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[Pawan Durani]

http://rinoorajesh.blogspot.com/2008/10/climate-change-and-civilizations.html
 Climate Change and
civilizations¡­<http://rinoorajesh.blogspot.com/2008/10/climate-change-and-civilizations.html>
In my previous post<http://rinoorajesh.blogspot.com/2008/09/global-warming-and-its-effects-on.html>on
the topic of global warming and its impact on planet's climate, I had
delved into the causes behind global warming and varying opinions of
different authority figures. This time, I would like to trace the effects of
climate change on the evolution of humanity.

I came across an interesting article by Dr Nachiketa Das ¨C where he
discusses the topic of climate change and its effect on river
Ganges<http://blogs.siliconindia.com/DrNachiketaDas/769p8m0i55859558>
.

He is of the opinion ¨C "*Global warming, now in 2008, is real, and upon us.
How will global warming affect the rivers in India; will they all dry up?
Can the holy Ganges, the river that has shaped and sustained Indian
civilization through the ages, who we Indians revere as the life-giving
mother, run dry! Many climate experts and environmentalists, in the last ten
years, have been making dire predictions of the Ganges becoming seasonal.
Some doomsayers have even gone to the extent of boldly predicting the river
to be ephemeral by the year 2035, which is barely a generation away! Is it
really possible that the Ganges will run dry by 2035! Is this calamity an
inevitability that should be accepted as fait accompli, or is there anything
we, the people of India, collectively can do to save the holy Mother Ganges
from extinction*".

The concerns are valid. The Ganges originates from Gangotri glacier, which
is one of the largest valley glaciers located in western Himalayas. 30.2 km
long and 0.5 to 2.5 km wide Gangotri lies recumbent at the altitudes between
4,120 and 7,000 m above sea level. The total area occupied by the glacier
complex (in 2001) that feeds Ganges, is 260 square km, which contains 40
cubic km of ice (in 1999). During a 60 year period between 1936 and 1996,
Gangotri has receded by as much as 1,147 m, 850 m of which happened during a
25 year period between 1971 and 1996. In a three year period between 1996
and 1999 Gangotri retreated by 76 m. When this result is contrasted with the
2,000 m retreat over the last 200 years, the significantly accelerated rate
of retreat has become obvious.

Also, Global warming does not mean uniform amount of warming at each and
every place on the globe. Although vast majority of the places on this earth
will become hotter due to global warming, however strange it may seem,
certain parts will in fact become cooler.

Why? Well, it has to with how the weather and heat transfer systems work on
our planet. Unlike the frozen wastes of Mars or lead melting surface of
Venus, our planet is blessed with a very complex, yet delicate ecosystem.

The Gulf Stream is a vast oceanic current that carries warm waters from the
tropics to the temperate regions of northern Europe and North America. This
ocean current originates in the Gulf of Mexico, flows past the east coast of
the USA and Newfoundland in Canada, and then crosses the Atlantic Ocean. It
then branches into two, with the northern stream moving to northern Europe.
The Gulf Stream is about 80 to 150 km wide and a 1,000 m deep river of sea
that transports 1.4 petawatts (1 petawatt is 1,000 million megawatts) of
heat, which is equivalent to almost 100 times the current energy demand of
the entire world. Around Cape Hatteras on the coast of North Carolina in the
US, the Gulf Stream transports water at the rate of 80 million cubic meter
per second, and is much bigger than any river system of the world; in fact
the combined release of all the waters from all the rivers flowing into the
Atlantic is only 0.6 million cubic meter per second.

The Gulf Stream has significant localized effects on the climate of the east
coast of Florida and Massachusetts in the US; and the west coast of Britain,
which is a good few degrees warmer than the east coast. The warming effect
of the Gulf Stream is most dramatic in the western islands of Scotland, so
much so that the small township of Plockton (latitude 57.33oN) that is
located east of the Isle of Skye, has a mild climate that allows
sub-tropical cabbage-palm-trees to grow. The local climate in Plockton in
the absence of the Gulf Stream would be freezing cold as latitudinal it lies
further north of Moscow (latitude 55.45oN) by almost two degrees.

Due to global warming, there is every possibility that the Gulf Stream may
change course or it may lose its strength. In fact in November 2004, it
completely stopped for full ten days, and there are reports saying that in
the last 50 years (since 1957) its deep return flow has weakened by as much
as 30%. Any change in the characteristics of the Gulf Stream, would cause
significant localized cooling in Scandinavia and Britain. At a time of
global warming, the western islands of Scotland will experience substantial
cooling.

The effects on human population and civilization can be imagined.

This, however, is the not the first time that climate change has affected
humanity on such a scale.

The river Sarasvati for example, is widely considered to have supported the
Harappan culture. Movement and ultimate decline of the Harappan culture are
often attributed to climate change and its ultimate effect on river
Sarasvati. Some Rigvedic verses (6.61.2-13) indicate that the Sarasvati
River originated in the hills or mountains (giri), where she "burst with her
strong waves the ridges of the hills (giri)". It is a matter of
interpretation whether this refers not merely to the Himalayan foothills
like the present-day Sarasvati (Sarsuti) river. The Sarasvati is described
as a river swollen (pinvam¨¡n¨¡) by other rivers (sindhubhih). Another
reference to the Sarasvati is in the geographical enumeration of the rivers
in the late Rigvedic Nadistuti sukta (10.75.5, this verse enumerates all
important rivers from the Ganges in the east up to the Indus in the west in
a strict geographical order), as "Ganga, Yamuna, Sarasvati, Shutudri", the
Sarasvati is placed between the Yamuna and the Sutlej, consistent with the
Ghaggar identification. It is clear, therefore, that even if she has
unmistakably lost much of her former prominence, Sarasvati remains
characterized as a river goddess throughout the Rigveda, being the home
river of the Puru and later on, the Kuru tribe.

While Sarasvati River might still be remembered, its influence on Indian
history cannot be discounted. Nor can its decline be overlooked.

However, climate change need not always be so bad for human culture. After
all, our present day humans ascended to our current position in evolutionary
terms due to ending of an ICE AGE.

Sahara desert, the largest one on our planet, used to be a very lush and
green place before the change in climate led to its present state and forced
a lot of human tribes into the valley of the Nile, leading up to its
fabulous civilization and myriad dynasties.

Sustenance played a crucial role in the founding of Egyptian civilization.
The Nile is an unending source of sustenance. The Nile made the land
surrounding it extremely fertile when it flooded or was inundated annually.
The Egyptians were able to cultivate wheat and crops around the Nile,
providing food for the general population. Also, the Nile's water attracted
game such as water buffalo; and after the Persians introduced them in the
7th century BC, camels. These animals could be killed for meat, or could be
captured, tamed and used for ploughing ¡ª or in the camels' case, travelling.
Water was vital to both people and livestock. The Nile was also a convenient
and efficient way of transportation for people and goods. The Nile played a
major role in politics and social life.

But at the end of the day, it was climate change which led to rise and fall
of these civilizations¡­.

So what are we worried about?

It's just that we humans are much more numerous now and spread of more area
of the planet than at any time in our history. So climate change this time,
turns out to be very inconvenient indeed and because it might lead to
decline of our current global civilization and ultimately bring misery to
untold billions, that we are so concerned.

We humans seem to be standing too much in the way of nature to be left
unscathed by the fury that will be unleashed by the current spell climate
change, arguably induced by our actions only¡­