahead, large coastal populations should relocate, researchers say. Mathew Hauer, a demographer at the University of Georgia, recently found that a predicted 6-foot rise in sea levels by 2100 would put 13 million people in more than 300 U.S. coastal counties at risk of major flooding.
But relocating large populations has its own risks. For the hundreds of thousands of New Orleans residents who rebuilt their lives far from home after Katrina, the loss of social ties and the stress of adapting to new surroundings also took a heavy psychological toll, according to recent research at the University of California.
There’s another problem with relocating people from coastal regions. It’s not just hurricanes that are expected to plague the planet as the climate shifts. Wildfires, droughts, inland flooding, tornadoes, earthquakes and other natural disasters are also expected to increase in frequency and intensity, making it hard to find a safe place to put down new roots.
“Whether people decide to stay or decide to move, which means giving up a way of life, the long-term psychological costs of climate change appear to be inevitable,” Harvard’s Kessler said. “We can expect a growing number of people to have to face that dilemma. They’ll be affected by extreme weather one way or another, and they will need psychological help that already is in short supply.”
Christine Vestal is a reporter for Stateline, a nonprofit journalism project funded by the Pew Charitable Trusts.
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Mid-air turbulence set to triple due to climate change, scientists warn.
Commercial airliners will be buffeted by up to three times more turbulence in future decades, according to a new report.
Commercial airliners will be buffeted by up to three times more turbulence in future decades, according to a new report.
Experts have warned the risk of mid-air injuries will rise and passengers can expect to spend more time confined to their seats with the seatbelt sign switched on due to rougher skies disturbed by climate change.
On some popular routes for UK travellers, such as transatlantic flights, instances of severe turbulence will increase by 180 per cent, while over Europe the rate is set to worsen by 160 per cent.
Scientists had already noticed that so-called clear-air turbulence (CAT) was on the rise, however the new study by the University of Reading is the first to come up with a comprehensive mathematical model predicting long-term global conditions.
It estimates that by 2050 the rate of inflight injuries will have almost tripled in line with the increased volume of turbulence.
The research team called for better forecasting systems allowing cabin crew to get their passengers seated and belted in time.
“Air turbulence is increasing across the globe, in all seasons and at multiple cruising altitudes,” said Paul Williams, Professor of Atmospheric Science at Reading, who led the new study.
“This problem is only going to worsen as the climate continues to change.”
CAT is the most troublesome type faced by airliners because it is invisible and cannot be detected on radar.
Global warming is increasing the phenomenon by strengthening wind instabilities at high altitudes in the jet streams and by making pockets of rough air stronger and more frequent.
Even severe turbulence is all but incapable of threatening the survival of a commercial aircraft, however it can cause injury to those on board.
In June, 20 people were injured, including some with broken bones and head wounds, when a China Eastern Airlines flight from Paris to South West China struck heavy turbulence.
The overall number of casualties recorded globally each year is in the low hundreds, however experts believe this is due to under-reporting of minor injuries and the true number is significantly higher.
Last month the manufacturer Boeing announced it was preparing to test a new laser technology allowing pilots to detect CAT up to ten miles away, although given the 550 mph cruising speed of most passenger jets, this would only give about 60 seconds’ notice.
“Unless aviation meteorologists become better at forecasting patches of turbulence, passengers will face increased discomfort levels from in-flight bumpiness and an increased risk of injury,” said Professor Williams.
“Air travellers can expect the amount of time they spend flying through turbulence confined to their seats to double or maybe even treble on some routes.”
Published in the journal Geophysical Research Letters, the study predicted that severe turbulence over North America will increase by 110 per cent from 2050, 90 per cent over the North Pacific and 60 per cent over Asia.
The model also include the first turbulence predictions for the Southern Hemisphere and tropical regions of the planet, estimating an increase in severe turbulence over South America of 60 per cent, and Australia and Africa of 50 per cent.
Aircraft are currently thought to spent about three per cent of their cruising time in light intensity CAT, and about 1 per cent in turbulence of moderate intensity.
Dr Manoj Joshi, who co-authored the research from the University of East Anglia, said: “This study is another example of how the impacts of climate change can be felt through the circulation of the atmosphere, not just through the increases in surface temperature itself.”
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Divided US solar sector spars over trade relief at hearing.
U.S. solar manufacturers on Tuesday asked federal trade officials to impose tariffs on cheap foreign-made panels, clashing with companies who rely on those products to build low-priced projects that can compete with gas and coal.
(Reuters) - U.S. solar manufacturers on Tuesday asked federal trade officials to impose tariffs on cheap foreign-made panels, clashing with companies who rely on those products to build low-priced projects that can compete with gas and coal.
In a closely-watched case, the U.S. International Trade Commission is set to recommend measures to prop up the small domestic solar manufacturing industry after it ruled unanimously last month that producers have been harmed by imports.
It must deliver its report by Nov.13 to President Donald Trump, who will then decide how to proceed.
