FireandRain_1998

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1998 Fire and Rain. Time International 20 Apr. 1998: 34
Fire and Rain
El Nino's fury can still be seen in the drought and raging blazes of Borneo. Now Asia must
prepare for a possible deluge from La Nina
For months almost no rain has come to Teluk Pandan, a dusty hamlet in Indonesia's East
Kalimantan province. Rice can't be planted. The local river is now a stagnant creek backwashed
with seawater. Banana trees are withering. And the smell of burning tinder fills the air, as flames
lick the bone-dry forests of the island of Borneo. Says Suwarjo, a villager who has been trying to
put out a blaze near his home: "This is a harvest of fire."
Indonesia's inferno is but one of the bitter effects of the phenomenon known around the world as
El Nino, the mysterious, periodic warming of Pacific Ocean waters that leads to nasty extremes
in the weather. The latest coming of El Nino is among the worst on record, and the impact has
varied wildly from one region to another. While floods have soaked the Americas and deadly
storms have pelted China, droughts have parched Australia and fueled fires in Southeast Asia
and Brazil.
But as bad as the past year has been, the future may hold no relief. The period following an El
Nino often brings a cooling of those same Pacific seas--a climatic pattern known as La Nina,
which generally produces sharp reversals of weather patterns around the globe. Some scientists
now say 1998 could witness an unusually strong La Nina, and Asia is bracing for its onslaught.
In Indonesia, meteorologists believe that when torrential rains fall on ground charred by more
than 1,000 forest fires, the downpour could produce flash floods, severe soil erosion and the
depletion of fish stocks as toxic ash seeps into rivers, lakes and coral reefs. In the Philippines,
President Fidel Ramos has already ordered officials to unclog and repair drainage and floodcontrol systems nationwide to prepare for floods that could destroy more than one million tons of
rice. Says Victor Ramos, the country's Environment and Natural Resources Secretary: "We are
more worried about La Nina than El Nino."
That's saying something, considering the toll that La Nina's temperamental brother has taken so
far. Last fall a vast swath of Southeast Asia was immersed in smoke from a previous round of
Indonesian forest fires: hundreds died and tens of thousands were stricken with respiratory
ailments. Damage caused by the haze alone exceeded $1 billion, and now smoke is spreading
once again. Meanwhile, famine has struck the region. More than 650 people have perished from
hunger in Indonesia's Irian Jaya province as a result of crop failure, and this year dry conditions
and fire have brought at least 60,000 close to starvation in East Kalimantan. In the Philippines,
agriculture losses and malnutrition are mounting, as hordes of rats have surfaced from the
scorched earth to infest farmlands. Heavy rains have hit coastal China and Taiwan, where the
worst typhoon in a decade blew through last summer, killing more than 200 people.
All the devastation has added a new urgency to a long-running scientific mission: the quest to
understand El Nino and La Nina. This cycle of disturbances may already be the most studied
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weather phenomenon of all time. For months, and in some cases years, meteorologists have been
poring over weather maps, running supercomputer simulations, studying coral reefs, tree rings
and glacial ice--all in an effort to probe the dynamics of water temperatures in the Pacific.
Some researchers want to learn what causes El Nino/La Nina and what keeps the cycle churning.
Others want to measure the effect on human life. To that end, the U.S. National Oceanic and
Atmospheric Administration announced in February that it is setting aside $2.1 million to study
the impact of the latest flurry of El Nino-related storms. In November, the Philippines hosted the
Asia-Pacific El Nino Water Summit, which examined the public health risks for the region's
affected countries. In early February, the Bangkok-based Asian Disaster Preparedness Center
held a conference in the Thai capital, with meteorologists, oceanographers and climatologists
brainstorming and sharing information. Even Japan, which is only indirectly affected by El Nino
because of its location far north of the equator, has set up an El Nino Monitoring and Prediction
Center at the Japan Meteorological Agency to project climate changes using a supercomputergenerated model.
At the same time, El Nino gives scientists a rare chance to study a phenomenon that transcends
the short-term weather forecasts that are the bread and butter of meteorologists. In many ways,
El Nino may be a test case for the kind of large-scale weather effects some scientists predict will
accompany the climate changes caused by global warming.
