NOVA examines the effects of past and present El Niños on global weather and follows the work of scientists who are trying to understand and predict this phenomenon.
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00:00During the following program, look for NOVA's webmarkers, which lead you to more information at our website.
00:07Tonight on NOVA, it strikes with fury with the energy of half a million hydrogen bombs, creating chaos across the globe.
00:20None of the forecast models predicted how huge it would be.
00:24Now, scientists confront the weather monster, head on.
00:29Can they predict the next onslaught? How hard will it hit?
00:34Chasing El Nino.
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01:37And by the Corporation for Public Broadcasting and viewers like you.
01:42We live in an ocean of air.
01:57Seething around us.
01:59Always changing.
02:01Always on its way to somewhere else.
02:04Sometimes with great fury.
02:07In the skies and the seas below them, an ancient and powerful engine generates Earth's weather.
02:20Fueled by the fires of the sun, it is a machine that converts heat into motion, relentlessly churning the atmosphere into a chaos of wind, rain, and storms.
02:36In the trillion and a half days since the Earth was born, not a minute has passed in which a storm did not raid somewhere on the planet.
02:49But once or twice in a decade, a shift occurs, and hidden energies surge through the system.
03:01A mysterious phenomenon called El Niño raises the weather machine to a fevered pitch, causing devastating floods along the coasts of North and South America.
03:20Then El Niño's influence reaches beyond the Pacific coasts, turning lush fields into drought-ridden wastelands, chilling winter rains into lethal ice, transforming dense forests into raging infernos.
03:47Only the seasons have a greater influence on global climate than El Niño.
03:54Despite its enormous impact, in many ways it remains a mystery.
04:02What causes it?
04:03What determines how strong it will be?
04:09A handful of scientists have embarked on a quest to uncover its secrets.
04:17Mike McFadden, an oceanographer, has spent 20 years chasing El Niño.
04:23El Niño is a fascinating scientific problem, and it's challenging in the sense that it requires a variety of skills and expertise to address the issue in a serious and significant way.
04:40And so, because of those challenges, it's not routine science.
04:47And furthermore, it's science in service to mankind, you might say, that the impacts of El Niño are felt worldwide.
04:55And so, it's more than just an academic exercise to try and understand it, but it has real value to people all over the planet.
05:05McFadden's team patrols the Pacific Ocean, trying to learn how forces within these deceptively tranquil waters alter weather around the world.
05:20The Pacific, the single largest feature on the face of the Earth, controls most of the planet's climate during normal periods, and El Niño's.
05:36To understand what El Niño is, you have to understand what normal is.
05:39And normal is, the trade winds blow from east to west, and they pile up warm surface water that's been heated by the sun in the tropics in the western Pacific.
05:50And this creates a very deep, warm pool of water.
05:54And the system is actually quite stable in a normal condition.
05:59But every three to seven years, something makes the trade winds slacken or even reverse direction.
06:08Then, the warm water that the winds normally push towards Australia and Indonesia, sloshes back across the Pacific, toward the South American coast.
06:24The enormous pool of unusually warm water changes wind patterns, disrupting normal weather everywhere.
06:37Wet places become dry.
06:41Dry places become wet.
06:44El Niño's symptoms are evident, but not its causes.
06:50I think one of the outstanding questions, or mystery if you will, about El Niño is what triggers it.
07:01We don't have a theory yet that can explain the onset of all the events that we've been able to observe.
07:10In order to understand El Niño, and to be able to predict more precisely when it will occur, Mike McFadden and a group of scientists from the National Oceanic and Atmospheric Administration needed more information from the Pacific.
07:35Their work began in 1984 at NOAA's Pacific Marine Environmental Laboratory in Seattle.
07:44Their plan was to track El Niño by building a network of electronic sensors attached to buoys.
08:00These buoys measure all the critical environmental parameters you need to know for understanding El Niño.
08:09They measure the surface winds, the surface temperatures, the upper ocean temperatures, and at some locations they measure ocean currents.
08:17It took 10 years to move 70 buoys from concept to lab to ocean.
08:27But by 1994, the first El Niño early warning system was in place.
08:36Stretching across 8,000 miles of the Pacific Basin, it was one of the largest scientific instruments ever built.
08:51I would describe our buoy system as not necessarily high-tech.
08:55I would describe it more as ingenious.
08:58We make use of technology where it suits our purposes.
09:01We do use state-of-the-art electronics, state-of-the-art environmental sensors, state-of-the-art satellite communications.
