a storm for the record books.

We knew this was going to get pretty big.

NARRATOR: Drawing power from ocean and air, it becomes a savage monster nearly 300 miles across.

Winds of 195 miles per hour, gusts up to 240.

Right now it's as mean as a cyclone can actually get on this planet.

This actually went off the scale.

It was a monster storm.

NARRATOR: On November 8, 2013, it becomes what could be the most powerful typhoon in history to make landfall.

This storm peaked right as it was going ashore at the Philippines.

That's the tragedy.

NARRATOR: Haiyan brings terrifying winds, torrential rain and a deadly, high-speed flood.

MAN: 20-foot storm surge came almost instantaneously, like a tsunami.

The devastation underneath this storm is unlike anything else we've seen underneath a trocal system before.

NARRATOR: In its terrible aftermath, thousands of lives lost.

We did not expect that there will be a flood that will be coming.

So many died because of the water-- neighbors, families, their families.

NARRATOR: Almost immediately the questions begin.

MAN: Why so much casualty with this typhoon?

Even our own weather center underestimated the surge.

NARRATOR: Could the deadly flood-- the storm surge-- have been predicted and catastrophe averted?

We really have a long way to go with storm surge modeling.

We've come a long way but we have a long way to go.

NARRATOR: Is Haiyan a sign of things to come, the first of a new breed of super typhoon?

MAN: Are we loading the deck towards more intense storms in the future as we provide a warmer base of ocean water for these storms to tap into?

NARRATOR: What could happen if the next killer storm strikes closer to home?

If that storm had hit the southeastern U.S., it was so powerful it would have been as much a disaster.

NARRATOR: The race is on to understand "The Killer Typhoon", right now on NOVA.

Major funding for NOVA is provided by the following: NARRATOR: Typhoons.

Explosive storms that bring torrential rain, flooding... and screaming winds.

Typhoon is the term given to hurricanes that form in the northwestern Pacific Ocean.

Hurricanes and typhoons are some the most massive storms on the planet, and we see very strong typhoons in the western Pacific more commonly than people may think.

NARRATOR: Here among the tropical islands north of Australia are some of the warmest waters on the planet, fertile breeding ground for monster storms.

By late October 2013, this region has already produced 14 typhoons.

And now unlucky number 15 begins to form, a killer whose name will soon become synonymous with devastation and heartbreaking loss... Haiyan.

Eight days before it reaches land, Haiyan begins as what's called a tropical depression, a system of thunderstorms with winds less than 30 miles an hour near Micronesia.

In Hawaii the Navy and Air Force's Joint Typhoon Warning Center monitors Pacific storms to protect U.S. military and government assets.

LT. THOMAS MILLS: We first noticed a weak disturbance southeast of Pohnpei Island, which is in the Micronesian Islands, the easternmost quadrant of the Micronesian Islands, on November 1.

We kept tracking there until we kind of saw a broad general circulation.

NARRATOR: Tropical storms form over water 80 degrees Fahrenheit or warmer.

The heat drives evaporation.

And as the rising vapor cools, it forms clouds, releasing energy as wind and rain.

The warmer the water, the more energy available to power the storm.

We knew we had a pretty rich set of ingredients, because we had warm ocean temperatures underneath it, it was pretty good circulation that had build up, so now this one's going to get pretty big.

NARRATOR: Over the next 24 hours, the storm system continues to grow in size and strength.

The rotation of the earth causes the strengthening system to spin-- counterclockwise in the Northern Hemisphere.

When wind speeds top 25 knots, about 30 miles per hour, the Navy issues its first alert.

Our first warning went out on November 3 at 1:00 a.m. Eastern Standard Time.

At that point our model fields extended out to five days, but five days out there was a lot of uncertainty.

NARRATOR: Very early on, the computers predicted that Haiyan would continue tracking over a layer of unusually thick warm water-- 86 degrees to a depth of 300 feet, more than enough fuel to fan the flames of a strong storm.

But just how strong no one could yet know.

MILLS: In the forecasting community, intensity is the difficult thing to forecast.

