Issue date: Aug 29, 1999
In this issue:
it getting hotter?
it getting wetter?
there more hurricanes?
there more tornadoes?
the weather getting worse?
Floods. Drought. Tornadoes. Now, we're in the heart
of hurricane season. Experts from the Weather Channel explain
what's really going on.
By Colin Marquis and Stu Ostro
last month, a heat wave sent temperatures soaring into triple digits
throughout the mid-Atlantic and Northeast, causing half a million
people to lose power and killing at least two dozen. Before the
month was finished, a second scorcher smothered the Midwest and
other parts of the country, this time killing more than 185 in the
deadliest heat wave there since 1995. And still yet in July, severe
thunderstorms dropped golf ball-sized hail and dumped 13 inches
of rain in Iowa, washing out bridges and railroad tracks, closing
dozens of roads and whisking an elderly man out of his car. Now,
we're in the heart of hurricane season.
The weather is awesome, frightening and spellbinding. It is a rollicking ride with no guarantee of safe return. But are we entering a unique era in weather history? Or are these events "business as usual" for Mother Nature?
As meteorologists with the Weather Channel, we've discovered
that the truth may come as a surprise to you: Some of today's weather
is wilder, and you can attribute part of that to nature. But blame
perception and mankind's actions as well.
Before, tornadoes ripped through Midwest towns, but consequences seemed more distant. Today, real-time multimedia communication means gripping images get beamed instantly from tornado alley into our living rooms - or PCs. It's as if we're all experiencing the bad weather, albeit vicariously. Furthermore, as the population continues to grow, more people and buildings get in the way of whipping winds and flooding waters.
So what's wilder out there: Our perceptions and behaviors? Or
the weather itself? Here's our take on what's really happening.
Is it getting
hotter? Yes. But not as much as you'd think. The Earth
has warmed about 1 degree Fahrenheit this century. We all have been
with long expositions on human-induced global warming, some of
them objective, others not. Inevitably, talk of global warming increases
during and just following extreme heat waves such as this past July's.
Weather is characterized by ups and downs, activity and monotony.
Extremes will always occur, and they do not necessarily foretell
of more ominous times to come. Globally, 1998 was the warmest year
on record, based on actual measurements as well as satellite data.
Still, it is important to remember that specific temperature records
over land date back only about 120 years, and data over the oceans
(70% of the globe) was quite sparse until about 25 years ago, when
satellites became more versatile. Therefore, precise measurements
of temperature do not extend far into the past, a mere drop in the
bucket when considering the realm of global climate change.
Is it getting
wetter? Yes. Tom Karl at the National Climatic Data Center
has found that much of the middle and upper latitudes of the earth
- most of the U.S., Canada and Europe - show increases of up to
20% this century. Most of that is due to an increase in very heavy
precipitation events. As global temperatures increase, one theory
goes, more water evaporates from the oceans. The increase in water
vapor results in heavier precipitation.
But, again, mankind's development is often its own enemy. As humans continue to develop land, laying concrete and asphalt along the way, it follows that water runoff problems would increase. Even with proper drainage systems, heavy rain accumulates much more readily on pavement than on soil. The scenes are repeated over and over - for example, in Dallas-Fort Worth and Kansas City earlier this year. The sky opens up and roads become torrents.
more hurricanes? No. The number of U.S. land-falling
major hurricanes (maximum sustained winds over 110 mph) has gone
down: 23 from 1940-69 and only 14 since 1970. However, damage caused
by hurricanes and other powerful ocean storms has increased markedly
since the '40s. Taking inflation into account, hurricane damage
costs went up from $36.8 billion from the years 1940-69 to nearly
$74.9 billion from 1970-96. So what's the deal? Again ponder the
explosion of increasingly more expensive coastal development. With
nearly uninhibited growth continuing along the nation's coasts and
the inevitability of strong ocean storms, losses will continue to
more tornadoes? Maybe. The number of reported
tornadoes in the United States has more than doubled from the '50s
to the '90s. 'Reported,' however, is misleading; the actual number
of tornadoes has not necessarily risen during that time. If a tornado
occurred and no one was around to see it or document its damage
path, then for the purpose of official numbers, it truly did not
occur. Even today, there is evidence suggesting that many tornadoes
There are good explanations as to why reported tornado numbers have risen so dramatically. Simply put, there are more people to witness tornadoes. Then consider the X factor: storm chasers. Virtually non-existent in the '50s, there are now hundreds who tote palm-held camcorders into the Plains to tape the Big One. It only makes sense that numbers of reported tornadoes are way up.
In the last few years, tornado-related deaths in America have risen. That's because a few tornadoes have hit densely populated communities. Of the more than 1,400 reported tornadoes and 130 tornado-related deaths in 1998, four twisters were responsible for 82 of the fatalities. Bottom line: Tornadoes can be frighteningly fierce and although the probability that one will hit a densely populated region is small, it can and does happen.
When taking a peek at the more distant past, Richard Alley from Penn State University discovered through ice-core measurements that global temperatures and precipitation in the last few thousand years have been as steady as any time during the last 100 millennia. He also found that large swings in temperature (15 degrees Fahrenheit) and wet weather occurred on a regular basis prior to the recent quieter time. Perhaps more interesting is that these swings, which happened long before humans had a chance to influence the environment, typically occurred within a 10-year period, indicating that drastic climate change can occur through natural means, and quickly.
This evidence raises an interesting and provocative idea. Perhaps wilder weather is actually more typical than benign weather.
Whether humans are contributing to climate change or not, maybe
the pendulum is beginning to swing back - toward the wild side.
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