The outcome could have a major impact on the price of solar power in the United States and determine whether the renewable energy technology can compete with dominant fossil fuels.
Suniva and SolarWorld, which are both foreign-owned but manufacture panels in the United States, asked for four years of tariffs on all solar cells and panels made overseas, plus either a price floor on panels or an import quota.
“Tariffs alone will not remedy the serious injury you found,” Suniva attorney Matthew McConkey told the commission.
In documents filed last week, Suniva asked for a tariff of 25 cents per watt on solar cells and 32 cents per watt on panels. The manufacturer is also seeking a minimum price on panels of 74 cents a watt, nearly double their current cost. SolarWorld has asked for an import quota.
Existing tariffs on solar products from China and Taiwan have been insufficient to protect the domestic industry, Suniva said.
Suniva is majority owned by Shunfeng International Clean Energy and SolarWorld AG is based in Germany. Suniva filed for bankruptcy in April and soon after filed its petition with the ITC.
The Solar Energy Industries Association, the sector’s primary trade group, opposes Suniva’s petition.
SEIA argued on Tuesday that higher panel prices would hurt demand, impacting installation companies and manufacturers and leading to widespread job losses.
“These job losses are far, far in excess of any limited job gains the domestic cell and module industry might obtain based on optimistic projections,” SEIA attorney Matthew Nicely said.
SEIA suggested less radical remedies - technical assistance, job training programs, and a modest import licensing fee.
SunPower Corp Chief Executive Tom Werner testified that concerns about new tariffs had caused his company to lose “a multi-hundred million dollar opportunity” to rival First Solar Inc, which uses a technology not included in the trade case.
“We couldn’t offer price certainty and they could,” Werner said. SunPower is based in California but primarily manufactures panels in Asia.
Reporting by Nichola Groom; Editing by Sue Horton and Rosalba O'Brien
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One of the clearest signs of climate change in Hurricanes Maria, Irma, and Harvey was the rain.
Warmer temperatures are increasing the energy and moisture available to hurricanes.
As Hurricanes Harvey, Irma, and Maria plowed through unusually warm oceans this summer, each one broke records, startling even the scientists who study extreme weather.
“All of these storms went through a period where they gained strength quickly,” said James Kossin, an atmospheric scientist at the NOAA Center for Weather and Climate Prediction. “That was alarming.”
The intensity of Hurricane Maria, which made landfall on Puerto Rico as a Category 4 storm on September 20, was part of why it was so devastating to the island and its weak infrastructure, leaving Puerto Ricans in a humanitarian crisis.
But this year’s intense Atlantic storm season had another element tying its biggest events together: a monstrous, and sometimes deadly, amount of rain.
Images of the flooded metropolises of Houston, Jacksonville, and San Juan with overtopped dams, billowing sewage, and flooded homes show that torrential rain can be one of the most devastating consequences of hurricanes, especially in urban areas where concrete makes it harder for water to drain and where people can drown.
Scientists say the extreme rainfall events that feed these floods are on the rise for many parts of the world, and this year’s hurricanes fit that trend. In particular, rising temperatures in the ocean and the air alongside booming construction in vulnerable areas are fueling the increased risk from massive deluges.
Of the seven hurricanes this year so far, Harvey, Irma, and Maria stand out not just for the amount of rain they dropped, but for how fast they dished it out.
Why hurricanes under warmer conditions can dump so much rain
Downpours go hand in hand with hurricanes, since the cyclones are powered by evaporating and condensing moisture.
Warm ocean waters provide the fuel for hurricanes, and warm air causes the water to evaporate. This moisture-laden air then precipitates as rainfall during a hurricane, dissipating the heat energy from the water.
“Tropical cyclones are very, very good at converging a whole lot of heat in one place at one time,” said Kossin.
Air can hold about 7 percent more water for every degree Celsius increase in temperature, Kossin explained.
That means warmer air and warmer water could lead to larger, more intense hurricanes, which in turn lead to more rainfall. (The Saffir-Simpson scale only accounts for windspeed, but precipitation is closely linked to a storm’s intensity.) Scientists are studying these links to understand how future storms will respond to these conditions.
“Hurricanes live and die by the amount of rainfall they make out of moisture,” said George Huffman, a research meteorologist at NASA Goddard Space Flight Center.
But where that water lands depends on the speed and the course of the storm, and not all areas are equally vulnerable.
“We know that in particular that [the regions around] Houston, Louisiana, and Florida are prone to some of the most extreme precipitation events in the United States,” said Sarah Kapnick, a researcher at NOAA’s Geophysical Fluid Dynamics Laboratory. “We do see signs of precipitation extremes increasing in these regions.”
It’s challenging to make direct comparisons between extreme rainfall events since their weather systems (e.g., hurricanes, thunderstorms) behave differently, so scientists draw on several benchmarks depending on the situation.