We knew it was going to be a strong storm.

We didn't know exactly how strong, but we knew it was going to be a big one.

NARRATOR: On November 4, 36 hours after the first warning, Haiyan becomes a typhoon, now with sustained wind speeds of more than 65 knots, about 75 miles an hour.

And it is growing stronger with alarming speed.

MILLS: At that point it was just south of Guam.

Within the next 24 hours after that, it intensified 65 knots, so it doubled in intensity.

And at that point we were tracking it at 130 knots.

130 knots is considered a super typhoon.

NARRATOR: A super typhoon... with sustained wind speeds above 150 miles an hour.

As destructive as the most notorious killer hurricanes, like Katrina, that hit New Orleans in 2005... Andrew, that hit Florida with a 17-foot storm surge in 1992... And even Camille, in 1969, with wind speeds near 200 miles an hour at landfall.

And with every passing minute, Haiyan continues to grow in size and power and looks likely to slam into one of the region's most vulnerable targets: the Philippines... More than 7,000 islands, 120,000 square miles of land, about the size of Italy but with nearly double the number of people and a population density ten times that of the U.S.

It's considered a newly industrialized country with a growing economy, but millions of people still live precariously, while also facing a multitude of natural threats.

The Philippines is subject to a variety of different natural hazards including volcanoes, typhoons, earthquakes, flooding, landslides.

But at the same time, it is a socially vulnerable place with many, many people living in extreme poverty.

NARRATOR: The millions of Filipino people living in coastal communities are accustomed to occasional typhoons, even super typhoons.

In the days leading up to landfall, most residents are taking the storm's approach in stride.

FATHER HECTOR: It was not an alarming thing for us.

We've been used to typhoon.

And so it was not something extraordinaryt.

Everything was just so normal.

I mean, day-to-day operation of the grocery.

People are buying, but they're not in panic.

NARRATOR: But Haiyan is already far stronger than most typhoons, thanks to near ideal atmospheric conditions.

In a strengthening typhoon, warm air rises around the eye like smoke up a chimney.

Crosswinds called wind shear can disrupt or block that flow, weakening the storm.

But in the vicinity of Haiyan, wind shear is low.

Additionally, the column of rising air benefits from winds in the upper atmosphere.

In the upper levels, you need to have outflow from the storm, and that's basically wind in a position that's going to carry the energy that comes up through the atmosphere away from the center of the storm.

NARRATOR: The high-altitude winds create a suction effect at the top of the storm, drawing even more warm air in at the bottom of the column, feeding the storm like a roaring blaze in a well-ventilated fireplace.

EVANS: I'm drawing lots of moisture, lots of air, hot energy up into the chimney.

I've got all the ingredients down at the bottom.

I'm going to grow a nice, hot, warm, crackling fire.

NARRATOR: As the storm reaches its peak intensity, the atmospheric pressure in the eye drops, possibly to one of the lowest levels ever observed, on par with the previous record, which was set 35 years earlier.

The lowest recorded atmospheric pressure ever on the planet was recorded in a super typhoon, Super Typhoon Tip from 1979.

Early on with Typhoon Haiyan, many of us suspected that it could rival Tip in terms of its strength just based on the structure and the intensity that we saw from various satellite datasets.

NARRATOR: Low pressure is an indication of how rapidly air is moving up around the eye.

Looking down at the top of the storm, satellite images also reveal that there is heavy outflow at high altitude-- not one, but two streams of warm air.

MILLS: We were able to identify what we call dual chann We were able to identify what we call dual channel outflow.

That means you have an enhanced outflow situation, which just allows that system to breathe better, vents better, allows it to grow and intensify even more.

NARRATOR: And there was yet another sign of the storm's incredible power.

In the Western Pacific we use a technique, it's called the Dvorak method, and it's where you actually look at the cloud structure, the banding of a particular typhoon, and you create a Dvorak number.

NARRATOR: Dvorak numbers indicate wind speed.

The highest number on the scale is eight, reserved for the most powerful storms on record.