Like global warming, El Nino--or rather, the climate cycle that produces El Nino--does not
generate weather per se: rather, it alters the context in which weather takes place. The distinction
here is a critical one. "Climate," as social scientist Michael Glantz of the National Center for
Atmospheric Research, likes to say, "is what you expect. Weather is what you get." Sometimes
there can be a wide gulf between the two. In Australia, for example, El Nino caused extremely
dry conditions that had farmers fearing disaster. But as it turns out, some rain did fall--just in
time to rescue the wheat harvest. Does that mean the drought predictions were wrong? Not at all,
says Nicholas Graham, a climate modeler at the University of California at San Diego's Scripps
Institution of Oceanography. Think of what El Nino does as the equivalent of rigging a roulette
wheel so that it comes up black 40% of the time and red 60% of the time, Graham suggests. "Just
because it comes up black once," he says, "you don't conclude the roulette wheel isn't rigged."
In trying to improve their power of prediction, researchers are building on a scientific
investigation that began in the 1920s, when the British meteorologist Sir Gilbert Walker linked
swings in atmospheric pressure over the Pacific to a calamitous failure of the Indian monsoon 50
years earlier. In the 1960s, UCLA meteorologist Jacob Bjerknes suggested that El Nino was
governed by the same swings in atmospheric pressure. The way El Nino works, scientists are
now convinced, is that high pressure in the eastern Pacific sends trade winds blowing to the
West. Because these winds push water before them like an invisible plow, the sea's surface
actually measures about a half-meter higher around Indonesia and Australia than it does off the
coast of Peru. When the pressure drops and trade winds slacken, the water sloshes back downhill,
to the east.
This eastward flow is central to the physics that drive El Nino, says Scripps' Nicholas Graham.
The sloshing sends waves across the ocean like ripples in a pond. These waves, in turn, push
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down on the so-called thermocline, a layer of cooler water that normally mingles with the
warmer water at the surface. As the thermocline sinks to greater depths, the mixing stops,
temperatures at the sea's surface rise, and an El Nino begins.
These ripples can be thousands of kilometers long, but since they travel 30 m or more beneath
the surface they are hard to detect directly. So scientists use satellites to pick up the subtle
undulations in sea level produced as the ripples pass by. That's how NASA oceanographer
Anthony Busalacchi could see early last year that swarms of undersea waves had started to head
out across the Pacific toward the coast of Peru; he followed them as they slammed into the
continental shelf, then split, heading sharply south toward Chile and north toward Alaska. The
warm water created by the south-moving ripples created a heat wave that sent residents of
Santiago flocking to nearby beaches in the middle of their winter, while the north-moving waves
triggered a sharp rise in ocean temperatures off the U.S. West Coast, delighting sportfishermen
by attracting tropical species like marlin to usually frigid waters.
These subsurface waves explain more than the origin and propagation of El Ninos. They also
explain how El Ninos end. When the waves first hit the South American coast, some reflect
back, like sound bouncing off a wall. When the reflected waves reach Asia, they rebound again.
But this double bounce inverts their effect: instead of depressing the thermocline, these twicereflected waves now lift it up. Cool water dilutes the warmer liquid at the surface, causing a
temperature drop in the eastern Pacific--and that decrease is known as La Nina. Thus, observes
Ants Leetmaa, director of the National Climate Prediction Center, "each El Nino contains the
seeds of its own destruction." For every Nino there's a Nina.
How long this cycle has been operating, no one really knows. Finding out might seem to be a
hopeless task, considering that the phenomenon was discovered only about a century ago by
Peruvian fishermen. (It was they who called it El Nino, the Spanish name for the Christ child
whose December birthday occurs at the peak of the disturbance.) But late last year, Columbia
University oceanographer Richard Fairbanks was floating in the equatorial Pacific gathering data
that could tell researchers about El Ninos going back thousands of years. Working aboard the
research vessel Moana Wave, Fairbanks spent weeks at El Nino's very epicenter, a patch of
ocean near Christmas Island in the Republic of Kiribati, 2100 km from Hawaii. Using a powerful
oil drill, he and his colleagues repeatedly bored into ancient reef beds buried beneath the sea
floor, pulling up chunks of coral as white as sun-bleached bone.