09:09But we've designed the system to be very low power, so we can run them on flashlight batteries.
09:16The buoy array is maintained by a NOAA ship called the Kaimi Moana, Hawaiian for the ocean seeker.
09:26The crew of scientists and sailors spends 260 days a year tending the system.
09:41Each buoy has a satellite transmitter, so we know where it is at any given time.
09:46In the particular case of a buoy at 2 South 95 West, we saw it move 20 miles from its deployment location over a period of several days.
09:57And then it suddenly stopped transmitting.
10:00So, on our regularly scheduled cruise down this line of buoys, we diverted to the location of the last satellite transmission,
10:13and then began to scout the area for what we hoped to be the finding of this errant buoy.
10:19Mike McFadden joins Captain Mark Cain and Chief Scientist Mark of Lundy in the search to find the lost buoy that cost $50,000 to build,
10:33but is priceless in terms of the data it gathers.
10:38The buoy is missing from the eastern edge of the array, where El Niño's warmest waters approach the South American coast.
10:49Its absence leaves a critical void.
10:53This one hasn't been transmitting since December 13th, so it may not be there.
10:59We'll go over there and look, and we can put the transponder hydrophone down and at least be able to find that.
11:07Alright, let's do it.
11:09Okay.
11:10Yeah, that's right.
11:11We got a big, pretty good sized wall up ahead of us here.
11:13Right.
11:14We probably will not get a visual on it until we're right on top of it.
11:18The watch circle for this thing can be a couple of miles, too.
11:21So, that's going to make it problematic.
11:24You'll know it when you see it.
11:27It's going to be the only unnatural thing on the horizon.
11:30The rain makes the search more difficult.
11:35And they're not sure what they'll find.
11:40The anchor line may have been cut.
11:42Or the buoy may still be in position and not transmitting.
11:46But if strong currents have dragged the anchor into deeper water,
11:50the buoy may simply have been pulled below the surface.
11:55Nothing yet.
11:57Right now we're in a, the buoy's in a, if it's there, it's in a squall.
12:01We can't see anything.
12:04They search the vast waters of the Eastern Pacific for hours.
12:11Their only clue, the location of the last satellite transmission,
12:16before the buoy stops sending data.
12:19When they reach that position, they send a signal to a device called an acoustic release,
12:26attached to the anchor of the buoy.
12:29But the signal can only be received if they come within five miles of the missing anchor.
12:40For several hours there is no response.
12:43Perhaps the buoy has drifted.
12:46Finally they have some luck.
12:53Yeah, we got it.
12:55The ship's repeated queries are received by the acoustic release,
12:58which beams a reply signal back to the ship.
13:01The crew hones in on the location of the anchor and then sends another signal,
13:10ordering the acoustic release to uncouple the mooring line.
13:16If the buoy is submerged but still attached to the line, it should pop out of the water.
13:28We triggered the release hoping that it would pop up on the horizon and there would be a great hurrah that we had found it.
13:45Nothing huh guys?
13:55Zero.
14:07Despite their best efforts, the buoy is gone.
14:13The loss of a buoy is a cost of doing business in the Pacific,
14:17where powerful ocean currents can sometimes dislodge even 4,000 pounds of anchor.
14:23But in this case, the ocean might not have been the culprit.
14:30Buoys attract fish, so fishermen have been known to borrow these rather high-priced lures.
14:40In not all cases do fishermen understand how fragile the instrumentation is
14:46or how important the data are actually for their own activities.
14:50And in fact, on some of the buoys we serviced on this particular cruise,
14:54we found fishing gear and other evidence that these buoys had been visited by fishermen.
14:59Peruvian fishermen have always been the first to know when an El Niño was underway and the first to suffer its consequences.
15:18The El Niño current makes the water hot and the fish don't like that.
15:25They move out where the ocean is cooler, which is too far for us to follow in our boats.
15:30In most years, Peru is the number one fish exporter in the world, mainly of anchovies and sardines processed into fish meal.
15:47But during a major El Niño in the early 1980s, the industry collapsed.
16:02The 1982-83 El Niño wreaked havoc throughout Peru, where areas in the north received 30 times the normal rainfall.
16:15With no advance warning and no emergency preparations, Peruvians suffered a billion dollars in damages.
16:28Reaching well beyond Peru's borders, El Niño's worldwide toll would rise to 13 billion dollars in property and crop losses.
16:432,000 people would die.
16:49For the first time, El Niño would be recognized as a force of global influence.