MILLS: On November 7 at 7:00 a.m. our sat analyst looked back at me and she said, "Sir, we are at 8.0/8.0."

8.0/8.0 in the Dvorak scales corresponds to 170 knots.

NARRATOR: 170 knots, 195 miles an hour.

DAVID ROBINSON: This is a visible satellite image of the storm at its strongest point and you can look right down in the eye and see the ocean waters below.

The strongest winds-- this is a daytime image-- are right around the eye wall.

This storm is reaching its peak strength at this time.

This is just an incredibly powerful storm.

NARRATOR: On the afternoon of November 7, the Philippine weather service upgrades their typhoon warning to storm signal four, the highest possible.

But for those on the ground in harm's way, there is still little tangible sign of what is about to hit.

There was only a few rains, and even when we were already signal number four, very fine weather.

So... me, I was so surprised.

I was even telling myself and my kids that it's okay to have signal number four.

NARRATOR: Finally, those living along the coast begin to take note.

But preparations are far from adequate.

We started to pack our things.

We buy plastics, cellophane, big cellophane, plastic cellophanes and then we put the books, our TV, we covered it with cellophane.

NARRATOR: Haiyan is now almost 300 miles across.

Forecasters around the world are watching intently, looking hopefully for some sign that it might weaken.

EMANUEL: As Haiyan approached land and the forecasters got better data from satellites, it became very clear that this was a storm of unusual intensity.

We were looking at a potentially catastrophic storm.

NARRATOR: One reason for alarm: Haiyan is unusually consistent.

It intensified very rapidly and is now maintaining that intensity.

Typically tropical cyclones, typhoons and hurricanes will go through an ebb and flow cycle in terms of intensity.

One of the best examples that I can think of is Hurricane Katrina.

As it was making its way through the Gulf of Mexico, it blossomed into a category five storm relatively quickly, and that was because it moved over a pool of warm water called the Loop Current.

After it moved off of that Loop Current, intensity went down some.

Typhoon Haiyan maintained a relatively consistent track and a relatively consistent intensity as it was traversing the warm Pacific Ocean.

NARRATOR: With ample warm water and undisturbed by wind shear, Haiyan shows no sign of weakening.

SHEPHERD: It was a strong storm, it remained a strong storm, it made landfall as a strong storm.

Right now it's as big and mean as a cyclone can actually probably get on this planet-- winds of 195 miles per hour, gusts up to 240.

This storm peaked right as it was going ashore in the Philippines.

That's the tragedy.

MILLS: Just knowing that lives were going to be lost, infrastructure was going to be destroyed.

It's gut-wrenching.

And so I told my wife, "This is going to be ugly.

People are going to die on this one."

NARRATOR: Finally, at 4:40 a.m. local time on the morning of November 8, Typhoon Haiyan hits the east coast of the Philippines and unleashes a nightmare.

Most homes and buildings simply cannot withstand such intense, 200-mile-an-hour winds.

SUSAN TAN: Roofs flying, and some things that are flying which is unbelievable things-- motorbikes flying, even air-conditioning units.

GEORGINA BULASA: Our house was already shaking as if the wind is going to uproot the house.

NARRATOR: Residents take shelter in a local church.

I saw the windows already gone.

And wind coming inside, with the mist of water, and it's all white, it's all white.

Circling-- (imitates wind howling).

ROBINSON: The wind speeds themselves were as if you had a moderate to strong tornado coming through.

Tornadoes pass over in a minute or two.

These winds are blowing for an hour or two in some locations.

NARRATOR: The wind shreds countless homes.

CARMELITA BANTILAN (translated): The roof was blown away.

I was so scared, praying to the heavens, saying, "Please stop this rain."

At 5:00 a.m., our house was destroyed.

NARRATOR: Families find themselves exposed to the full fury of the elements, improvising ways to protect themselves.

CARLITO ARIAS: This was where we hid after our house collapsed.

We stayed right here.

I crouched over all of them.

I called their names.

I said, "Sarah, take care of Precious, our baby."

Over here was Kristel and Laiza.

There was Jamaica, Marife, Aaron, and Angel.

