DANGER SIGNALS
Destructive Power Of Hurricanes On The Rise
In
June 2000, a team of American tourists, aboard the Russian icebreakers Yamal,
went to the North Pole and to their utter astonishment found a fresh water lake,
nearly 1.5 km wide, right at 90 degree N. When the news appeared in the New York
Times, experts readily declared it as another serious signal of global warming
and said that such an opening in the polar Parma-frost could have appeared
nearly 50 million years ago. They also pointed out some other danger signals of
global warming and said that in the past two decades, the average annual
temperature has climbed by as much as four degrees C in Alaska, Siberia and
parts of Canada and as a result, the sea ice in the polar region has come 40 per
cent thinner and now covers six per cent less area than in the 1980s.
Presently,
most of the scientists have raised their finger again towards global warming and
blamed it for triggering the two category five hurricanes, Katrina and Rita,
that lashed the American Gulf Coast within three weeks causing colossal damage
to human life and property. Like Katrina Hurricane Rita started as an unnamed
tropical depression in the Caribbean with wind speed of about 40 kmph. While
passing below Florida on 20 September, Rita was merely a category one hurricane
on the Saffir-simpson scale, with wind speed from 119 to 153 kmph. But on the
next day, it Ned into a category five storm with wind speed 250 kmph or more.
Most of the scientists agree that a warmer Gulf has fuelled both the hurricanes
to attain that severity. Peter Webster a scientist at the Georgia Institute of
Technology has discussed the matter in a paper that appeared recently in a
science journal.
In
general, hurricanes can form only over oceans that have surface temperatures
above 26 degrees C and , according to Dr. Webster, a rise in temperature above
26 degrees C might increase the number of storms, their severity and the
duration they last. He has analyzed satellite data for surface temperature of
six basins, namely (1) North Atlantic, (2) West Pacific, (3) East Pacific, (4)
South west Pacific, (5) North Indian and (6) South Indian Oceans and found a
significant rise in temperature in all but the South-West Pacific. He could have
been able to go back up to 1970, as before that satellite technology could not
attain perfection, and found that, since then the average ocean surface
temperature has risen by 0.5 degree C all over the globe.
But
while analyzing severe storms, he has found that only in the North Atlantic, the
number of such storms and their duration has increased considerably, giving the
impression that the number of storms is not directly linked to ocean warming.
More importantly, he has found that the most destructive hurricanes are steadily
rising. There were 44 category one storms allover the globe within five years
from 1970 to 1974, and the number declined to 29 in 2000 and 2004.
On
the contrary, there were 18 category four and five storms in 1970-74, and the
number increased dramatically to 37 in 2000- 04. Dr. Webster has also made
another striking observation though there has not been any consider able rise in
ocean surface temperature, there has been an unusual rise in category five
hurricanes in the South – west Pacific. In another paper in the same journal,
Greg Holland and Judy Curry of the School of Earth and Atmospheric Science at
the Georgia Institute of Technology have studied the frequency of hurricanes and
their intensities for the past 35 years. They have also come to the same
conclusion that the number of category one, two and three storms has fallen
slightly, while that of category four and five storms has climbed dramatically.
In
and around 1970, there were an average of 10 category four and five hurricanes
per year worldwide. But since 1990, the number has nearly doubled to 18. Or in
other words, the percentage of big storms has gone up from just 20 to 35. “We
have found a sustained increase in hurricane intensity over past 30 years all
over the globe”, says Dr Holland. “If 2005 goes down as the worse hurricane
season on record in North Atlantic, it will join 2004 as one of the most violent
ever. And these two seasons are part of train are increasingly powerful and
deadly hurricanes that has been playing out for more than ten years”, says Dr.
Curry “the so called once in a lifetime storm is not even once in a season any
more”, she adds.
In
another paper published in journal Nature in August 2005, Kerry Emanuel of the
Massachusetts Institute of Technology has surveyed nearly 4800 hurricanes in the
North Atlantic and North Pacific over the past 56 years. He has found no
increase in total number of hurricanes, but their power measures in terms of
wind speed and duration has jumped by 50 per cent since mid-1970s. “Globally,
we do not see any increase at all in the frequency of hurricanes. During past
ten years, number of hurricanes in the North Atlantic has certainly increased,
but at the same time their has been a corresponding fall in the number of storms
in the North Pacific”, says Dr. Emanuel “but the power of destruction of the
hurricanes has more or less increased by 50 per cent in the past 30 years.