16:58As a scientist who's based his career on the study of El Niño, you sometimes lose touch with the human dimension.
17:07And to see the flooding and the inundation was a very moving experience because it reminds you and humbles you that this phenomenon affects the lives of so many people.
17:21And it makes you understand and appreciate the importance of what it is you do and the hope that that information that you generate can be used in ways that can mitigate against some of this human suffering.
17:35Before the devastation began in 1982, the El Niño had grown steadily for months.
17:48But with no buoy array at the time, the scientific community was caught off guard.
17:53Climate scientist Tim Barnett of Scripps Institution of Oceanography was one of dozens of experts in the early 1980s who was watching for El Niño.
18:06In September of 82, there was a conference on El Niño and everybody was there.
18:12And I think it was the consensus of that conference, or at least most of the people, there would be no El Niño that year.
18:17And of course, we were two months away from the height of what at that time was the biggest El Niño of the century.
18:21Unfortunately for the climatologists, they'd been misled by a volcano.
18:28In Mexico, El Chichenal had recently and violently erupted.
18:36Highly reflective mist from the volcano had obscured the vision of satellites circling above.
18:46Falsely lowering readings of sea surface temperatures by several degrees.
18:53Masking the growing El Niño.
18:56On the eve of the next major El Niño, forecasters would have a new weapon in their diagnostic arsenal.
19:04They'd have the buoy array.
19:07The buoys would provide the first accurate portrait of the entire Pacific basin.
19:15Precise enough to calibrate satellites that were once deceived by a volcano.
19:22I think the strength of the El Niño observing system is that we have both a combination of satellite measurements and in the ocean measurements.
19:34The satellites give you a global picture. Unfortunately, they see only the surface.
19:40If you want to understand what's going on below the surface, you have to put instrumentation into the ocean.
19:47Deploying a buoy is perhaps the most challenging operation on board the Kain Moana.
19:58If all goes right, it should take about four hours.
20:13We start by rigging the buoy, putting the instrumentation on, putting the lines on.
20:18Antenna.
20:23After that's done, it's hoisted over the side with a crane.
20:28All the crew is out and they've got their ropes on it.
20:32And you see men and machines working against or with the sea, as it may be.
20:37Up a little bit.
20:39That's good.
20:43Once the buoy is in the water, the crew reels out nearly three miles of mooring line, which carries sensors to measure water temperatures and currents at various depths.
21:08Without the buoys, these scientists would be as blind to a growing El Nino as they were in 1982.
21:23With them, McFadden and his team know, as it's happening, when an El Nino is brewing.
21:29Whoa, that is warm.
21:3429.8.
21:37That's why we can't run the engines at full speed.
21:40We can't cool them in the water this warm.
21:44Water temperature of nearly 86 degrees Fahrenheit, roughly 15 degrees above normal in this part of the Pacific, is a definite symptom of El Nino.
21:56One of several indicators the buoy array measures to detect an impending event.
22:06In December of 1996, the first hints of a change began blowing in the Pacific.
22:13Suspicious wind pulses started.
22:16Fluctuations that can sometimes mark the onset of an El Nino, but not always.
22:23Then, over the next few months, the buoys detected signs of something more ominous.
22:30The trade winds slackened, and ultimately changed direction, almost certainly heralding a new El Nino.
22:40This time, people were watching.
22:47The information from this buoy array is used widely all over the world.
22:52Centers for weather forecasting and climate forecasting make use of this data.
22:57It's ingested into their computer models.
23:00For our model, we know the basic physics that govern the ocean changes in temperature and currents and so on.
23:09And we can write those down as a set of mathematical equations.
23:12Now, once you have this large set of mathematical equations, they're too complex to sit down and just write the answer out on a piece of paper.
23:18So that's when you turn to the computer and program the computer to solve those for you.
23:22And the net result of that's called a model.
23:24And the net result of that, then, is an El Nino forecast.
23:27Processing information collected by buoys and satellites,
23:33TIM and other climate modelers were able to do what they couldn't just 15 years earlier.
23:39See an El Nino coming.
23:48Within weeks of their forecast, warm water began racing toward South America at a rate of up to 150 miles a day.
23:59Sea surface temperatures in parts of the eastern Pacific rose 5, 10, over 15 degrees Fahrenheit.
24:08The heated water contained a staggering amount of energy, equivalent to exploding half a million 20 megaton hydrogen bombs.
24:20This is the energy that would fuel the disruption of the world's weather.
