Is there an El Niño in your
future or just a bad hair day?
There is a phenomenon afoot, and you'd have to have been locked in a
closet the past six months not to have noticed. Actually there are two phenomena:
the physical one we call El Niño and the media blizzard it has spawned.
The two are not necessarily related nor is it clear which is the more dangerous.
The physical El Niño is, among other things, a warming of the
waters of the equatorial eastern Pacific Ocean. It has been blamed for an
astounding variety of events from last summer's catastrophic floods in eastern
Europe to the prolonged dry season in Indonesia to, no doubt, the Braves'
failure to win the National League Championship. The warming is one phase
of an irregular cycling of events along the equatorial realm known as the
El Niño-Southern Oscillation (ENSO). The ENSO acronym illustrates
our present understanding that the phenomenon is both oceanographic (El
Niño) and atmospheric (Southern Oscillation) in origin and effect.
The opposite end of the cycle, when the eastern Pacific is unusually
cold, is called La Nina. It too has a list of global climate effects. As
complex as ENSO is, we now understand it well enough to be able to predict
confidently the onset of the warm phase and give reasonable warning to those
regions likely to feel its effects.
The media blitz surrounding El Niño is far more difficult to predict
and has significantly broader and longer-lasting consequences. As a general
rule, scientists know they're in over their heads when their research specialty
becomes the subject of a Dave Barry column and is summarily explained away
as a combination of espresso machines and whale snot. This is not quite
what our science mavens had in mind when they directed us to spread the
gospel of science's role in the human condition, but it had to happen.
El Niño has become a buzzword in the buzzword center of the universe.
It's short, rather catchy as buzzwords go and exotic. Exotic is especially
important when it comes to laying blame-America's new pastime. In the world
of weather it's as good a scapegoat was we're likely to get, short of the
impact of an asteroid the size of Macon-but that's a separate report. Even
though there is some correlation between the El Niño of Barry's column
and this year's weather, the recent blame is only partially deserved.
Climatologists base El Niño correlations, known as teleconnections,
on statistics, painting their forecasts in terms of seasonal probabilities.
The general public doesn't understand probabilities, choosing either to
ignore or to misinterpret probability-based phenomena. Do you, for instance,
really know what a forecast calling for "a 60 percent chance of rain"
means? Does anybody really know what a 60 percent chance of rain means?
Actual government forecasts of expected El Niño effects on Atlanta-area
weather might say, "Mid-latitude low pressure systems tend to be more
vigorous than normal in the Gulf of Mexico and along the southeast coast
of the United States, resulting in wetter than normal conditions in that
region." This forecast covers the winter months of December, January
and February. This is not quite the same as "Run inside, Helen, there's
an El Niño coming up the street!"
Here's the problem: it rained all yesterday, is worse today and the forecast
calls for two more days of rain. Is this an El Niño storm? No. Will
climatologists attribute the winter precipitation total, higher in part
due to this storm, to El Niño? Yes. There's an important distinction
to be made between weather and climate as well as between direct and indirect
Weather is what it's like when you step outside; climate is what it's
been like in recent history, usually 30 consecutive years. One day's storm
gets blurred into seasonal norms.
El Niño's tropical effects are significantly different than its
effects outside the tropics. Because we live outside the tropics, all El
Niño teleconnections are indirect effects: the weather system moves
pools of warm water in the tropics, which moves pools of water outside the
tropics, which affects the speed, shape, and location of the polar and subtropical
jet streams, which alters the surface storms that bring our winter precipitation.
Within the tropics the effects are more direct. Thus Indonesia's prolonged
drought is a direct effect of El Niño, as is the storm that floods
the coastal desert of Peru, which typically gets a cupful of rain in a good
year. And if Peru can have an El Niño storm, then why can't the greatest
nation in the world, for goodness sakes? In a way, we're seeing the effects
of our over-efficient news system, which can show the floods in Somalia
and the haze in Indonesia as they occur. Modern telecommunications have
effectively eliminated time as a news factor and, in doing so, have removed
distances as well. If it can happen there, why can't it happen here?
Few Americans seem to know enough physical geography to understand how
weather and climate vary across the globe and through the seasons. So we
wind up blaming climate effects for specific disasters and mixing tropical
causes with extra-tropical events.
The situation boils down to an exercise in communication. The physical
scientist predicts a wetter, more turbulent winter, and the public sees
a disaster coming up the street. The communication is there-and I believe
the broadcast and print media do a good job informing the public-but, understandably,
there are different perceptions of what is being communicated.
This is based partly on a general lack of understanding of our physical
world and partly on our human tendency to prefer the specific to the general.
Few people, for example, can warm up to a forecast of an 80 percent probability
of a 35 percent increase in winter precipitation over the norm. It's far
more satisfying to blame the storm that just ruined your best umbrella and
soaked your socks on that alien interloper El Niño and convince yourself
that somehow Peru is behind it all.
Nevertheless, the misconceptions and fun we're having with El Niño
this winter are similar to the difficulties before us as we begin to face
up to the onus of potential global warming. Back to you, Dave.
Woody Hickcox is senior lecturer in geosciences. For more information
about weather and climate conditions, he suggests visiting the Climate Diagnostics
Center web site at <http://www.cdc.noaa.gov/ENSO/>.
to February 2, 1998 Contents Page