Is the Arctic melting? An 85-year-old Alaskan betting contest offers
some clues to the future.
Sagarin, a marine biologist at Stanford University who
studies climate change, was in Alaska to investigate tide
pools. Taking a break on the beach, he learned of a contest
called the Nenana Ice Classic from reading a Lonely Planet
travelers guidebook. Each spring, hordes of Alaskans
place bets on the date and time a giant nine-legged
contraption will fall through the frozen ice of the Tanana
River. Last year, eight lucky winners split $308,000.
Sagarin realized that contest officials might have kept
spring ice breakup records for the past 85 years, down to
the exact minute. Their records, he recognized with
excitement, could help reveal whether global warming has
affected the Arctic by showing if spring has been coming
earlier. As soon as Sagarin returned home, he called the
Nenana Ice Classic contest headquarters. Officials there
gladly mailed him copies of their recordsand the
documents were everything he had hoped for.
Sagarin's use of obscure historical records to answer a
current research question is a prime example of a
little-known science called phenology. Long a neglected
backwater, phenology is the study of recurring natural
events such as flowering, breeding, and migrationor,
in Sagarin's case, spring ice breakup. Relying upon old
diaries or logs that tracked seasonally repeating phenomena
has its own peculiar strengths and weaknesses. But today,
such records are taking center stage as a surprisingly
powerful tool in the study of climate change. For all their
high-tech satellite studies of the planet, scientists still
need the recollections of the long dead to understand
global warming. Such insights are critical because global
warming could disrupt weather patterns and ecosystems
across the planet.
The Arctic especially fascinates global warming
phenology researchers, because that's where the world's
largest temperature increases have occurred in recent
decades. Studies indicate that the Arctic has just gone
through its warmest century in 400 years, with plant
activity in the far north jumping 11 percent during the
final decades of the twentieth century. One climatology
researcher predicts that global temperature increases in
this current century will be double that of the last, and
the Arctic will be hardest hit.
IN THE WORLD OF PHENOLOGY, discovering historical data to
study requires more than a modicum of serendipity. After
all, how do you know where to look to find records in the
first place? Recently for instance, John Magnuson, a lake
ecology researcher at the University of Wisconsin in
Madison, learned of a document listing 100 years of freeze
and thaw dates for a lake in Maine. The record was hanging
in a restaurant foyer, next to a board filled with business
cards. "It's like treasure hunting," Magnuson explains.
"Sometimes you find the records by accident."
That was certainly the case with Sagarin and the Nenana
Ice Classic. The beauty of the annual contest is that it
relies on the gambling compulsions of more than 100,000
Alaskans. To keep the contest fair and accurate, the rules
haven't changed in 83 years. The yearly tradition is so
popular that it was written into state law in 1959.
The Ice Classic traces its beginnings to a group of
engineers who overwintered in 1917 in the town of Nenana,
55 miles southwest of Fairbanks. They were waiting to build
a railroad bridge across the Tanana River. Until the river
melted, they couldn't finish. Pooling their money, $800 in
all, they placed bets on when the river's three-foot layer
of ice would break under the pressure of upstream waters.
Being engineers with too much spare time on their hands,
they built a wood contraption that was cabled to an onshore
clock to mark exactly when the ice broke up. Though they
called a 'tripod,' the 30-foot device actually has nine
legs rooted in the river's ice.
The spring thaw officially arrives when the
black-and-white-striped tripod collapses through the ice or
drifts far enough to move its cable a hundred feet, yanking
the onshore clock to a stop. Sometimes, the tripod slowly
sinks in rotting ice; other times upstream debris knocks it
down. Either way, the lucky winner is the one who guesses
the day, hour, and minute when the clock halts. Then Nenana
waits another year to cut another tripod from the woods.
"Nobody has no idea when the breakup is gonna
come," says Perci Dike, a Nenana local. "If I
did, if I had some idea, I would have win the dang thing
there years ago."
As a safeguard against cheating, a 24-hour watch is
stationed at the river during prime ice break days, usually
April 25 to May 10. Along with that precaution, the tripod
design and contest rules all make for a precise scientific
experiment, says Sagarin. In fact, the Ice Classic has
provided some of the most trustworthy data available yet in
the field of phenology.
Every phenological experiment starts with a scientist
trusting the stories of people who may not be the most
accurate observers of nature, and that raises some
potential problems. How does the researcher know that an
observer's records are true? Take the example of an Arctic
island explorer named Joseph Dewey Soper, who recorded when
he sighted caribou throughout the year for the Canadian
government. According to Soper's journal, he didn't see any
caribou for seven months in 1931. But his documents
neglected to mention that he couldn't travel during that
time because of a knee injury from slipping on sea ice,
Canadian researchers learned.
Another difficulty is how recordkeepers define when a
noteworthy event has occurred. For example, a tree could be
said to have new leaves when there are visible buds, or
when the first leaf is fully grown. New observers who take
over a recordkeeping tradition may do things differently if
the rules aren't clearly defined when the old observers
By contrast, the records from the Ice Classic sounded
too good to miss out on. Within two hours of receiving the
documents, Sagarin plotted a graph with the ice breakup
data--and found he had hit the jackpot. The results showed
that spring melts in Nenana today come on average five and
a half days earlier than in 1917.
Sagarin wondered whether other data existed that could
back up his results. He attempted to find snowfall,
rainfall, or air temperature records from weather stations
in Fairbanks and Nenana, but ran into the sorts of problems
that kill many phenological experiments. Nenana had not
taken any measurements during many of the last 85 years.