These include the peak rate of rainfall, total volume of rain, the three-day average rainfall, and the maximum depth of rainfall. And all of these are separate from flooding, which is governed by local geography and how people use land, in addition to the rates and total amounts of rain.
“There is a difference between a 100-year rain event versus a 100-year flood event,” Kossin pointed out.
Harvey was able to dump an extraordinary quantity of rain because of how it held still over Houston
Hurricane Harvey hovered over the Gulf Coast in late August and dumped 33 trillion gallons of water on US soil, according to some estimates, and is now the wettest storm in US history.
“When a storm stalls, that has more to do with the larger scale flow fields it’s sitting in,” said Kossin. “That was just very, very bad luck.”
The total volume of rain is easier to calculate when a storm remains over a fixed area, but it much harder to suss out when hurricanes remain mobile and dump water over a wide swath of land and ocean.
NASA’s satellite measurements reported rainfall rates from Harvey as high as 5.8 inches per hour (meteorologists define “heavy rain” as greater than 0.3 inches per hour), while the National Weather Service showed that a ground-based rain gauge in Nederland, Texas, reported 60.58 inches of rainfall, a new record.
Meteorologists still have to vet this number, but if confirmed, it would best the previous record — 52 inches in Hawaii from Hurricane Hiki in 1950 — by 8 inches.
The US Geological Survey reports that flooding causes an average of $6 billion in damages and 140 fatalities each year. And this year was not an average year, with Harvey alone costing upward of $180 billion and killing more than 75.
The waters from flooding can linger for days, causing injuries, spreading disease, and hampering relief efforts. The majority of Harvey’s victims drowned after the storm, while others were delayed from life-saving care. In one case, a woman died from a flesh-eating bacterial infection after falling into the festering Harvey floodwater in her house.
Irma’s peak rain was over Cuba
Hurricane Irma, meanwhile, set a record for its sustained intensity.
One hour of 30-second #GOES16 vis imagery as Hurricane #Irma made landfall in the Florida Keys as a cat 4 with sustained winds of 130 MPH. pic.twitter.com/SWIMtbIqAP
— NASA SPoRT (@NASA_SPoRT) September 10, 2017
“Irma was a complete standout: 185 mph and stayed there for a day and half,” Kossin said. “These storms do not stay there that long.”
This intensity was matched with a firehose of rain, dumping water at 10.8 inches an hour, reaching depths of 20 inches in Cuba and 15.8 inches in Florida.
The downpour led to flooding from 23 rivers and creeks in Central and North Florida, forcing highways to close. The state reported at least seven deaths from drowning.
In Cuba, Irma’s storm surge overtopped the Havana seawall, while unrelenting rain turned the capital’s streets into rivers, killing at least 10 people .
Maria took direct aim at Puerto Rico and then regained strength
With tropical force winds reaching 230 miles from its center, Hurricane Maria completely engulfed Puerto Rico as it bisected the 100-mile wide island, picking up steam again one it was clear.
Satellite measurements already show that it poured as much as 6.44 inches of rain per hour and has left Puerto Rico shrouded in darkness.
Hurricane #Maria's Torrential Rainfall in #PuertoRico Measured By GPM IMERG 9/17/17 - 9/21/17 https://t.co/814C281kvu pic.twitter.com/CRcnMXJ5xk
— NASA Precipitation (@NASARain) September 21, 2017
The Cordillera Central mountain range that forms the spine of the island of Puerto Rico acted as a juicer for Hurricane Maria, Huffman explained, rapidly squeezing out 20 to 36 inches of rain from the cyclone.
In *less than one day* parts of Puerto Rico have received 24-36"+ of rain.
For context: Houston had 32" in *three days* during Harvey. Wow. https://t.co/5dWnxtEPTp
— Eric Holthaus (@EricHolthaus) September 21, 2017
Perhaps the worst blow from Maria was the 160 mph winds that knocked down 80 percent of the island’s power transmission lines and 85 percent of its cellphone towers, leaving people in the dark and struggling to contact each other. But the flooding from rainfall has been a hazard too, including threatening to breach Guajataca Dam in the Western part of the island, forcing hundreds to evacuate.
At least 18 fatalities have been reported in Puerto Rico so far, including two police officers who drowned.
The climate signal in deluges like these is emerging
No single weather event — even an extreme one — can be “caused” by climate change, as Vox’s David Roberts has explained in detail. And when talking about hurricanes, researchers are quite hesitant to even estimate how much climate change is to blame. Huffman said he’s not yet sure if this storm season is “unprecedented” in its ferocity.
However, rising average temperatures are definitely an important element of huge storms like Harvey, Irma, and Maria.
Warmer temperatures are driving sea level rise, which is increasing risks from the storm surges that often herald hurricanes.
Increasing heat is also warming up the ocean, and hotter air holds onto more moisture, increasing the available energy for hurricanes.
And independent of cyclones, extreme rainfall events are on the rise.
