Danger Signals
Professor Brahmachari of Calcutta University draws our
attention to the causes and perilous effects of global
warming in this article.
A team of American tourists to the North Pole was surprised
in 2000 to find a freshwater lake 1.5 km right at 90 degree
N. Experts opined that such a situation prevailed 50
million years ago also. The ice in the polar region now
covers six per cent less area and is 40 per cent thinner
than twenty-five years ago.
Hurricanes Katrina and Rita could attain the severity that
they did due to warm temperatures of the Florida Bay. Dr.
Webster of Georgia Institute of Technology has found that
ocean temperatures above 26 degrees C might increase the
number and severity of storms. On analysis of surface
temperatures obtained from satellite data of six ocean
basins he has observed that the average ocean surface
temperature has risen by 0.5 degree C all over the globe.
But he has found that only the North Atlantic has suffered
the most. Although the total number of storms has remained
almost the same over the years, their severity has gone up.
Another spectacular observation that he made was although
in the South West Pacific the rise in ocean surface
temperature has not been considerable; category five
hurricanes that are the severest have been more frequent.
In another paper in the same journal Greg Holland and Judy
Curry of GIT have studied the frequency and intensities of
hurricanes for the last 35 years. Number of category one,
two and three storms has reduced and that of four and five
have gone up.
In another paper in Nature in August 2005 Kerry Emanuel of
Massachusetts Institute of Technology scanned 4800
hurricanes for last 56 years in the North Atlantic. His
findings are also similar in that though the frequency of
hurricanes remains the same, their power increased. Also
North Atlantic has seen an increase in number of hurricanes
in the last 10 years whereas North Pacific has seen a
corresponding reduction. Hurricanes that strike the land
attract the publicity for the destruction they cause to
human lives and wealth. There are many hurricanes that
originate and perish in the oceans it without attracting
much of an attention since they do no damage to mankind.
The city of New Orleans alone suffered a loss of 100
billion dollars and 10,000 lives due to Katrina alone
according to a rough estimate.
Violent hurricanes are forerunners of climatic changes.
Kevin Trenberth of the National Centre for Atmospheric
Research (NCAR) of Colorado is of the opinion that climates
are definitely changing and humans are partly responsible
for it. More intense storms and heavy rainfalls indicate
that the changes would be colossal, the worst of which is
yet to come.
The writer goes on to explain the physics and chemistry of
Global warming. Almost half of the excess heat is
transferred through water by ocean currents and the rest by
storm. Any change in temperature differential between the
tropics and Polar Regions changes the climate to that
extent.
Emission of green house gases has reached 7.2 billion
metric tons in 2000. These gases are mostly emitted by 34
industrialized nations. By the end of 21st century
temperature of earth may rise by 3.5 to 5 degree C
enhancing water vapour content in atmosphere fuelling
violent storms. Katrina alone contributed 12-inch rainfall
at New Orleans.
Warmer waters (3 degree C higher than normal) of the Gulf
of Mexico fuelled both Katrina and Rita last year within a
span of three weeks. Nam walker, director of Louisiana
State University’s earth scan laboratory says that a
hurricane passing over a U-shaped stream of warm water in
the gulf might have gathered deadly energy before striking
the coast line.
There are skeptics who underplay all the above findings and
say that the storms are not necessarily more furious, they
merely target thickly populated coastal areas. The density
of population in the coastal areas has become 75% higher in
Florida alone and that has aggravated the problems.
Whatever may be the arguments, the existence of the
problem of global warming cannot be wished away. At this
rate the life support system in the colder regions is
breaking down compelling the birds and amphibians to move
further in search of colder ambient. If temperatures
continue to soar at the present rate the polar ice caps
would vanish by 2080 raising ocean levels and completely
submerging low lying areas.
India has to tackle the dual problems of weaker monsoons
and loss of agricultural coastal lands due to rising sea
levels.