I huddled them together.

ROBINSON: This actually went off the scale.

It was a monster storm, a textbook example of a classically strong super typhoon.

This was a terrifying storm.

NARRATOR: The city of Tacloban on Leyte Island, home to 200,000, takes the full force of the storm.

Almost immediately, the local hospital is threatened.

The medical staff scrambles to move patients away from windows and exterior walls.

We instructed our patients to get out of their rooms and to slowly, to be on the basement where, we think at that time, was safe for us.

We place our patients here only with their IV, with their intravenous fluids.

So here they pile up here.

NARRATOR: Normally, seeking shelter on a low floor offers protection from the wind and rain.

But now there's a new and far deadlier threat-- storm surge.

Storm surge is one of the most hazardous aspects of any typhoon or hurricane.

JEFF WEBER: This storm was so intense, it had been developed for so long across the ocean, that it had an incredible amount of water behind it.

As this was coming onshore, the storm surge was as high as 20 feet.

NARRATOR: A storm surge begins when wind pushes water across the surface of the ocean.

That displacement pulls more water upward from below.

If the storm maintains its strength, the continuing churn sets up a vertical circulation, an underwater wave.

The warmer the water, the larger the storm, the faster the winds, the bigger the wave.

As it approaches land and the water becomes shallower, the wave bulges upward, causing sea level to rise.

The incredible intensity of Haiyan drives a huge storm surge which is now crashing over the coastline.

It's unlike anything the people here have experienced in the past.

With water now just seconds away from the hospital, the decision to move patients lower in the building has put them all in grave danger.

PAULO PARDILLA: The first water was up to here.

Only clear water.

Then after that we see the surge, the wind and the flood, which was up to here, that was... the color was black.

Blackish water was coming.

We try to assist our patients and to get to the second floor to get up so that we will be safe.

NARRATOR: At the local church, the wind has destroyed the roof so when the surge pours into the ground floor there's nowhere to hide.

FATHER HECTOR: And I said okay, I cannot go up and take refuge, but I cannot go down anymore because the water was rising up here, so that's the thing.

It's either the water or the wind.

It's almost like the devil and the deep blue sea.

NARRATOR: Almost every typhoon brings some flooding, but this typhoon is something else entirely.

In minutes, the storm surge ravages the coastline, sweeping away weak buildings, bringing floodwaters 20 feet deep.

One reason for the extreme height of the surge is Tacloban's location.

The city happens to sit inside a relatively shallow, protected bay.

As the surge approaches, the shallow offshore terrain pushes the water up.

And at the same time, the narrow confines of the bay squeeze the water, causing it to rise even further.

HAL NEEDHAM: In a storm surge event, strong onshore winds can really funnel water into these bays, so it's a little bit counterintuitive.

These areas that tend to be the safest for cities or marinas in a storm surge event often are the most dangerous.

NARRATOR: The height of the surge brings horrendous flooding and destruction, but there's another reason that the surge is so deadly.

The exceptional thing about this storm surge with Super Typhoon Haiyan was the speed at which it came into some of these areas like around the city of Tacloban.

Storm surges generally kind of come in in increments, a foot, a foot or two, a meter at a time.

NARRATOR: One recent example of a gradual surge-- Hurricane Sandy.

The powerful storm took 24 hours to push up to 14 feet of water onto New York and New Jersey.

But Haiyan's 20-foot storm surge arrives in just minutes.

WEBER: Video from this storm shows the 20-foot storm surge came almost instantaneously like a tsunami, and so the devastation underneath the storm is unlike anything else we have seen underneath a tropical system on this planet before.

NARRATOR: For those near the coast, there is no escape.

And for those whose houses have been destroyed, the rushing water is deadly.

CARLITO ARIAS (translated): Then the water came in.

I told them, "Get up, up, water."

And just like that, the water rose to my chest.

It was not a normal flood from rainwater but a wave coming in from the shore.

It was so sudden.

It was at my ankles, then suddenly up to my chest, and the next wave brought the water up to my neck until I was completely submerged.