Storms are getting stronger and they are lasting longer”, Dr Emanuel
continues.
It
is also important to note that a storm that does not heat a populous coastal
area often attracts little attention. For example, in the three weeks between
Katrina and Rita, five other hurricanes lived and died in the worm Atlantic
water without raising much hue and cry. It should also be mentioned here that
Katrina and Rita made headlines due to another reason. Apart from damaging human
life and property, they have hit the heart of the US oil industry. Nine oil
refiners with 33 per cent of US refining capacity where in Rita’s path and
they produce about 12 per cent of US gasoline. The area also produces about 20
per cent of US natural gas and the closer of these refiners and gas wells has
let to a lose of $4 billion. At the
same time, out of about 500 oil rigs operating in the region, 87 have been
evacuated leading to a lose of 1.4 billion barrels of crude oil production. To
major pipelines have also suffered damage.
The
city of New Orleans is surrounded by a 350-mile system of levees that hold back
the waters of River Mississippi and Lake Pontchartrain. When the levees failed,
80 per cent of the city area was flooded and some parts were submerged under 6
metres of water. According to a rough estimate, the damage caused by Katrina
stands at nearly $ 100 billion and the death toll could excide 10,000.
Hurricane Galveston in 1900 recorded the highest number of casualties
(8,000 to 12,000) and Hurricane Andrew in 1992 had caused the highest damage ($
44 billion).
Global
Warming Could Serious Damage In India
Many
apprehend that the worst is still to come. A group of scientists believes we
might have entered a new cycle of heavy hurricane activity after a relative come
over the past 30 years. In fact, environmentalists, for past several years, have
been warning that, “one of the first of most reliable sign of a
climatologically crash would be an upsurge in the most violent hurricanes, the
kind that in a suddenly warmer world”.
After
watching to Gulf Coast Hurricanes reach category five in the space of three
weeks even the skeptical scientists are starting to wonder whether something
serious might have been going on. “There is no doubt that climate is changing
and humans are partly responsible”, says Kevin Trenberth, head of the climate
analytics section at the National Centre for atmospheric Research (NCAR) in
boulder, Colorado. “The odds have change in favor of more intense storm and
heavy rainfalls”, says DR. Holland. “These are not small changes and we are
talking of very large change”, he adds.
A
group of scientists also believe that many other calamities related to global
warming are yet to show their faces. For example, the difference of temperature
between the topics and the poles generally drives the global climate system. The
excess heat that accumulates in the tropics is conveyed to the poles rough what
is known as the mean Conveyor, a vast deep-water current equivalent to 100
Amazon Rivers, while the rest of the heat is conveyed as energy in storms that
move towards to the poles. So, if the poles continue to warm faster than the
tropics, the vigor of the planetary circulatory system may diminish and
radically alter the prevailing wind, ocean currents and rainfall patterns. Or in
other words, alter the climate.
It
is now well known that carbon dioxide, nitrous oxide, methane and three other
gases, mostly by-products of burning fossil fuels and commonly known as
greenhouse gases, trap the heat emitted by the earth. This blanketed heat raises
the temperature of the earth and the phenomenon is known as the “greenhouse
effect”. In 1995, the global emission of greenhouse gases was about 6.2
billion metric tons and the figure climbed to 7.2 billion metric tons in 2000.
Since the beginning of the industrial revolution in the middle of 18th
century, the level of carbon oxide has increased by 30 per cent, nitrous oxide
by 15 per cent and methane by 100 per cent in the atmosphere.
At
present, the USA is the biggest emitter of greenhouse gases and 34 industrial
nations in the West, including of USA, are the major polluters. According to a
recent estimate by the UN, the emissions by this 34 nations of the past 100
years have already raised the global temperature by 0.6 degree C. It
should be mentioned here that a lowering of global temperature by three degrees
C bought the last Ice Age and without any greenhouse effect, the earth would be
cooler by 33 degree C. Experts believe that, if the emissions of greenhouse
gases is not curbed, the temperature of the earth may rise by 3.5 degrees C to 5
degrees C by the end of the 21st century. Due to global, warming the
moisture contained in the atmosphere has risen by 10 per cent in the past 20
years. Another study has revealed that water vapor in the air is rising at the
rate of 1.3 per cent per decade and the scientist agree that a high moisture
level in the air helps fuel violent storms associated with more rainfall and
consequent flooding. “During Katrina rainfall exceeded 12 inch at New
Orleans”, says Dr. Trenberth, adding, “More water vapor in the air triggers
killer storms and increases rainfall intensity”.