Corals, it turns out, are like miniature thermometers and rain gauges. When water temperatures
rise, these small creatures incorporate less strontium into their skeletons than they do under
cooler conditions. Their oxygen content, meanwhile, records salinity swings, which in turn can
be used to estimate rainfall. And warm temperatures and heavy rainfall--here, at least--are the
telltale markers of El Nino.
Corals are not the only recorders of climate history. Jay Noller, a geomorphologist from
Vanderbilt University in the U.S., has been studying ancient sediments from Peru's northern
desert, which is among the driest spots on earth--except during El Nino years. Then and only
then, torrential rains from a succession of storms compact surface dust into a layer of fine, red
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soil. From the age of the soils he has examined so far, Noller concludes that the El Nino cycle
has been operating for at least 2 million years, and probably much longer.
But that doesn't mean it has always oscillated, as it does today, roughly every two to seven years.
Fairbanks thinks the current pattern may have switched on between 14,000 and 9,000 years ago,
when rising sea levels swamped a landmass that included modern-day Australia and Indonesia.
Such a continent could have stabilized atmospheric pressure, keeping El Ninos from ever getting
started. Whether this hypothesis is correct, no one yet knows. But the bits of coral Fairbanks and
his team wrested from the submerged reefs around Christmas Island nicely bracket the period in
question.
Trees too can faithfully preserve evidence of long-past climate patterns. David Stahle of the
University of Arkansas Tree Ring Lab recently presented data derived from teaks in Java and firs
in Mexico and the American Southwest that date back to 1706. The thicker the trees' growth
rings, the more rain fell that year. According to Stahle, "it looks as if a substantial shift occurred
after 1880." After that date, the rainfall patterns typical of El Nino start to recur on average every
4.9 years instead of every 7.5, while patterns typical of La Nina show up at 4.2-year intervals
versus once a decade.
An even longer-term perspective comes from paleogeologist Lonnie Thompson of Ohio State
University, who specializes in extracting climate histories from mountain ice. Like trees and
corals, ice grows in distinct layers whose thickness depends on the snowfall in a given year.
Drilling into the Quelccaya ice cap in the Andes of Peru, Thompson has detected the short-term
precipitation swings typical of El Nino and La Nina.
Out of all this information, a crude picture begins to emerge. It appears the El Nino cycle is more
variable than scientists previously imagined, subject to protean swings of mood that last from
decades to hundreds or even thousands of years. To account for this eccentric behavior, many
scientists invoke the science of chaos, which says slight differences now--a barely perceptible
increase in wind speed, for example--can lead to a dramatic change down the road. The El Nino
cycle may resemble a chaotic pendulum whose swings never retrace the same path. Yet there is a
rhythm to the swings, like a jazzman's improvisations, endlessly circling a central theme. Chaos
routinely pops up, in fact, when climate modelers Stephen Zebiak and Mark Cane from
Columbia University's Lamont-Doherty Earth Observatory run computer simulations of the El
Nino cycle. All the virtual El Ninos resemble one another, says Zebiak, but of thousands of
simulations, no two evolve in precisely the same way.
Just to make things more complicated, it now seems that some of the variations in El Nino cycles
come from outside, imposed by other components of the world's intricately interconnected
climate system. "We've been treating El Nino as a purely tropical problem, but what if it isn't?"
asks Princeton University oceanographer George Philander. What if some external force--a
wind-driven current, say, that sweeps warm water down from the north--were to make it easier
for the next El Nino to start? Such a current, Philander thinks, could explain the unusual spate of
El Ninos that marked the first part of this decade. Think of the cycle as one of the strings on
climate's violin, he suggests. "When something changes the tension on the string, the frequency
of the vibration also changes."
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External forces may also help explain why El Nino has a different impact on the weather from
one cycle to the next. Recently, for example, Ed Cook of Lamont-Doherty and Julie Cole of the
University of Colorado used tree rings from hundreds of sites to see how El Nino affected North
America in the past. Before 1920, they found, El Nino appears to have buffeted a much larger
region of the U.S. than it does today, channeling winter rain and snow all the way up into the
Great Lakes and Great Plains. Afterward, however, its sphere of influence retreated to northern
Mexico and the American Southwest. Why the shift? It may be, Cole suggests, that El Nino is
overlaid on a different climate cycle that is even more important.