My child held onto my shoulder to keep me near.

NARRATOR: It is rapidly shifting winds offshore that are causing the surge to come in with the speed of a tsunami.

As the rotating storm approaches, the first winds to strike the bay come from north of the eye, blowing north to south.

That powerful force initially shoves water away from the city.

The winds were actually blowing offshore and that was keeping the water away or even producing what we call a negative storm surge, where sometimes water is actually pushed out of the bay.

NARRATOR: Then, as the storm passes, winds coming from south of the eye, blowing in the opposite direction, come into play.

Water rushes back into the bay, pushed powerfully forward by the reversing winds.

And that's what produced the sudden, dangerous and deadly storm surge.

NARRATOR: The city of Tacloban is inundated.

At the hospital, the waters rise dangerously.

This is the level of the water.

There is a gushing of wind, there is a strong current of the water.

The other patients were terrified, were in panic and we assist the patients to be in that bed.

The bed was to slowly carry the patient up to here so that we can have them rescued here.

NARRATOR: The surge swept away everything in its path.

GEORGINA BULASA: The water came so sudden.

My children were crying.

They were all, they were in panic.

Everything floated like a paper.

The refrigerator, the divider the flat screen TV and everything.

It floated like a paper.

NARRATOR: They had steeled themselves for high winds and torrential rain.

But there was no way they could have foreseen this huge wave of fast-moving water so unlike anything anyone living here had ever experienced.

We never consider the storm surge.

And the destruction that it would bring us.

ROBINSON: It was a combination of the incredibly strong winds and the massive storm surge, and if you were in harm's way, you may have lost your life.

If you didn't lose your life, I guarantee you you were terrified.

NARRATOR: 20 hours after Haiyan makes landfall, great swaths of the 7,000-plus islands that make up the Philippine archipelago are devastated.

At least 6,000 dead, 1,800 missing, an estimated four million people homeless.

In the immediate aftermath, survivors struggle to understand why this storm brought so much suffering.

FATHER HECTOR: Why so much dead, so much casualty, with this typhoon?

The media, the local media, even our own weather center, underestimated the surge.

They were only monitoring the direction of this typhoon, the speed and the strength.

But never mentioning about the surge.

That's one of the reasons they were confident they were staying at home, because they do not know what is a storm surge.

They could have evacuated, mandatory evacuation for all the people living in the sea line.

One or two kilometers inland.

But the thing, it did not happen.

(conversing in local language) So they said that during the typhoon, they were actually here, they did not evacuate.

They were here; there were three families inside.

And when the surge came in, it destroyed the house and split them up, and in the process, they lost a lot of their family members.

NARRATOR: The Philippine weather service did predict a large storm surge, but no one expected that it would come so quickly into places like Tacloban.

Part of the challenge is in the difficulty of predicting just how intense a typhoon will be the moment when it reaches land.

NEEDHAM: That becomes a little bit difficult because you have a lot of complex things happening.

How will these different ingredients like the track of the storm, the wind speed, how will all of these things really affect the water height?

We really have a long way to go with storm surge modeling.

We've come a long way but we have a long way to go.

NARRATOR: Surge models depend not only on the coastal geography but also on wind speed and direction at landfall.

In a powerful typhoon, those variables can change rapidly, making the kind of precise prediction that might have saved Tacloban extremely difficult, if not impossible.

NEEDHAM: Tacloban, which was devastated from Typhoon Haiyan, if you shift that track a little bit, in the next storm they might not get a storm surge at all.

NARRATOR: Even without the surge, such a sustained bombardment was bound to bring death and destruction.

But there were also signs that life is very resilient.

Across the islands, many new babies weren't willing to wait for the storm to pass.

My husband shouted out, "The baby's here!

It's born!"

We were just thankful that we survived.

NARRATOR: In the immediate aftermath of Haiyan, many survivors have no water, food or shelter.

Some places are so remote that essential help is slow to arrive.

When some airports open a day later, aid begins to arrive for the victims of Typhoon Haiyan.