24:27While most major computer models did predict the 1997-98 event, they forecast an El Nino only of minor to moderate intensity.
24:37None of the forecast models predicted how huge it would be, and none of them predicted how rapidly it was going to develop.
24:46And so there was a surprise here, different than the surprise in 1982-83, where we didn't even see it coming at all.
24:53There were several of us that forecast this event a year in advance.
24:56Well, at those long-range forecasts, we missed the magnitude by almost a factor of three.
25:02Almost a factor of three.
25:03We would have said, yes, in January of last year there's going to be a mild or moderate El Nino.
25:07Well, it was a whopper.
25:08We've studied El Nino long enough now to realize that when it occurs, there are identifiable impacts all over the world.
25:27The heavy rains and flooding in North and South America, droughts in South Africa, droughts over the Indian subcontinent.
25:45We can interpret disparate events happening around the world that you would normally think are completely unrelated.
25:54So why should these be related? Because they all have a common origin, the tropical Pacific.
26:00The normal equilibrium of the ocean is upset by the abnormally warm waters of El Nino.
26:12At high temperatures, you have much greater evaporation of moisture.
26:16And this moisture-laden air, when it rises, condenses and precipitates out in the form of rainfall.
26:25During El Nino years, the heavy precipitation that is normally found over the western part of the Pacific, Australia, Indonesia and the Philippines,
26:35migrates eastward with the warm water.
26:38And so what that does almost immediately is it leaves Australia, Indonesia and that part of the world high and dry.
26:44Drought, potentially famine, and all the ramifications that go with that.
26:55In Indonesia, farmers light fires every year to clear forests for planting.
27:02Normally, they can rely upon the rains of monsoon season to douse the flames.
27:08But during the El Nino-induced drought, fires raged out of control, filling the air with choking smoke, pushing pollution levels to record highs,
27:20and sending tens of thousands of people to seek medical aid for respiratory ailments.
27:29All because the rain moved eastward.
27:33When you change this precipitation pattern, you're also changing the heating for the general circulation of the atmosphere.
27:42And so this has impacts not just in the Pacific Basin, but all around the world.
27:47The entire tropical circulation around the entire planet is linked together.
27:52And so when you have an El Nino, let's say in the Pacific, it affects that entire circulation,
27:57which affects the winds and the rains and so on over the Indian Ocean and somewhat over the Atlantic.
28:01I think we were all sort of stunned to see that this patch of water in the Pacific Ocean could have impacts on such far-reaching areas of the globe,
28:11as has now been shown quite clearly.
28:14When El Nino's pool of exceptionally warm water evaporates off the ocean's surface, it doesn't just form clouds.
28:23It also creates a huge column of warm, moist air that bulges upward six to ten miles into the sky.
28:34Like a boulder in a river, this mass of air forces winds to flow around it,
28:40displacing the jet streams and the weather patterns they deliver to the rest of the world.
28:46The El Nino is not a storm. There are not El Nino storms. There are storms all the time, whether there's an El Nino or not.
28:55I think people think of it like that. But what it really is is a fairly momentary change in the climate of planet Earth.
29:03That's what it is. And so as that climate changes, all the details of the climate, the weather, change too, which is what we see.
29:11The climate changes reach all the way to Africa, where some countries flood, while others endure droughts.
29:26The same area can be wet in one event and dry in the next, depending on the fickle twists and turns of air currents disturbed by El Nino.
29:40Dislocated jet streams deliver fierce storms to California that would ordinarily land far to the north in Alaska or Canada.
30:02California's magnificent coastlines normally erode four inches a year.
30:15But during the first few months of the 1998 El Nino, some cliffs retreated ten feet.
30:22Despite early warnings, scores of homes could not be saved.
30:29The winter storms this year have been really remarkable.
30:34And I think a number of us scratching our head.
30:36Because you can look at a satellite picture and you see them lined up, particularly in February,
30:40three or four of them all coming zipped right across the ocean.
30:43And the path they took was just, you know, bam, bam, right into central California time after time.
30:48Meteorologists working in California had to improve their ability to forecast which El Nino powered storms would strike the coastline and which ones would wait to hit the more desolate inland mountains.
31:07There was an urgent need to know how this global climate event would affect local conditions.
31:22A research team led by Marty Rauf planned a daring series of flights that would measure storms by flying directly through them,
31:31gathering information that is otherwise impossible to get.
31:35The basic problem is this region out in the Pacific has very limited data.
31:44There might be 40 measurements from, you know, a handful of ships going through maybe some commercial aircraft that are flying up at high levels.
