The
geological perspective of climate change
By Malini
Shankar
Dr. M.N. Rajeevan the Director of
Indian Institute of Tropical Meteorology (http://www.tropmet.res.in/) in Pune
tells this writer exclusively by email “The Chennai flood was caused due to
continuous rainfall activity concentrated over coastal Tamil Nadu, around
Chennai between 28th Nov – and 3rd December.
“However, rainfall during 01-02
December at Chennai (around 35 Cm) was an extraordinary event; Recent studies
suggest that such heavy rainfall spells are increasing and may increase in
future due to global warming. The Chennai flood is caused due to above normal
rainfall activity during the northeast monsoon season (October to December).
The above normal rainfall during the season was expected as this year is an El
Nino year and we can expect above normal NE Monsoon rainfall during El Nino
periods” adds Dr. Rajeevan.
El Nino or climate change, the third
dimension of the Chennai floods is encroachment of water bodies (courtesy the
political class) that act as natural drainage in coastal ecosystems. “T Nagar
is an affluent residential suburb in Chennai today but it is built on ponds
that were clogged by developers and builders between 1978 and 1981”.
“After the Mumbai flood of July 2005
a committee of which I was a member, recommended that water weirs have to be redesigned
and constructed to drain high tide water that lashes the city. But this water continues
to remain in the city’s cemented environment; - clogged and unable to discharge
into the sea; no action seems to have been taken to mitigate such future
disasters” said Dr. Arun Bapat noted geologist, speaking exclusively to this
writer.
El Nino is a term that refers to the
reversal of the normally anticlockwise cold Humboldt Current that hugs the
Chilean coast in the South Pacific Ocean and coursing instead in a clockwise
motion, thus reversing seasons corresponding to a latitude-longitude
calibration right across the whole world.
El Nino is notorious for exacerbating
weather systems bringing unseasonal weather almost around the whole world and
in places where there is no unseasonal weather, the weather heaves gargantuan
impacts. Thorough documentation is the first step towards preparedness.
El Nino exacerbates all
hydrometeorological calamities - Avalanches, Blizzards, Cloudbursts, Coastal
Incursion, Cyclones, Droughts, Desertification, (differential impact of) El
Niño Southern Oscillation, Epidemics, Floods, Flash Floods, Famine, Forest
Fires, Fog, Hailstorm Landslides, Mudslides, sand storm, Sea surge, Storms,
squalls, thunderstorms and urban floods. Tsunamis triggered by ice berg melt
and seamount explosions may also construe hydrometeorological disasters by
definition atleast. Overground peat emissions in Indonesia spawn forest fires;
and fog in Indonesia being exacerbated by El Nino events of 1998 and 2015 has
been documented.
Understanding geological phenomena
like El Nino helps documentation so we know better in the future. Sea level
rise corresponds to the sinking of riparian deltas thanks to the deposition of
silt say the purists.
Quantifying the Subterranean peat
emissions of methane from deep underground by source will strengthen the case
for reduction in emissions. The melting permafrost formed in Siberia 11,000
years ago is developing massive sinkholes with one being recorded as 70 metres
deep and 600 metres in diametre. Hydrometeorological disasters will
have increasingly debilitating impact on vulnerable communities and Island
States in the decades ahead if emission targets are not met.
That the geological perspective of
climate change is significant (http://ete.cet.edu/gcc/?/volcanoes_teacherpage/) was also supported
by a study of the Earth and Environment, University of Leeds which quantified
the emissions from Iceland’s Bardarbunga volcanic eruption of summer 2014 @
120,000 tons of sulphur dioxide gas per day at the onset of its eruption
completely outdoing the industrial emissions in Europe. According to the NASA website on volcanoes’ connection to Climate change ((http://ete.cet.edu/gcc/?/volcanoes_teacherpage/)
this is because sulphur dioxide is cooling in comparison to CO and CO2
emissions that obtain from industrialisation and vehicular emissions.
According to a new study on the
subject -- published in the Journal of Geophysical Research, Atmospheres http://onlinelibrary.wiley.com/doi/10.1002/2015JD023638/full -- the
volcano's toxic emissions bested the average amount of sulphur dioxide produced
by European industry, by a large margin.