It
has been mentioned earlier that both Katrina and Rita began as mere tropical
depression and category one storms, but turned rapidly into devastating category
five in the Gulf of Mexico. So the question naturally arises ---- Why they
gained energy in the Gulf? Most scientists are convinced that a warmer Gulf is
the answer. “Warmer air can easily translate into warm oceans and a warm ocean
the jet fuel that drives the hurricane’s turbine”, says Dr. Curry. “The
Gulf is really warm this year, and it is just cooking those tropical storms”,
she adds. “In fact, when Katrina heat the coast at the end of August the Gulf
of Mexico was a visible hurricane refueling station with water up to three
degrees C higher than normal”, says an expert.
There
was another agent responsible for stimulating the hurricanes. Extending from the
surface to a depth of 600 m or more, three exists an U-shaped stream of warm
water that flows from the Yucatan straits to the Florida straits and sometime
reaches as far as the Mississippi Delta. Scientist calls it the loop Current. A
hurricane, while passing over this Loop Current gets an energy boost. Scientist
believes that both Katrina and Rita surfed it across the Gulf, picked up energy
and became powerful before slamming into the coastal states. Many capitals
apprehend that a warmer Gulf might have turned the loop even deadlier. “We do
not know the temperature within the Loop Current. It is possible that below that
surface, it is wormer than normal”, says Nam Walker, director of Louisiana
State University’s Earth Scan Laboratory.
But
there are skeptics as well; who try to convince that global warming has little
influence on climate change and other natural disasters. Chris Landsea, a
scientist at the National Hurricane Research Centre in Miami, believes that,
“Global warming may be boosting the power of Hurricane, but only a bit perhaps
by 1 per cent to 5 per cent. So, a 100 mph hurricane of today would be a 105 mph
hurricane after a century”. Stan Goldenberg, a meteorologist at the US
National Oceanic Atmospheric Administration in Key Biscayne, Florida, believes
that the present hue and cry is due to the fact that hurricanes are densely
populated coastal area and say, “the storm activity this year is not
necessarily higher in the previous year. It is just where there going “. Some
also try to argue that higher casualties this year are not due to increase
ferocity of the storms, but due to rapid increase of population in the coastal
areas of the Gulf. So, an expert says, “Between 1980 and 2003, coastal
population has jumped by 21 per cent in the USA. In Florida alone, the increase
was a staggering 75 per cent”. A few also try to push the idea that hurricanes
have not necessarily got more furious these days and despite perfections in
satellite technology and people are making error in measuring wind speed and
hence to determine the category of a storm. So Dr. William Grey, a climatologic
of the Colorado State University, says. “It is not easy to distinguish between
a category 3 and a category 4 storm, every today”.
Whatever
might be the arguments and counter-arguments of the experts and the scientists,
global warming has already started to show its teeth. Due to its influence
winter is coming late and spring is arriving nearly two weeks early in Canada,
and as a result of this late freeze and early thaw, the feeding time for the
polar bears has been reduced and they are migrating to the north. Forests in
Alaska are turning into marshy grasslands due to unusual melting of ice. Fishes
and birds, adapted to cold weather, have started migrating to the north and 1998
has been recorded as the hottest year in the history of mankind, followed
closely by 2003 and 2004.
So,
there is no doubt that the temperature of the arctic region is rising fast and
many apprehend that, if things are allowed to go as it is, the polar ice-cap
would disappear completely within 2080, leading to considerable rise in sea
water level, and hence the valuable coastal land all over the world would be
inundated. Experts also predict that cities like Mumbai, Hong Kong, Singapore
and New York would be flooded, considerable land mass of low lying countries
like Bangladesh would be submerged under sea water and small island nations like
Maldives would go into extinction.
For us, Indians, the phenomenon of global warming and the rapid melting of arctic ice is an extremely serious matter. Many apprehend that it could be catastrophic, since such developments would weaken the monsoon causing serious damage to Indian agriculture.
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