31:53Over a comparable size area in the US, there are probably 20,000 measurements.
31:58So we call this the Pacific data void.
32:02And one of our objectives is to get detailed measurements out here.
32:07With weather radars and wing-mounted sensors, Marty and his team measure wind speed, temperature, rainfall distribution,
32:16and atmospheric pressure from within the storm as it heads directly for California's Monterey Coast.
32:28In order to create a three-dimensional portrait of the storm, readings must be taken at a range of altitudes,
32:35beginning at just 200 feet above the ocean.
32:39As the plane crosses the storm front, passing from relatively stable cold air to El Nino-energized warm air, the ride gets rougher.
33:00As we call it the climb from Dr.
33:20Our position here is about 50 kilometers ahead of the front.
33:25The winds right now at our location are at 50 knots.
33:28We could end up with hurricane-course winds up here along the coast.
33:31Yeah, yeah.
33:35Arnino pumped this storm full of tropical heat and moisture,
33:39two primary ingredients for enormous precipitation.
33:45But Marty's team still couldn't be sure where this storm would hit,
33:50inland or at the coast.
33:52Then, a few miles offshore, they observed something unexpected.
34:02They found a wall of air called a blocking front
34:05that was forcing the precipitation out of the clouds near the coastline.
34:11We saw something that makes the rain form offshore first before it hits the coast,
34:17and that was a blocking front.
34:19This may be useful to help forecasters better predict whether to expect the heavy rains
34:26right at the coast, where the highways are, where the people live,
34:29or inland in the mountains where they usually get them.
34:33It's moistening up in that barrier flow.
34:35Yep.
34:36So where that thing goes up the slope sometime later today, further north,
34:41that's going to help create a lot more rain.
34:43I was surprised.
34:44I thought this area here was going to be the moist one,
34:46but no, the area there was the moist one.
34:48We just discovered something.
34:53All right.
34:55Nobody can argue with what we found today.
34:58So I feel like in my career, there's been a handful of times
35:01when I sit back and say,
35:03you know, I found something new today, really new.
35:07And this is one of those days.
35:12The discovery of blocking fronts helps explain
35:15why parts of California's coastline endured some of El Nino's fury.
35:22Still, other places in the United States
35:25actually benefited from the climate change.
35:27There are winners and losers with El Nino.
35:33It's clear that people suffer when there are heavy rains and flooding
35:36or droughts and wildfires.
35:40But it's not a complete negative phenomenon from that point of view
35:45because it tends to reduce the number of Atlantic hurricanes, for example,
35:49and that has a very positive benefit to people
35:52who live on the east coast of the United States.
35:54The 1997 hurricane season was one of the quietest on record
36:02with only three hurricanes,
36:05half the number that typically strike.
36:11Winds high over the Atlantic stimulated by El Nino
36:14blew developing hurricanes apart
36:17before they had a chance to organize and grow.
36:24In the Midwest and northern United States,
36:27places that normally bear the brutality of winter weather
36:30found relief in El Nino.
36:34The winters in the Pacific Northwest
36:35in the northern tier of the United States
36:37tend to be warmer, and that reduces heating costs.
36:40It's a two-sided coin.
36:42On average, I would say
36:43it's more negative than positive, though,
36:46for human activities.
36:48El Nino always strikes Peru first
36:59and hardest.
37:03There is no place for me to go.
37:06With the first rains, my house was destroyed
37:08and I moved away.
37:09Now, these rains have destroyed my house again.
37:12The 1997-98 El Nino
37:17left a quarter of a million people homeless,
37:22nearly 300 dead,
37:25and an unknown number of casualties
37:28from malaria and cholera,
37:30diseases that inescapably arise
37:32from stagnant floodwaters.
37:34But the advance warning of El Nino
37:42did help some Peruvians prepare for the onslaught.
37:50Based on an estimate
37:51that every dollar spent on prevention
37:53would save $10 in disaster relief,
37:57the government began widening
37:58some waterways in northern Peru
38:00that were sure to overflow.
38:02In 1983, it was six months
38:08or eight months
38:09not only of water
38:10but of mud.
38:12Now, the flood may stay
38:16six hours, ten hours,
38:19but after that,
38:21the city, again, is clean.
38:23That's a big difference.
38:29Still, the advanced warning
38:31could not bring fish back
38:32to Peruvian waters.
38:38Independent pescadores,
38:40still using bead boats
38:41their ancestors have made
38:43for generations,
38:44cannot earn a living
38:45during El Nino.