Kapnick noted that even individual rain storms can be overwhelming, like storm that drenched Baton Rouge last year with 31.39 inches of rain and three times the volume of water of Hurricane Katrina throughout Louisiana in 2005.
As the chart below shows, the amount of rain from a once-in-every-30-years rainstorm like the one that immersed Baton Rouge has gone up due to warming:
“In this region where we have known precipitation extremes, we have been able to detect an increase in precipitation extremes due to a warming climate,” Kapnick said.
And scientists are getting better at figuring out when the torrential downpours are coming.
“If you pay attention, we’ve had a really remarkable series of forecasts,” said Huffman. “For Irma, we knew four to five days in advance that there would be a sharp right turn. Twenty years ago, you wouldn’t have dreamed of doing that.”
“Everything we see is consistent with what we expect climate change to do,” Kossin said.
Instruments sometimes can’t stand up to the extreme weather they’re trying to measure
Huffman explained that researchers aim to combine different instruments to get a robust handle on rainfall.
“The gold standard is rain gauges because they physically collect the rain,” said Huffman.
The next option is ground-based radar, which covers a wider swath of the weather than rain gauges, but less directly measures rain.
But take a look at what happened to a weather radar station in Puerto Rico:
Wow, this is TJUA San Juan, Puerto Rico radar back in March, and now after Hurricane Maria. Incredible. Recent photo courtesy of @NWSSanJuan pic.twitter.com/WFzIxZBbGn
— Bryce Kintigh (@stormchasrbryce) September 24, 2017
This illustrates part of the challenge of attaching numbers to extreme weather events. Many of the systems used to track them are also vulnerable to them, leaving only indirect figures and estimates.
What’s more, both rain gauges and ground-based radar have limited ranges, leaving vast stretches of ocean where hurricanes spend most of their existence unmeasured. And when a hurricane does make landfall, gales can knock them down.
“We don’t really have anything on the surface [of the ocean] to tell us the details,” said Huffman. “When the chips are really down, sometimes satellites are the only choice.”
That means the full accounting for the rainfall from Harvey, Irma, and Maria could take months to deliver as meteorologists piece together their models with the measurements they have.
However, scientists are eagerly waiting for the dust to settle so they can confirm their suspicions about the record-breaking storms this year. The American Geophysical Union added a last-minute session for researchers to present their findings on Harvey and Irma at their December meeting.
“There’s going to be a tremendous amount of research coming out in the next few months,” Kapnick said.
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Boom and busted.
In trying to untangle a mysterious herring collapse from the aftermath of the Exxon Valdez oil spill, scientists in Prince William Sound are revealing just how resilient—and unpredictable—marine ecosystems can be.
On a cold day in June, Scott Pegau leans toward the passenger window of a Cessna floatplane and peers out at the teal waters of Prince William Sound. The glacier-rimmed pocket of seawater on the southern coast of Alaska is protected from the open ocean by a string of rugged islands. It is both moody and alluring. Clouds dally on the snowy peaks and fray against the forested hillsides. The sea is flat and frigid, except for a single row of waves lapping at the rocky shore.
Pegau aims his gaze at the shallow waters behind the breakers. After a few minutes of searching, above a deep bay on one of the outer islands, he finally spots what he’s looking for: a school of juvenile herring. Pegau can distinguish them from other schooling species by the unique way they sparkle—an effect produced by sunlight playing off their silver flanks as the fish bank and roll. Try as I might, I can’t make out any twinkling, just the inky splotch of a few tons of small fish swarming below the surface.
“Small H1,” Pegau says into the headset microphone, tucked snugly under his thick, grey mustache. That’s code for a small school of one-year-old herring. He enters the location on his computer; huddled in the back seat, I make a tick mark on the backup tally. It’s the first of dozens of schools we’ll see on our flight.
Pegau conducts these surveys every year in hopes of understanding what’s in store for the herring population in Prince William Sound. The fish mature and begin to join the spawning stock at the age of three, so the counts give scientists and managers a clue about how many adults may be coming up the pipeline. Researchers and fishers alike always hope the answer will be many. But every year for the past quarter century, they have been disappointed.
The herring population in Prince William Sound crashed in 1993, just 4 years after the Exxon Valdez oil spill released 11 million gallons of crude into these waters. The collapse put an end to an $8-million-dollar-a-year fishery, and left a hole in the middle of the marine food web. Scientists have spent years trying to understand if and how the spill played a role in the herring’s demise here, and the results have been hotly contested. All of the legal proceedings finally closed in 2015, with herring listed as an impacted species but with most herring fishers feeling poorly compensated.
Even more concerning is the fact that, unlike most species hit by the spill, the herring haven’t bounced back over the decades since. Populations of forage fish are known to boom and bust, so most scientists thought it was only a matter of time before they rebounded. But 25 years later, there’s still no sign of recovery on the horizon.