One prime suspect is something known as the Pacific decadal oscillation, a long-term fluctuation
of water temperatures in the northern part of the ocean. Since 1977, say researchers from the
University of Washington, that phenomenon has been locked into a mode that makes winters in
northwestern U.S. warm and dry, just as El Nino tends to do. But according to climatologist
Nathan Mantua, the Pacific oscillation was in a different phase between 1947 and 1976, and as a
result winters in Washington State were cold and rainy. Yet another player in the El Nino drama
is a cycle in the tropical Atlantic that involves a flip-flop between twin pools of water--one
warm, one cool--that sit on opposite sides of the equator. Depending on the configuration,
farmers in northeastern Brazil could either suffer greatly at the hands of El Nino or feel very
little at all.
While all these climate cycles seem to involve both atmosphere and oceans, more and more
scientists are abandoning their long-held belief that air currents run the show. The atmosphere is
fickle, they observe. Storms form, then quickly dissipate, so whatever information they contain
about the conditions that created them is quickly lost. By contrast, ocean gyres--surface currents
that follow a sweeping circular route--take anywhere from 10 to 20 years to complete a single
journey, making them perfect vehicles for transmitting messages into the future. With the
exception of the tropical Pacific, unfortunately, the oceans are less well monitored than even the
moon's surface. The changes they undergo, moreover, take longer than any scientist's lifetime.
That's why corals and tree rings and ice cores are so important. They are like a tape recording of
the various instruments in the climate orchestra, ranging from El Nino's high-frequency violin to
the deeper cello and bass tones struck by longer-term cycles. By studying the hidden rhythms in
these signals, scientists may finally be able to see how the parts fit together, sometimes
harmonizing, sometimes clashing.
Over the next few years, researchers hope to shed light not only on El Nino's past but on its
future as well. For if the atmosphere warms because of the buildup of greenhouse gases, the El
Nino cycle could very well change. But how? Would it speed up, slow down or stop entirely?
Given the present state of knowledge, no one can tell for sure. We will never have a complete
picture of the planet's complex, unpredictable climate patterns, but as this scientific quest moves
forward, we could get useful glimpses of what lies ahead.
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THE WORKINGS OF EL NINO AND HIS SISTER
El Nino is a shift in ocean temperatures and atmospheric conditions in the tropical Pacific that
disrupts weather around the world. It all starts when eastern Pacific winds head west, plowing
ocean water in front of them. When these winds ease, the waves return east, pushing down the
thermocline, a layer of cool water that normally dilutes the warmer ocean surface. As surface
temperatures rise, weather patterns change. But El Nino eventually brings about its own
destruction. When the waves bounce off South America and then Asia once again, their impact is
inverted. As a result, the thermocline is pushed up, and the ocean's surface cools. That gives rise
to La Nina, whose moods may be just the opposite of those shown by her temperamental brother.
Heat waves may turn into cold spells and droughts into deluges.
IMPACTS AROUND THE WORLD
1. THE NORTHERN U.S.
This was the El Nino that stole Christmas. New York City was a balmy 4.4[degrees]C
warmer than usual for the month of January.
2. MEXICO
In December, snow fell in Guadalajara for the first time since 1881.
3. BRAZIL
Environmentalists fear the extended drought will turn the fragile Amazon into a tinderbox
and speed the already rapid destruction of the rain forest.
4. CENTRAL PACIFIC
At the epicenter of El Nino was a bumper crop of tropical cyclones; eight in 1997,
compared with two the year before, ripped through the islands.
5. JAPAN
In December, Olympic organizers feared that El Nino would push snow away from
Nagano and spoil the Winter Games. By February, they were praying for a little less
snow.
6. CHINA
Intense storms raged across coastal provinces. Late-summer floods and landslides wiped
out villages and killed more than 200.
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7. INDONESIA
The worst drought in 50 years has fueled fires that have claimed at least 400,000 hectares
of forest. Malnutrition has killed hundreds of people, and, like last year, a haze is
spreading over the region.
8. INDIA
El Nino confounded predictions that it would adversely effect the vital monsoon season.
The state of Tamil Nadu received one of its highest recorded rainfalls.
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