Records from Fairbanks, on the other hand, were not very
helpful, in part because the station had moved once. For
Sagarin's desired level of precision, snow or rainfall
records taken in more than one location were useless.
And since Fairbanks had grown considerably over the
years, the records were doubly damned. City growth creates
a 'heat island,' where buildings, pavement, and cars raise
local temperatures. Temperatures in town didn't reflect
nature. At any rate, good temperature recordstaken
with the same thermometer, at exactly the same time of day,
every single dayare rare to find.
Another type of seasonal data that researchers can
sometimes track is the sudden greenery of spring, a global
phenomenon they call the "green wave." (A classic
example is the "cherry blossom front" that moves
from south to north in Japan.) Investigators use satellite
images to register spring's march across the globetwo
swaths of green burning their way toward the Arctic and
Antarctica. But since accurate images date back only 20 to
30 years, theyre of limited help in following
longterm changes. Thats why scientists have fallen
back on phenology records of all kinds.
On the ground, old journals recording the first buds of
spring cant offer clearcut proof of climate warming
either, though. The timing of plant buddings depends on
more than just ambient temperature. Buds "count" warm days
and then burst open, but a mild winter can confuse them and
delay their opening.
All in all, says Sagarin, compared to the other
methods, a more accurate way of measuring longterm
temperature change is to study the freezes and melts of
lakes and rivers. It's much easier to trust someone to
write down when the ice melted than to track temperatures,
he says. Magnuson, the lake ecologist, agrees. "In
many places in the world, we have lake and river records
going back 100 to 150 years," he says. "But a
single record from a single point does not convince one
that the world is getting warmer. It is critical to have
long-term records from around the globe." Magnuson has
compiled 39 different records that list ice breakups and
melts in the northern hemisphere, from Asia to Wisconsin.
His studies, like Sagarin's, show that spring ice melts are
occurring sooner and winter freezes are coming later.
Ironically, the researchers note, global warming may
destroy some phenological sources of data, as lakes and
rivers at lower latitudes fail to freeze in warmer years.
For instance, one of the longest running sets of historical
records has tracked the freeze dates of Lake Constance, in
Europe, for 1200 years. The logs belong to two churches
separated by the lake; one sits in Germany and the other
lies just across the border in Switzerland. Their chapels
share a single Madonna statue. When the lake freezes,
whichever chapel has the Madonna carries it across to the
other. Unfortunately, the lake doesn't freeze every year.
In some centuries, the lake didn't freeze at all. During
warm periods--which experts expect to see more of--the
record can't give enough information to measure climate
Scientists focusing on long-range bird migration
patterns will face a similar problem as global warming
speeds the arrival of spring. In the Netherlands,
researchers have been tracking climate change by applying
phenology to 20 years of records on the egg-laying habits
of the pied flycatcher. Normally, at a set time before the
start of spring, the birds fly north from dry tropical
forests in Africa to Europe. They lay their eggs to
coincide with the blooming of spring foliage that serves up
a peak of insect abundance.
But with spring arriving sooner and sooner over the
last 20 years, the timing of this bug feast has been moved
up as well. As a result, the flycatchers have been laying
their eggs on earlier and earlier dates. However, they're
can't adapt forever. Many already are migrating to Europe
too late to take advantage of the insect feast. Eventually,
the birds may reach a point beyond which they can't lay
eggs any earlier in the year, or possibly even die out;
researchers have already begun to detect a decrease in the
numbers of nestlings. Like a lake refusing to freeze, the
spring breeding of flycatchers could become an imprecise
record of climate change.
PIED FLYCATCHERS AREN'T THE ONLY ONES having trouble with
timing. Just about when Sagarin was going to publish his
findings, he realized a major problem with his calendar was
skewing the results. Wall calendars pretend that years are
365 days long, but the true solar year (the time it takes
for the earth to go around the sun) is actually about a
quarter of a day longer. Every fourth year, we add an extra
leap day in February in sloppy compensation. Even so, by
the end of a century, the calendar can still be off by
almost a whole day.
By Sagarin's reckoning, he is the first researcher in
phenology to notice this problem with records using years
that start on New Years Day. He proposes a solution:
To reduce the discrepancy, researchers could start their
year at the vernal equinox, the first day of spring when
day and night are the same length.
The bias, however small, is real. Other researchers in
the phenology world are taking Sagarin's criticism
seriously. But not everyone agrees that the vernal equinox
method is the best solution. Magnuson, for one, is
considering whether to reorganize his own research using
the winter solstice, the moment when the sun is farthest
from the equator. Beyond accounting for leap years and
historical calendar shifts, he hasn't applied any calendar
corrections to his results. But in the worst case, his
results are probably only a day off from Sagarin's.
At any rate, Magnuson likens the impact of Sagarin's
suggestion to a group of people timing a race. Even if
everyone's stopwatches aren't set to the right time, they
can still tell who crossed the finish line first.
Regardless of the exact timing of dates, the results from
phenology studies still point to a strong global warming
In the end, the experts say, phenology might well be
one of the best ways to truly nail down the case that
global warming is real. Handscrawled journals and logs from
the past have provided a wealth of evidence to choose from,
whether they come from priests, naturalists, or gamblers.
So far, ice breakup records like the one Sagarin stumbled
upon are providing some of the clearest proof yet of
worldwide climate change. And as the years go on, the
Nenana Ice Classic could show the fallout of global warming
even more dramatically. That is, if the river is still
freezing a century from now. Just don't bet on it.