“There’s definitely a possibility that the ecosystem went through a tipping point,” says Pegau, who coordinates the herring program at the Prince William Sound Science Center, an independent research institute whose work is funded in part by money from the spill settlement. A host of factors, which scientists are still trying to untangle, could be to blame, from hungry whales to virulent disease. “There’s no one thing that’s keeping them down,” Pegau says. “I think pretty much everyone is convinced of that.”
The herring mystery is a maddeningly concrete example of the often-abstract interconnectedness of nature, which frequently gives ecosystems their resilience, but can sometimes make them rebellious. If jolted a particular way—for instance, by a human-caused disaster or an environmental shift—an ecosystem may not revert to its original state. Instead it may settle into a new normal, leaving both the organisms and economies that rely on it reeling.
But the herring in Prince William Sound may also hold clues to long-standing questions about why ecosystems change, and how they cause fish populations to flourish or founder. After 25 years of research, scientists have collected reams of data on the herring, and half a dozen hypotheses to explain their plight. The data have yet to reveal satisfying answers, but what researchers learn about ecological resilience—and the true value of a species—could have ramifications well beyond Alaska’s shores.
After a few hours of surveying, the floatplane splashes down in Eyak Lake, which fills the Y-shaped valley separating Cordova from the looming peaks of the Chugach Mountains. “We survived another one,” jokes the pilot, as we taxi to a floating dock and unload. Pegau makes plans to fly again the next day, and we climb into the well-worn seats of his white F-250 for the short drive back to town.
Cordova is a no-frills community on the far eastern edge of Prince William Sound that has weathered its share of ups and downs. It was established in 1906 as the seaport from which to ship vast quantities of copper mined in Kennecott, 200 miles inland. When the mine closed in 1938, Cordova fell back on its reputation as the self-proclaimed razor clam capital of the world. But that industry went belly up on March 27, 1964—Good Friday—after a magnitude 9.2 earthquake heaved the clam beds 2 meters (6 feet) above sea level.
That left fishing and canning as the main games in town. Both revolved around salmon and herring. While the much smaller herring rarely exceed 25 centimeters (10 inches) in length, they are prized for their roe, as well as for food and bait.
But in 1989, again on Good Friday, the Exxon Valdez oil spill cast the town’s future into question once again. Many residents considered it the worst blow yet. “There’s a natural disaster, and there’s a manmade disaster,” says Sylvia Lange, a Cordova native and longtime fisher who now runs a local hotel. She has experienced both kinds of catastrophes in her life, and the two, she says, feel completely different.
The ecological impacts of the spill, by now, are legend. Despite the efforts of thousands of response workers, wildlife including sea birds and otters perished in droves. The financial impacts followed swiftly too. The cleanup effort provided some business, but tourism lagged and managers closed fisheries until they knew how the spill had affected fish populations. Meanwhile, for unrelated reasons, the price of pink salmon tanked. “Cordova was in a deep, deep depression,” Lange says, “not only psychologically but economically.”
At first, it seemed like the herring made it out unscathed. The Alaska Department of Fish and Game reopened the fishery in 1990, and in the two years that followed, herring fishers had some of their best seasons on record. But when the spring of 1993 rolled around, the herring all but disappeared. The population dropped from more than 100,000 metric tons (110,000 U.S. tons) to less than 30,000 (33,000 U.S. tons).
The crash devastated a community still coping with disaster. John Renner, a long-time Cordova fisher and chairman of the herring division at Cordova District Fishermen United, says the spring herring roe harvest was a staple of Cordova’s economy. “The whole town depended on it for the first shot of revenue of the season,” Renner says “People paid their taxes, got out of debt, that type of stuff.” For many, it was a big part of their livelihood; Renner once made a quarter of his annual income off of herring roe, and just talking about the collapse still makes him angry. A draft report commissioned by the science center estimates that, in total, losing the herring has cost Cordova almost $200 million and the region nearly $1 billion.
The passage of time has done little to settle questions about what caused the herring crash. Initially, many scientists doubted whether the oil spill could have caused a decline four years later. Some early studies also suggested the impact of the oil was minimal, including those by Walt Pearson, then a fisheries biologist with Battelle Marine Sciences Laboratory whose work was funded by Exxon. Pearson’s research found that adult herring could only have been exposed to low levels of oil for a short window of time, and that there had been little overlap between oiled beaches and herring spawning grounds. “The effects were quite localized,” Pearson says. He concluded that the biggest factor contributing to the crash was that there were too many herring and not enough food, due to a natural shift in ocean conditions.
Many fishers didn’t buy that. “Anyone with half a brain would figure out it was oil,” says Jerry McCune, president of Cordova District Fishermen United, a union-turned-non-profit advocacy organization. The herring spawn occurred just weeks after the spill, and McCune, Renner, and others think that the oil devastated the cohort of herring born in 1989. They say the failure of those fish to show up in 1993 accounted for the collapse.
