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International Cuisine Conference on Traditional Asian Diet
Panaji, Goa, September 2-5, 2007 - http://www.indologygoa.in
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Interview in Deccan Herald Sept 4, 2007
Arabian Sea could turn into chimney for nitrous oxide
If the present warming trend continues, it would have
far-reaching consequences on the ecosystem of the Arabian
Sea, says biological oceanographer Joaquim Goes.
The increasing meltdown of snow cover over the Himalayas and
the warming of the Eurasian landmass have triggered rapid and
profound changes in the Arabian Sea. Over the past seven
years, the western half of the Arabian Sea has witnessed
record increases in phytoplankton, which can cause oxygen
depletion below the surface waters. If the present warming
trend continues, it would have far-reaching consequences on
the ecosystem of the Arabian Sea, says biological
oceanographer Joaquim Goes.
A senior researcher at the Bigelow Laboratory for Ocean
Sciences, Maine, USA, Goa-born Goes is part of an
eight-member research team from the US, India and Oman on the
NASA-funded project "Climate Change and its impact on the
ecosystem of the Arabian Sea". On a cruise off the coast of
Goa, Goes spoke to Devika Sequeira of Deccan Herald about the
findings of the study so far. Excerpts:
Melting snow cover in the Himalayas is altering the ocean
food chain in the Arabian Sea. Can you explain the
correlation?
The Arabian Sea is a tropical ocean ecosystem, where
phytoplankton photosynthesis and growth is largely dependent
on the availability of adequate amount of nutrients. The
nutrients are made available by oceanographic processes,
which help churn the water column and transport nutrient rich
water from the deep ocean to the upper sunlight layers where
phytoplankton are usually found. In the Arabian Sea, this
mixing of nutrient-rich waters is driven primarily by the
monsoon winds, whose intensity is dependent on the pressure
gradient that develops between the Arabian Sea and the Indian
sub-continent.
The development of this pressure gradient is largely
regulated by the size of the snow caps over the
Himalayan-Tibetan Plateau. Over the past few years the snow
caps have been shrinking at a very alarming rate. There are
now clear indications that the glaciers on the
Himalayan-Tibetan mountain range are retreating at a very
rapid rate, as a result of global warming, which is altering
the pressure gradient between the sea and the land causing
the monsoon winds to intensify.
Your study shows that phytoplankton concentrations in the
western Arabian Sea have increased by over 350 per cent over
the past 7 years. Is there enough evidence to link this to
large fish kills off the coast of Oman?
Pollution, toxic algae or fish diseases are the common means
that can cause massive fish die-offs in coastal ecosystems.
At present we have no evidence to support the notion that any
of these factors are responsible for fish mortality off Oman.
On the other hand, the die-offs have consistently been
observed in conjunction with the appearance of oxygen-poor
seawater at the surface. Our hypothesis is that the dramatic
increase in phytoplankton biomass in the Arabian Sea,
witnessed over the past few years, is in excess of the amount
that can be eaten by higher organisms in the food chain.
Consequently, a large amount of organic matter, being
produced by phytoplankton in the sunlit layers, sinks out of
the water column into the deep unconsumed. Here bacterial
breakdown of these sinking material results in a rapid
reduction in oxygen to concentrations that will not allow
fish to survive.
The creation of nitrous oxide in the Arabian Sea could
exacerbate climate change, your study says. What would be its
effects on India?
Nitrous oxide is a green house gas that is over 400 times
more potent than carbon dioxide. If the biological
productivity in the Arabian Sea continues to increase, the
sea would start losing even more oxygen and its permanent
oxygen minimum zone could start to spread. The Arabian Sea is
one of the few oceans that have a permanent oxygen minimum
zone. This zone is favourable to the formation of nitrous
oxide (laughing gas). There is a possibility that the Arabian
Sea could become a sort of a chimney for this gas that could
exacerbate the warming trend and the melting of the Himalayan
snow caps.
Can you spell out the possible consequences of this?
Since the Himalayan snow caps are integral to the Indian
monsoon system, any further reduction in winter-time and
increase in ambient temperatures would make our monsoons even
more erratic. Each year floods and droughts will become more
commonplace. Without doubt, cyclone activity in the Arabian
Sea and the Bay of Bengal will intensify as the Indian
subcontinent continues to heat causing changes in land, sea
thermal and atmospheric pressure gradients. With rising sea
levels and increased storm surges during the monsoon, Mumbai
and Kolkata and other places along India's coastline will be
increasingly threatened by flooding. Even in Goa, we will
witness rapid erosion of our beaches.
Your research also tries to address the unusual storms in the
Arabian Sea. Is it a recent phenomena?
A couple of model runs lead us to believe that the warming
trend would result in increased storm activity and storm
surges. Gonu was one instance of a very uncommon cyclonic
storm to hit Oman. India should seriously start investing in
science that would improve our understanding of climate
change and its potential consequences on all aspects of our
life, especially the monsoon, which we heavily rely on for
agriculture and our drinking water needs. There will be no
easy solutions.
What is lacking in India in your field of research?
The competition for research funding in the US is very stiff,
which requires us to be constantly creative. In the US every
idea is greatly valued. The funding agencies do everything
within their means to help individual scientists' network and
build collaborations across disciplines. This is something
that needs to be done in India. If we are to understand the
effects of climate change on ocean ecosystems for instance,
atmospheric scientists need to work with oceanographers,
physicists and chemists need to talk to biologists and the
society needs to be made aware of new scientific findings
through robust outreach and education activities.