Cargo planes ferry high-energy biscuits, rice, water and other supplies from the U.S. That staff sergeant right there, tell him we need as many people as we can to offload that C130.

We're going to get some Marines as well.

NARRATOR: The American military deploys a strike group from Hong Kong and Japan-- nine ships, 23 helicopters and 7,000 personnel to distribute 300 tons of aid to storm-ravaged islands.

DAMON LOVELESS: So this is a helicopter landing.

It's one of the helicopters with the strike group.

And we're getting ready to load up more people and supplies.

We are bringing food, water, supplies, shelter and medicine to everyone that we can get supplies to and right off the bat, we're trying to get to the most urgent need-- typically people that are isolated on smaller islands that can only be accessed by boats or by helicopter.

NARRATOR: In the first few days, military experience proves invaluable.

It's quite busy, but it's actually something that the military is very good at and, you know, I'm just a liaison, but I can tell you, the Marine Corps logistics specialists, the Army and the U.S. Air Force, they're all magicians when it comes to that, and I'm glad that we have them on our side.

They make stuff happen and keep supplies at the front.

In this case, the front is disaster relief.

IRWIN REDLENER: In the immediate phase after a storm like this, we're trying to do two things: we're trying to rescue people who are in life-threatening situations and we're trying to provide them care to save their lives.

And then the second phase is to keep people safe and alive who survived the initial impact, because after about 72 hours, after about three days, people who survived but now need things like clean water, antibiotics, shelter and didn't get it are not surviving.

NARRATOR: The military response is critical.

Equipped to move quickly and able to reach inaccessible places, they are the first to arrive.

But after a few days, the job falls to nongovernmental agencies and other specialists, who are already laying the groundwork for a longer-term effort.

So far this has been very effective from what I have seen.

It's been one of the most effective responses I've ever seen, actually.

Had some real struggles getting aid in to start with with the logistical challenges.

The airport was destroyed, the command center was destroyed, no electricity, the roads were clogged with debris, with dead bodies, so huge logistical challenges, but now that that's up and running, now that we've got a way in, we can just see the aid effort kind of multiplying over the coming days.

NARRATOR: As the slow and difficult process of rebuilding gets underway, questions are being asked about whether this latest killer storm is linked to climate change.

Greenhouse gases like carbon dioxide generated by burning fossil fuels are building up in our atmosphere, insulating our planet, holding in more of the sun's heat and driving the temperature up.

What role do these rising temperatures play in the intensity of storms?

WEBER: Typhoon Haiyan was not caused by global warming.

Global warming or a warmer environment could have exacerbated Typhoon Haiyan.

Typhoon Haiyan was going to happen because it had the energy and it had the atmospheric conditions ready for it to develop.

REDLENER: Some scientists feel that it may not have a consequence in terms of the frequency of these storms, but it may have a big consequence in terms of the intensity of these storms.

EMANUEL: One of the great myths of climate change is that it is controversial among scientists.

It is not.

97% of all scientists who actually work on climate agree.

The only sensible approach is to regard this as a problem of risk; there will never be certainty.

If we are very, very lucky, maybe not much important will happen; if we are very, very unlucky, it will be catastrophic.

We think there is a relationship between the incidence of intense storms and climate change, but we don't actually expect to be able to see that in real data for perhaps another few decades.

The way I like to frame that is in terms of steroid use in baseball.

I can't tell you specifically which home run a Major League baseball hits was caused by steroid use.

But in the average, we know that during the steroid era there were more home runs and there were longer home runs.

And so that's kind of how I frame the discussion about climate change and hurricanes.

Any specific typhoon, like a Haiyan, can happen in a given year.

But are we loading the deck or loading the dice towards more intense storms in the future as we provide a warmer base of ocean water for these storms to tap into?

NARRATOR: Warmer oceans cause water volume to expand.

At the same time, glaciers are melting.

The result: sea level around the world is rising.

WEBER: A rising sea level makes these storms far more dangerous because it puts that many more people at risk with the storm surge.

What's not so commonly known about sea level rise is that it is not globally uniform.