But survey data collected during the crash suggest that it affected fish of all ages, says Pegau, not just the young ones. And a recent statistical analysis found little evidence for any direct impacts of the spill. Instead, Pegau and others think that if the oil did play a role in the collapse, it probably did so by weakening the herring, or the food sources upon which they depend, making it easier for something else to do them in.
The prime suspect, in Pegau’s estimation, is a disease called viral hemorrhagic septicemia (VHS). While there was no official monitoring program then, fishers and scientists saw signs of VHS in 1993. “It can take a population down in a real big hurry,” Pegau says. As the name implies, fish with VHS hemorrhage and can die from organ failure. The disease spreads quickly through herring’s dense schools or when fishers corral them into an enclosure to harvest their spawn, as local fishers were doing around the time of the spill. Some researchers think that this practice, called pounding, combined with the high herring numbers before the crash, contributed to a deadly outbreak of VHS.
But the risk of an outbreak could have been exacerbated by the spill, too. Fish embryos that don’t die when exposed to oil may carry genetic scars, particularly in something called the aryl hydrocarbon receptor gene. “It turns out that that gene gets completely knocked out among survivors,” says Paul Hershberger, a disease ecologist with the U.S. Geological Survey. And compromising that gene may weaken the immune system in fish, potentially making them more susceptible to disease. Hershberger’s colleagues have demonstrated this effect in Atlantic killifish, and now, his team is testing it in herring.
Exposing herring embryos to oil may also cause them to develop heart defects that put them at a general disadvantage. They can’t swim as fast or as long, which makes them more likely to get eaten, says John Incardona, a toxicologist at NOAA’s Northwest Fisheries Science Center and lead author of a study on this subject published in 2015. In lab experiments, Incardona has found that developmental effects occur even when herring embryos encounter levels of pollution far below what is generally considered harmful. “We think all of us are way underestimating what the initial injury was to herring,” he says.
Richard Thorne, a fisheries scientist who recently retired from the Prince William Sound Science Center, takes issue with the idea of a delayed collapse altogether. Evidence that the herring population remained high until the 1993 crash came from the Alaska Department of Fish and Game’s population estimates, which are based on the stock assessment models the state uses to manage its fisheries responsibly and set sustainable harvests. But in 1993, Thorne started conducting acoustic surveys of the herring population, and realized his numbers lined up best with a different set of data collected by Fish and Game: observations of how many miles of shoreline were covered in herring spawn. Looking back at this pre-crash spawning record, Thorne came up with an alternative population history, which suggested that herring numbers started falling immediately after the spill. He thinks the fish died from ingesting oil and that the collapse, if there was one, resulted from allowing fishers to harvest a herring stock in the early '90s that managers didn’t yet realize was already declining.
Pegau, for one, doesn’t think scientists will ever know what actually transpired. “We’ll never be able to say one way or the other because no one was collecting data when it happened,” Pegau says. And frankly, he doesn’t really care what caused the initial collapse. The more pressing question, Pegau says, is why the herring haven’t come back.
I meet John Platt on a floating dock in the old harbor, and the first thing he says as he shakes my hand is, “Why are we still talking about herring 25 years later?” Platt is a third-generation Cordova fisher with a leathery face and the gnarled physique of a former wrestler. And he’s being coy; we both know the answer to his question.
Platt used to fish for herring, collecting them using a type of net called a purse seine to harvest roe. He gamely drives me out to see the net, which he stores 10 minutes outside of town and which is—as far as I can tell—the only piece of herring gear left in all of Cordova. “I always thought they would come back,” he says. We pull up to a rusted white pickup truck overgrown by weeds and Platt gestures toward the sorry sight before us. “This basically sums up the herring fishery.” He gets out and starts to unwrap a battered blue tarp covering a lumpy mass on the truck’s flatbed, He finally tugs free a loop of black mesh for me to see. The net—which cost about $20,000 new—still looks good decades later. After all, it’s hardly been used.
Like many, Platt was nearly destroyed by the herring collapse. Commercial fishing permits in Alaska are traded like stocks; the state issues a limited number, and fishers buy and sell them at prices that generally reflect the value of the fishery. And the seine fishery was a high-stakes gamble. Herring roe was a hot commodity and fishers like Platt jockeyed for position near schools of herring so they could scoop them up when the fishery opened, sometimes only for an adrenaline-filled 15-minute window. Before the crash, when Platt bought his seine permit, the going price was nearly a quarter of a million dollars. Today, the same permit is worth just $31,000.
Some note that’s remarkably high, given that the roe market has deflated and there have only been two modest herring harvests in Prince William Sound since the crash, in 1997 and 1998, when managers thought the fish might be making a comeback. But the permit’s unsinkable value is of little use to people like Platt, who purchased his permit with a loan from the state, and struggled to make the payments—and pay taxes—without any fish to catch. In total, those who held permits for herring in Prince William Sound took a $50 to $60 million-dollar hit in lost permit values, according to a recent economic analysis.