“The eruption discharged lava at a
rate of more than 200 cubic metres per second. In the study, we were concerned
with the quantity of sulphur dioxide emissions, with numbers that are equally
astonishing: In the beginning, the eruption emitted about eight times more
sulphur dioxide per day than is emitted from all man-made sources in Europe per
day” Dr Anja Schmidt School of Earth and Environment, University of Leeds said
in a press release (http://www.ed.ac.uk/news/2015/volcano-230915). Its
significance lies in emphasising the natural, benign sources of global cooling like
volcanic emissions.
So does it mean that man-made
emissions can be overwhelmed by volcanic emissions? Climate scientists aver and
with good reason that anthropocentric emissions of CO2 is hundred
times more than volcanic emissions on a year to year basis. It is a thin line
of distinction that differentiates the emissions from steam and water vapour in
the atmosphere. While volcanic emissions of SO2 cools the
atmosphere, <1% of CO2 from volcanic emissions warm the
atmosphere according to a NASA website article (http://ete.cet.edu/gcc/?/volcanoes_teafrpage/)
There are many other examples of volcanological
perspective of climate change. Lake Toba’s super volcanic eruption 74000 years
ago robbed the earth of sun rays triggering the Ice Age.
http://volcano.si.edu/Photos/full/119067.jpg
Krakatau super volcanic eruption in
the Java Straits in August 1883 triggered a short term climate change globally,
inducing spectacular sunsets on the Chesapeake Bay near Washington DC on the
East Coast of the United States for months after the super volcanic eruption of
1883.
In Bengal in India the Sun could not
be sighted for a decade. “But a decade after the Krakatau super volcanic
explosion”, - seismologists – like Dr. Arun Bapat allude to the transient
nature of short term climate change – “wherever the ash of Krakatau had fallen,
the agricultural lands became very fertile for six to eight years following
the volcanic eruption”.
The Tambora super volcanic eruption
in Sumbawa in Indonesia triggered the Year Without a Summer in Canadian Eastern
Sea Board in 1815 - 16. It took a decade for the global climate to stabilise
after Tambora’s eruption.
Mount Pinatubo’s eruption in the
Philippines in October 1991 cooled the planet by a significant 10 C, clearly establishing the link
between global weather and volcanism. “During the 1900s there were three large
eruptions that caused the entire planet to cool down by as much as 1°C.
Volcanic cooling persist for only 2 to 3 years because the aerosols ultimately
fall out of the stratosphere and enter the lower atmosphere where rain and wind
quickly disperse them”. (http://ete.cet.edu/gcc/?/volcanoes_teacherpage/)
Climate scientists worry at the rapid
pace of glacial retreats triggered by fossil fuel emissions and anthropocentric
triggers like vehicular emissions. It only underscores the need for planned
development - a challenge to the political elites in the current World Order. But
geologists are sceptical of glacial retreat being triggered by anthropocentric
emissions.
“Last Glacial Maximum Period is also a matter
for study. It has been observed that most of the glaciation – there is evidence
to suggest that major glacial advancement happened 50 – 55000 years ago, but it
is still being worked out, but after that period there have been 3 – 4 periods
of glaciations and de-glaciation. Glacial advancement and recession is a
climate change cycle. It is not happening for the first time, we have those
records. There is a geological cycle to it…” says Professor Rameshwar Bali
Associate Professor of Geology at the Centre of Advanced Studies in Geology,
Lucknow University.
“…For us in the Indian subcontinent
global warming is not as bad as global cooling because then the monsoons and
economy will be severely affected. Monsoons happen because of summer warming
but if the summer temperatures cool, monsoons are affected, impairing our
economy and the whole cycle of seasons in Asia. So global cooling is more
dangerous to tropical countries as the entire economic cycle will be affected
by global cooling and inadequate monsoons. Entire Indian Ocean rim countries
will be affected” says Professor Bali during a discussion with this writer for my
book research: “Preparing for the Day After” (https://play.google.com/store/books/details?id=EbzkBQAAQBAJ)
Retired Dean of Institute of Socio
Economic Change (http://www.isec.ac.in/) Professor
R. S. Deshpande says “modelling micro climate for long period average is
difficult given that micro climate itself is affected by terrain, waterscape, landscape,
humidity, precipitation (rainfall / snowfall) wind speeds etc. Lat long
calibration of long term global climate is correspondingly diverse and challenging. Climate
change has over the millennia shaped climate change adaptation - change in
cropping patterns and consumption of agricultural produce”.