38:46In most years,
38:53I can catch 80 kilos.
38:55This year,
38:55I have only gotten 20 kilos.
39:01This year is much worse
39:03than 1982.
39:04This is the worst
39:06El Nino I have ever seen.
39:07Fishermen with no catch
39:24participate in ancient rituals
39:26meant to bring fish
39:28back to their empty nets.
39:29Peruvian shamans
39:34Peruvian shamans
39:36have been helping
39:36their faithful contend
39:38with El Nino
39:38for centuries.
39:40But no one knows
39:42just how long
39:43and how often
39:44El Nino has been
39:46influencing
39:46the earth's weather.
39:47Archaeologists working
39:55at one of the largest
39:56pre-Columbian temples
39:57in South America
39:58are uncovering
40:00new evidence
40:00of El Nino's destruction
40:02dating back
40:03to the 6th century.
40:07Near Truillo,
40:08in northern Peru,
40:10sits the ancient
40:11moche Huaca de la Luna,
40:14the Pyramid of the Moon.
40:15Archaeologically,
40:21here at the Huaca de la Luna,
40:23we have found
40:24three events
40:25of the El Nino phenomenon
40:26that come between
40:27550 and 650 AD.
40:33The collapse
40:34of the moche culture
40:37probably happened
40:38in a very large period
40:39between 600 and 800 AD,
40:42after the El Nino storms.
40:45The moche predated
40:47the Inca.
40:48And their capital,
40:50while quite sophisticated,
40:51was built of mud bricks,
40:53highly vulnerable
40:54to any flooding.
40:58There were canals
40:59that supplied water
41:00throughout the city.
41:03When the El Nino happened,
41:06these canals flooded
41:07and inundated the city
41:09and destroyed the basis
41:11of the foundations
41:12of the buildings.
41:14The houses
41:16began to collapse.
41:17As this flood
41:28overran the moche city,
41:30torrential waters
41:31deposited smooth stones
41:33that could only be found
41:34in the riverbed
41:35nearly two miles away.
41:40Testimony to the force
41:41of the deluge
41:42that overwhelmed
41:43these people.
41:44more digging
41:50behind the pyramid
41:51of the moon
41:51led to another
41:52disturbing discovery.
41:57Ninety skeletons
41:59buried under
41:5915 layers of mud.
42:01They had all been sacrificed
42:06in three distinct ways.
42:08One,
42:08with a blow to the head.
42:10Two,
42:11slashing the throat.
42:12And three,
42:13with spears.
42:16In their desperation
42:18to stop the floodwaters
42:19of 560 A.D.,
42:21the moche
42:22sacrificed men,
42:24women,
42:25and children
42:25to their gods.
42:27We have evidence
42:32that these sacrifices
42:33were generated
42:34when the Aniño rains
42:36poured down.
42:38The first is that
42:42these enclosures
42:43were closed
42:44and the mud
42:45could only be caused
42:46by very strong rains
42:47that melted
42:48the adobe walls.
42:50And secondly,
42:56the bodies
42:56are imprisoned
42:57in mud,
42:58which means
42:58the mud
42:59was still fresh
43:00when they made
43:00the first sacrifices.
43:05The sacrifice
43:07of 90 people
43:08represents
43:09a symbolic act
43:10of the moches
43:11to atone themselves
43:13with their gods.
43:18It is a chilling reminder
43:19of El Niño's power
43:21over the course
43:22of civilization.
43:24But each El Niño
43:25also leaves
43:26an imprint
43:27on nature.
43:35Tree rings record
43:36the age of a tree,
43:38but the familiar bands
43:39also bear the marks
43:41of past El Niños.
43:45I'm a dendrochronologist,
43:47which means
43:47I study the growth
43:49of trees
43:49as an indicator
43:50of past climate
43:52and past events.
43:55Trees have a story
43:56to tell us
43:57and my job
43:59is to interpret
44:01what they are telling us.
44:05To obtain a sample
44:07from a tree,
44:08we extract this core,
44:10which is only
44:10about five millimeters
44:11in diameter
44:12so that we don't
44:14cause any damage
44:14to the tree.
44:15The chronology
44:19will have
44:20years that show
44:21little growth
44:22and years that show
44:23higher growth.
44:25The larger growth years
44:26are the years
44:28when there was
44:28higher winter
44:29and spring precipitation.
44:31That is
44:32the El Niño signal
44:33that we see
44:34in the tree rings.