Platt got paid by Exxon for working on the cleanup effort immediately after the spill, but that money went straight into paying off boats and gear. To settle his permit debt, Platt ultimately had to sell off his salmon boat and turn over the payout from a class-action lawsuit against the company, which, after going before the Supreme Court in 2008, came in at a fraction of the original award. For many, though, it was too little, too late; the loss of the herring had already taken its toll. “It caused divorces, ruin, a few people killed themselves,” Platt says.
Like many, Platt thought the failure of the herring to recover might be grounds for reopening the 1991 settlement between the government and Exxon, (now ExxonMobil), which closed before the herring crashed. The settlement included $900 million in payments, in addition to criminal fines, and a clause that would make an additional $100 million dollars available for long-term impacts that weren’t considered in the original agreement. “This is textbook what it was for,” Platt says.
In 2006, government lawyers did launch an effort to file a claim under the reopener, but it was later aborted. Moreover, the claim made no mention of herring. “It’s maddening,” Platt says. But Pegau thinks there was a simple reason: Linking the fish’s poor recovery to the spill would have been a hard case to make.
Traces of oil still remain in Prince William Sound, buried a few feet in the sediment among beach pebbles and sand, but most scientists say it has little ecological impact on herring today. Indeed, if the spill had any role in the fish’s demise, it was by helping to knock the population off a cliff in the first place. Other forces have now taken over and seem to be holding the herring down. And they don’t seem to be letting up. In 2015, after what seemed like a few promising years, the herring population dropped again to around 8,000 metric tons (8,800 U.S. tons)—less than half of what it was after the crash in 1993.
“I think the system reset itself,” says Ron Heintz, a nutritional ecologist in Juneau with NOAA’s Alaska Fisheries Science Center. “We ended up in a new state that apparently doesn’t include herring.”
One factor at play is predation. Forage fish, by definition, get eaten, and herring are no exception. “It’s a critical food resource,” says Mary Anne Bishop, an ecologist at the Prince William Sound Science Center. She describes the spring spawn as a frenzied feast when the herring turn coastal waters white with eggs—each female releases about 20,000 of them each year. “It’s the whales, it’s the sea lions, the harbor seals, all the birds coming in,” she says. Predation doesn’t stop as herring age, either; dozens of species consume them throughout their life cycle.
While there may have been enough herring to fill bellies and nets when the fish were plentiful, they may now be trapped in what scientists call a “predator pit.” After everyone has had their fill, there simply aren’t enough fish left for the herring population to climb out of the hole. More young adults join the spawning stock each year, but not enough to outweigh the number being eaten.
There’s debate about which animals are doing the most damage, but humpback whales are a possible culprit. Their numbers have quintupled in Prince William Sound in recent decades as the gentle giants have recovered from whaling. Scientists say the whales here have learned to specialize in herring, sometimes banding together to trap the fish in “bubble nets” before taking turns gulping them down en masse. Studies suggest humpbacks may consume 20 to 75 percent of the spawning herring population each year—the equivalent of the fishers’ historic share and then some.
Other scientists, including Pearson, have suggested that salmon hatcheries may bear much of the blame. Starting in the late 1970s, managers began releasing hatchery-raised pink salmon into the sound, and in the 1980s, they began to ramp up the numbers. Researchers have hypothesized that young salmon may eat or compete with juvenile herring for food, while older salmon returning from the sea may eat herring of all ages.
It also appears that the herring in Prince William Sound continue to see diseases like VHS more than their neighbors. Hershberger developed a test to detect whether fish have recently encountered disease, and found consistently higher levels of exposure in Prince William Sound than in Sitka, 450 miles to the southeast. Some wonder whether, as Platt puts it, the herring here are “wimpy” because of some lingering epigenetic effect of the spill that has been passed down from generation to generation. Hershberger says no one has tested that yet. “At this point, all we can do is speculate.”
Factors like predation, competition, and disease can limit populations from the top down. But that’s only half of the story: There has also been a low supply of young herring. Researchers call this poor recruitment, and they suspect it’s the result of environmental factors limiting the population from the bottom up.
For the herring to recover, they need a few big years in close succession to overwhelm the demands of predation and escape the threat of disease. But that hasn’t happened in a long time, Pegau says. “It’s been 25 years of bad luck.” He points to sweeping natural changes in the North Pacific in 1989—the same year as the spill—as a potential turning point. The exact nature of the shift was complicated, with some parts of the ocean warming and others cooling, but the impact on marine organisms was pronounced. Across the Gulf of Alaska, animals toward the bottom of the food web, like shrimp, crab, and herring have fared poorly since, while larger fish like halibut and cod have multiplied. This apparent contradiction continues to stump Pegau. “I have yet to figure out what in the world supports them,” he says of the thriving predators.