The Philippines is one of the parts of the world which have seen in the last 20 or 30 years the most rapid rise in sea level, and we think in the last 30 years it was about eight inches or so higher.

ROBINSON: It's not going to take as powerful a storm surge to create the damage we saw from Haiyan if sea level is one or two feet higher 50 years from now.

So the vulnerability of our coastal communities that are traditionally or historically in the path of these storms is only going to get worse just from sea level rising, let alone the fact that we may have more of these storms or more powerful storms.

NARRATOR: Haiyan's storm surge was a function of the strength and direction of its winds, as well as the shape of the coastline and the underwater terrain...

Conditions not unique to the Philippines.

EMANUEL: We might be tempted to think in the developed world, "Well, you know, if that same storm had hit America or Britain the consequences would have been a lot less."

I don't think so.

If that storm had hit the southeastern U.S., it was so powerful that I think it would have been as much a disaster, and economically a lot more of a disaster, just because there's so much more stuff there.

NARRATOR: One densely settled area in the U.S. that might be particularly vulnerable to a lethal storm surge is on the west coast of Florida-- Tampa and St. Petersburg, home to almost three million people.

This area has all the factors that could produce a really devastating storm surge.

They have a bay there that can really funnel water into that area.

They are in the subtropics there, so they can receive strikes from hurricanes and tropical cyclones.

NARRATOR: Many hurricanes that hit Florida travel east to west across the peninsula.

But twice in 1848, hurricanes traveling northeast made landfall north of Tampa, pushing a large surge towards land.

And some storm surge modelers have said that you could get a storm surge exceeding 20 feet in the Tampa Bay area.

NARRATOR: Because no one alive has experienced that type of hurricane, few in harm's way are prepared for its effects.

NEEDHAM: If you drive around the Tampa area, if you look at the flood defenses, you will often see huge subdivisions with very expensive homes right up to the waterfront, with maybe a two- or three-foot seawall.

Easily in a major storm surge those homes would just be completely washed away.

You need a very specific track to funnel water into that bay.

It doesn't happen too frequently, but it has happened before and it will probably happen again.

NARRATOR: And that's just one community that may be vulnerable.

In an era of rising sea levels, hundreds of millions of people around the world may be affected by coastal flooding.

As the aftermath in the Philippines makes plain, the stakes for any vulnerable coastal community threatened with a category five hurricane or super typhoon are high.

Haiyan has created one of the worst resettlement crises in recent memory.

An estimated four million people have been displaced, more than twice the number made homeless by the deadly tsunami that struck Indonesia in 2004.

In the hardest hit towns, the relief effort will need to continue for years.

Even those who have witnessed other catastrophes have difficulty coming to terms with the extent of the loss.

CAT CARTER: I came down walking just a few days after I arrived and I looked out over the ocean and I remember seeing a boat out on the sea and thinking that, you know, oh, that's great they're fishing again.

It's a sign of resilience, look how quickly they've got past the disaster, and it took a little while, I think, for my brain to catch up with what my eyes were seeing, and then I realized that they weren't fishing, they were pulling dead bodies from the water.

And all along the beach they'd lined up dead bodies and lots of them were children.

And that was kind of the moment for me that the enormity of what had happened here kind of came crashing down around me.

NARRATOR: In the town, sick and injured people flooded into Bethany Hospital.

Nurse Paulo Pardilla worked tirelessly to save lives, but he had no idea if his own family was dead or alive.

I had no communication with them because the cellular phones, the link of communication, was shut down, but I was just praying that my family was safe.

NARRATOR: Paulo spent 24 hours helping in the hospital.

Then he walked to his home in a village on the outskirts of the city.

There was no transport.

Everything was in ruins.

He had no idea what he would find.

It took him a day.

But to his relief, his mother and family were all alive.

GILMA PARDILLA: This is the first time in my life, this is the strongest storm I ever experienced.

NARRATOR: Paulo's brother's family, next door, also survived.

But their house did not.

PAULO PARDILLA: It was that fruit tree.

A big branch of that was able to fall on the house of my brother.

PATRICK PARDILLA: My daughter was so scared, so we ran out and go to our mother's house.