44:38Franco Biondi
44:39generally samples
44:40trees in regions
44:41where it normally
44:42does not rain.
44:44So when he sees
44:45large annual growth bands,
44:47he knows they must be
44:48the result of precipitation
44:49from El Niño.
44:54To identify
44:54specific years,
44:56he must cross-match
44:57samples
44:58in the laboratory.
44:59The visual matching
45:02of the ears
45:03is done
45:04underneath the microscope.
45:07We can see
45:07the history
45:08of El Niño's
45:09from tree rings
45:10as far back
45:11as the age
45:12of the trees.
45:17In the rings
45:18of the oldest trees
45:19he has sampled,
45:20Franco has been able
45:21to detect evidence
45:22of El Niño's
45:23dating back
45:24more than 300 years.
45:26All right.
45:28First,
45:28the rings
45:29are going to show up
45:29pretty well.
45:30Other tree studies
45:31reflect an increase
45:32in the number
45:32of El Niño events
45:33beginning in 1870.
45:37But dendrochronologists
45:38will have to compare
45:39the results
45:40with other historical records
45:41before they can be sure
45:43that the frequency
45:44of El Niño
45:44is really on the rise.
45:46The dramatic history
46:05of El Niño's impact
46:06on nature
46:07can best be seen
46:08on the Galapagos Islands.
46:10Lying on the equator
46:16600 miles
46:18off the coast
46:19of South America
46:19these remote islands
46:22are steeped
46:23in some of El Niño's
46:24warmest waters.
46:25Here, the ocean
46:34determines who wins
46:35and who loses
46:36during an El Niño.
46:37But no animal
46:43is left untouched.
46:47In the overheated seas
46:49of the 1982-83 El Niño
46:51fish-loving Galapagos
46:53penguins starved
46:55losing nearly 80%
46:57of their population.
46:58But tortoises and finches
47:03land-based creatures
47:04flourished on the
47:06suddenly verdant islands.
47:12The mystery of the Galapagos
47:14is how the species
47:16on these islands
47:17have adapted
47:17over the millennia
47:18to the occurrence
47:19of El Niño
47:20and how that's changed
47:22the course of evolution.
47:23We haven't thought of it
47:24in these terms before
47:25that El Niño
47:26is a very strong force
47:28in evolution
47:28of the species
47:29at least in this region.
47:35Perhaps the strongest
47:36evidence of El Niño's
47:38evolutionary influence
47:39was seen in 1982
47:41when El Niño
47:42returned to the Galapagos.
47:44It poured rain
47:58for eight months
47:59over these island deserts
48:01triggering an extraordinary
48:02response in some
48:04of the animals.
48:07The medium ground finch
48:09fish, one of the 14 species
48:11of birds known as
48:12Darwin's finches
48:14always exists
48:15with a range
48:16of beak sizes.
48:19But in the drought
48:20that preceded El Niño
48:21large beaks dominated.
48:25Then, within just a few months
48:27of the onset
48:28of the El Niño rains
48:29conditions began
48:31to strongly favor birds
48:32with smaller beaks.
48:33The little beaks
48:37were far better suited
48:38to feed on the small
48:39softer grass seeds
48:40prevalent in the moist climate
48:42than the bigger
48:43harder cactus seeds
48:45that normally dominate
48:46these islands.
48:49During the El Niño
48:51the finches began reproducing
48:53at a feverish pace.
48:55Some birds bred
48:56not once
48:57as might be expected
48:58but eight times.
48:59even juveniles
49:02as young
49:02as three months old
49:03started breeding.
49:06The change
49:07in the climate
49:08had turned
49:08the finches
49:09into mating machines.
49:13By the time
49:14the rain stopped
49:15the population
49:16of all finches
49:17had skyrocketed.
49:19But continuing
49:20abundance
49:20of small seeds
49:22greatly favored
49:23birds with small beaks.
49:26On one island
49:27the population
49:28of medium ground
49:29finches
49:30once dominated
49:31by big beaks
49:32had shifted dramatically.
49:34This group
49:35was now
49:35mostly smaller beaked.
49:39These finches
49:40were changing
49:41their form
49:41in response
49:42to El Niño.
49:46Evolution
49:46is normally
49:47thought to operate
49:48on timescales
49:49of thousands
49:49of years.
49:51But here
49:52was clear evidence
49:53of natural selection
49:54producing striking
49:55changes
49:56in mere months.