Much of the science center’s research looks at how oceanographic conditions affect herring in hopes of understanding why the tide has turned against them in recent decades. Among other things, that involves tracking where currents carry larvae, determining which environments young fish inhabit, and studying what controls the quantity and quality of food available to them as they store up energy to survive the harsh winter.
New research also suggests that herring recruitment may be linked to the amount of freshwater that pours into the Gulf of Alaska. High discharge years correlate with recruitment failures, says Eric Ward, a statistician at the Northwest Fisheries Science Center who led the study, published earlier this year. The mechanism, though still unclear, may have to do with how freshwater from rainfall and melting ice affects the strength and timing of the spring plankton bloom—the flurry of photosynthesis that kickstarts the entire ecosystem every year. In recent decades, there have been fewer years with extremely low runoff, which correlate with upticks in herring recruitment—what Ward calls “herring baby booms.” And as climate change melts glaciers and messes with rainfall patterns, the trend may continue.
These oceanographic factors may help explain why herring recruitment has also been weak in other parts of Alaska since the early 1990s. The reason places like Sitka still have a healthy herring fishery despite these changes, Pegau says, may simply be that the population there never crashed in the first place.
Scientists hope that figuring out what’s going on with herring will shed light on bigger questions about what fish need for successful recruitment—a problem that has stumped researchers for decades. Trevor Branch, a fisheries scientist at the University of Washington who studies the herring, says it’s possible that a whole host of things have to line up for successful recruitment: the right water temperatures, the right salinity, and abundant food, among them.
If scientists are to have any shot at figuring out how these fit together, they need lots of data collected over many years. And the research sparked by the Exxon Valdez oil spill and the subsequent herring crash have furnished just that. “If ever we were able to pinpoint something, it would be with Prince William Sound herring,” Branch says.
The day of my second flight with Pegau, the weather is sublime. We head across Prince William Sound to survey its far southwestern corner. A cruise ship glides beneath us, then a cluster of salmon seiners. The small skiffs that accompany them trace lazy circles on the surface, like ripples from giant raindrops, as they loop their nets around unsuspecting fish.
We officially begin the survey in a milky, ice-flecked fjord with a reclusive glacier tucked away at its head, and follow the coastline in and out of emerald bays. In the narrow passages between Evans, Elrington, and Latouche Islands, we spot school after school of herring, clustered along the rugged shoreline. In the afternoon light, I finally see them sparkle.
Nearly a hundred years ago, these were prime fishing grounds for an earlier incarnation of the herring fishery. Fishers caught huge quantities of herring, which were reduced for oil. For five consecutive years, they brought in in an average of 40,000 tons a year, Pegau says, marveling at the scale. Catch records show that those big hauls likely drove the herring to collapse, but remarkably, they appear to have recovered in the span of just 3 or 4 years. Pegau takes this as evidence that the herring in Prince William Sound have rallied back from the brink before, like others around the world.
John Trochta, one of Trevor Branch’s graduate students at the University of Washington, has analyzed more than 50 historical herring populations across the globe, most of which have collapsed at some point. He found that the majority rebounded within a decade, but there were a few exceptions where herring numbers remained low for at least twenty years after a crash. One is in Prince William Sound; another is off the coast of Japan and southeastern Russia. There, fishers once harvested nearly a million metric tons of fish per year from the legendary Hokkaido-Sakhalin stock. But by the 1930s, perhaps due to intense fishing pressure and oceanographic changes, the stock began to decline sharply, until, by 1955, there were hardly any fish left. It’s the only herring stock yet to come back after more than 60 years. No one knows whether the same fate awaits the herring in Prince William Sound.
On my final day in Cordova, I stop by Pegau’s office at the science center—a converted icehouse perched on stilts just inside the entrance to Cordova’s harbor. From Pegau’s second-story window, he has a clear view of the bustling docks and the mountains that stand guard over town. With this year’s survey nearly complete, I ask him how it looks. “This is probably the best year we’ve seen,” he admits. He saw a lot of schools, and the schools held a lot of fish. Still, he’s reluctant to wager whether that bodes well for herring. “I’ve felt optimistic in the past; now I’m a lot more reserved.”
There’s nothing Pegau can do to help the herring. There’s no fishery to manage or acute environmental stress to relieve. That’s not the way he sees his job anyway. His goal is to understand the vulnerability and value of the fish so that other scientists and managers around the world can be better equipped to do the same. Increasingly, he and others think that the answer lies in studying an ecosystem as a whole, and how an individual species like the herring fits in. And in that regard, he is more hopeful than ever. “It’s a great puzzle,” Pegau says, his dark eyes twinkling with excitement. “One of the real joys is to see how all those pieces fit together.”
ABOUT THE AUTHOR
Julia Rosen is a freelance journalist based in Portland, Oregon. She writes about science and the environment for publications including Science, Nature, Orion, and High Country News, as well as many others. Follow her on Twitter @sciencejulia, and find more of her writing at www.julia-rosen.com.
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