The earth’s axis varies between 220
and 24.50 according to the Milankovitch Cycle http://earthobservatory.nasa.gov/Features/Milankovitch/). Milutin Milankovitch, a prisoner of Stalinist
Russia in Siberia during the 2nd World War hypothesized that the speed of the
earth’s revolution on its elliptical orbit is altered by the velocity of the
earth’s rotation on its axis once in about 41000 years triggering a change in
the angle of the earth’s tilt from an elliptical to circular orbit… thus making
climate change inevitable.
This change in the tilt of its axis
alters the amount of Sun’s radiation falling on earth – accounts for change in
seasons drastically in the middle and higher latitudes (Our Changing Climate
Fall 1994 – Volume 4 http://www.atmos.washington.edu/~dennis/RTN4.pdf) by Dennis
Hartmann, University of Washington. Such changes inevitably have impact on
zoological and biological diversity.
Zoological perspective of climate change and its impact in South Asia
Speaking exclusively to this writer, Professor R. Sukumar of the Centre
for Ecological Sciences at the premier Indian Institute of Science in
Bangalore, said “Climate change is an ongoing phenomenon over the past millions
of years. Between the Pleistocene Era
(around 2.6 million years ago to about 10,000 years ago) which marks the
beginning of the Holocene era there were about 25 periods of glaciation and
inter glaciation with warmer climes lasting shorter periods.
The Last Glacial Maximum being the coldest period of glaciation occurred
about 20,000 years ago. The cooling trend would have started much before that.
Cold periods were also arid periods as rainfall declined. During such cold
periods the tropical moist forests would have shrunk or contracted to small
areas. … These places are referred to as Pleistocene Refugia. In
India only two such shrunk places were there … in the extreme southwest and
northeast of the subcontinent. Elephants were confined to these refugia
during extremely cold periods.
The rest of India was arid scrub land or savanna ecosystems supporting
fauna such as ostriches that can thrive in such ecosystems … (incidentally,
giraffes were found in the subcontinent during the early Pleistocene while
tigers entered the subcontinent from the Far East only after the climate warmed
up after the Last Glacial Maximum - … somewhere between 20000 to 10000 years
ago). This global warming would have facilitated an expansion of tropical moist
forests on account of strengthening of the monsoon, and thus these more
productive ranges of habitats would have supported a somewhat different faunal
diversity.”
Mammals like apes, antelopes, bats, cheetahs, wild dogs, elephants, rhinos, wild dogs, hippos, giraffe, birds like ostriches, reptiles like snakes, crocodiles, etc have
all been documented by studies of Kurnool Caves by G.L. Badam et al (http://www.rhinoresourcecenter.com/pdf_files/127/1272188698.pdf). Interestingly Asian Elephants started moving
out of Pleistocene Refugia in extreme southwest (Southern Western Ghats) only
when the climate became warmer supporting tropical broad leaved forests.
It seems like the fauna found in Africa today were all once endemic to
the Indian subcontinent too, but have gone locally extinct … as a
geomorphological adaptation of climate change.
What is not so easy to comprehend is
the cyclical pattern of El Nino. The pattern of the notorious El Nino cycles
desperately needs to be studied accurately, if only to be prepared for the
catastrophic impact the geological cycle has on agriculture, fishing, food
security and global economy. Given its varying cycles and its differential
impacts on micro climate right across the world, modelling El Nino triggered
extreme weather globally has become the greatest challenge of our times.
Could it be that volcanic eruptions
in the South Pacific Ocean plausibly determine the course of currents
accounting for reversing the normally anticlockwise course of the Humboldt
Current on the west coast of Chile in the South Pacific? It thus alters the
normal course of hydrometeorological cycles right across the world offsetting
the hydrology and currents in each Latitude and Longitude… accounting for the
variations in agro meteorology, fisheries, shipping, and global economy.
The role of seamounts in the South
Pacific Ocean in warming the waters of the South Pacific Ocean and also in reversing the normally anti
clockwise cold Humboldt Current to a clockwise course / rotation demands
credible attention too (http://wattsupwiththat.com/2012/02/15/do-underwater-volcanoes-have-an-effect-on-enso/).
It is only when we understand the
geological perspective of climate change can we do accurate justice to mitigation.
© Pictures courtesy Global Volcanism Programme of the Smithsonian Institutions, and Text by
Malini Shankar