49:59the remarkable ability
50:03of a species
50:04to respond
50:04to the climate
50:05takes a long time
50:06to incorporate
50:07into a population
50:08of animals.
50:10And it suggests
50:11that El Niño
50:12has been visiting
50:13these islands
50:14for a very long time.
50:15I think it's fair to say
50:21that as long as
50:23there has been
50:24a Pacific Basin
50:25whose boundaries
50:26are approximately
50:27those of today
50:28that El Niño's
50:29have been occurring.
50:31Now,
50:31the present boundaries
50:32of the Pacific Basin
50:33were established
50:34about three to five
50:36million years ago
50:37with the closure
50:38of the Isthmus of Panama,
50:40that strip of land
50:41that connects
50:41North and South America.
50:42and so
50:44one could surmise
50:45that El Niño's
50:46have been occurring
50:47for at least
50:48three to five million years
50:49and possibly longer.
50:56If El Niño
50:57has been a natural part
50:58of the Earth's climate cycle
50:59for so long,
51:01predating human presence,
51:03it's clear that people
51:04haven't caused
51:05the phenomenon.
51:08But have we changed it?
51:10Until very recently,
51:21an El Niño
51:22of the magnitude
51:23of the one in 1982
51:24was thought to occur
51:25only once in a century.
51:31But then,
51:32an even greater event
51:33struck a mere
51:34fifteen years later,
51:37provoking the question,
51:38is there a connection
51:41between El Niño
51:42and the gradual warming
51:44of the Earth's atmosphere?
51:48There's the whole
51:49global warming issue.
51:51I mean,
51:51we're doing something
51:51to the planet,
51:52there's no doubt about that.
51:53What the consequences
51:54will be,
51:55we don't have any idea.
51:57It's plausible
51:58that change in character
52:01of El Niño events
52:02may be related
52:03to global warming,
52:05but there are also
52:06other possibilities
52:07that can explain
52:08the intensity
52:09of this event
52:09or some of the
52:10unusual characteristics
52:11of El Niño's
52:12in the past
52:12ten to fifteen years.
52:14The jury is still out
52:15as to what the impacts
52:17of global warming are.
52:20Beyond global warming,
52:21many questions remain.
52:26Will anyone ever be able
52:28to precisely predict
52:29when the next El Niño cycle
52:31will begin?
52:31where it will hit
52:34and how hard
52:36it will strike?
52:50Will Mike McFadden
52:51and his colleagues at sea
52:52discover what triggers
52:54an El Niño
52:54and how the seeds
52:56of its destruction
52:57are sown?
53:00Will the Pacific
53:01ever reveal
53:02its long-held secrets?
53:07When I'm looking
53:08at the ocean
53:08out on the ship,
53:09I'm really not looking
53:10for anything in particular.
53:11It's more a contemplation.
53:14It's kind of immersion
53:15in the environment
53:16of the sky
53:17and the sea
53:18and the waves
53:19and the wind
53:19and understanding
53:21that scientific progress
53:22is based
53:23not only on the analysis
53:25of hard numbers
53:26but sort of the intuition
53:28you gain from being there
53:29and understanding
53:31the things
53:32that you really can't quantify
53:33or measure directly.
53:38The only certainty
53:40in this ocean-born mystery
53:42is that these scientists
53:43will soon have another opportunity
53:45to test their theories
53:46because inevitably
53:48El Niño will return.
54:08When it does return,
54:10will you be ready?
54:11Log on to the ultimate
54:13El Niño guide
54:14on NOVA's website
54:16at www.pbs.org
54:19To order the show
54:35for $19.95
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54:45can solve the mysteries
54:46of our world,
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56:04This is PBS.
56:13This is PBS.
56:17Next time on NOVA,
56:19two killer quakes
56:20exactly one year apart.
56:23In Japan,
56:24deaths in the thousands.
56:26In California,
56:27damage in the billions.
56:29Most frightening of all,
56:30the quakes happened
56:31at unlikely places.
56:33And chances are,
56:34they'll happen again.
56:35Are these seismic hot spots
56:37doomed?
56:38The day the Earth shook.
56:40That's next time
56:41on NOVA.
56:41て the way Impey
56:43you
56:46you
56:48So let them be
56:50there.
56:52I've got a
56:53love and
56:54in the winter.
56:55From the
56:55a
56:57love
56:58you
56:58like
56:59dozens
57:00and
57:00to
57:01see you
57:01here.
57:02Come on peace.
57:02Come on to
57:03See you
57:04like this
57:04thumbs up.