NARRATOR: The concrete walls of Paulo's mother's house withstood the fierce winds of Haiyan, but they were no protection against the storm surge.

Flood waters rushed through the house, and for eight hours the family huddled together on the steps.

We sit down here, my granddaughter, my daughter-in-law here, my husband standing, holding the ceiling because it might fall to us.

We just keep on praying, "Lord, please save us."

NARRATOR: Paulo's family was spared.

But their city had become a disaster zone.

Whole neighborhoods were left barely recognizable.

You could not see many of the houses there because it's covered with foliage like trees and leaves, but now you can see even the mountain at the end.

Now it's all gone.

REDLENER: In many developing countries, there is no choice.

If you want to support your family and yourself, you have to live near the coast.

You are forced to remain in place even in these high hazard zones.

NARRATOR: Many survivors are haunted by memories of what they endured during the storm.

With his home blown away, Carlito Arias found himself desperately holding on to his children as the sea surge came rushing in.

(translated): My child held on to me, but the next wave took me far away from them.

That was the most painful part.

I couldn't protect them any longer.

NARRATOR: Once the storm had passed, Carlito searched for the children and relatives he had tried to protect.

One by one, he found their bodies.

He was then left with the task of burying his dead.

ARIAS: I told the family the news, that we didn't have a choice but to bury them ourselves.

So we wrapped them well in hand-woven mats.

NARRATOR: The burial was swift.

No time for the usual embalming and coffins.

They were laid to rest, all together, in a sacred place.

I want to cement it well.

To show I haven't forgotten and still love them.

EMANUEL: I don't think anybody could have dealt with this typhoon because it was so out of the normal range of intensities.

Haiyan became as destructive as it did because of a coincidence of very favorable circumstances.

Haiyan had everything going for it.

In some sense the people of the Philippines had everything going against them in this event.

NARRATOR: Among the millions of people left without a roof over their heads are Georgina Bulasa and her husband.

BULASA: That is my husband.

Building a house, a very simple one.

He is just using whatever is usable now.

Besides, we do not have the money to buy materials and there is no store that is open, so me and my husband are hoping that in due time we will be able to start anew again.

NARRATOR: Nurse Paulo Pardilla is back to helping those affected by the typhoon.

With Tacloban's hospital flooded, relief workers have set up a temporary medical center.

PARDILLA: What's new in the last two days for us is that there's a feeling of joy, of hope in our life, especially for us nurses, because we can continue our work.

Today our hospital is not yet opening or not yet in service so the tent hospital is a means for us to continue rendering care and service to the people, especially those affected by the typhoon.

(giving instructions to patient) NARRATOR: The Philippine government estimates the cost of reconstruction at around $8 billion.

In the affected area, key industries such as agriculture and fishing have all but been destroyed.

For the people on the ground, it would be easy to be overwhelmed, but the job now is to rebuild.

We don't have no plan to go elsewhere, but to stay here and rebuild whatever we can because this is our home.

No place like sweet home.

NARRATOR: The priority for Father Hector is his parish.

This is a religious community, and for many the church is needed more than ever.

FATHER HECTOR: We always have that strong spirit to rebuild in our own little way, in our own simple way.

We don't have a roof over our heads.

But the thing is, they will do their best to celebrate that mass and I believe they would be coming in to be grateful to God for their lives.

CARMELITA BANTILAN: What are we going to do?

Even money to buy little things, we don't have any.

So what are we going to do?

GEORGINA BULASA: We're hoping that big hope that slowly we're going to make it back to normal again.

(bell ringing) FATHER HECTOR: It's a tradition for Filipinos that they never give up, in spite of all these disasters in spite of all the tragedies.

They won't give up.

We lost a lot of lives, and that's a fact that we have to accept and to live with.

It will take some times.

It's part of our culture that in spite of all the pain, the suffering that we have endured, we are still smiling.

On NOVA, victims of a gruesome slaughter.

This NOVA program is available on DVD.

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Captioned by Media Access Group at WGBH access.wgbh.org