Download Vijaya Singh

Global Warming Has Its Compensations
Vijaya Singh
Formerly General Manager, Central Railway &
Former Managing Director, Tata Projects Ltd.
Prologue
The Author has written on a vast range of
subjects including construction
technology, engineering consultancy,
privatization, environment, etc. This
Paper, ‘Global Warming Has Its
Compensations’, brings out the positive
aspects of global warming.
The Author argues that Global Warming
is a reality and it is also accepted that it
is the result of a combination of natural
causes and human activity, but which one
is predominant is debatable. Global
warming will affect the environment, and
the magnitude of this effect will depend
upon the extent of increase in temperature.
The estimated increase in temperature by
the end of the 21st Century varies from
1.4oC to 5.8oC according to the IPCC
Report. The range, however, is even wider
in models adopted by different scientific
institutions. This creates doubts about the
reliability of these projections and the
consequent environmental changes.
A scary picture is being drawn of what
may happen in future. Water level of
oceans will rise submerging vast areas of
land, resulting in migration of millions of
people. There would be floods and
droughts; a sharp decline in food
production, and millions could die of
starvation. Some of the species, which
require cold climate for survival would
become extinct and damage will be
caused to marine life, coral reefs, etc.
The Author brings out that the positive
effects of global warming, such as faster
and healthier growth of plants and increase
in production of food grains due to
enrichment of atmosphere with CO2,
increase in the availability of fresh water
due to increase in rainfall, improved
availability of sea food and many others,
are not getting highlighted. The purpose
of this Paper is to present a balanced view
of the effects of climate change. The
planners should also keep in view the
uncertainty about the extent of climate
change and its causes.
Like the Author says, nature has its own
self-correction mechanism for countering
the adverse effects of human activity, it is
hoped that this mechanism, together with
the corrective global measures being
taken, would bring down the adverse
effects of global warming. Let us hope that
this will bring a happy ending to the 21st
century.
- Editor
Introduction
The global temperature has risen by about 0.74oC during the last 100 years
and has been rising at an accelerated rate of 0.25oC per decade during the recent
RITES Journal
16.1
July 2009
16.2
Global Warming Has Its Compensations
years. The projections of the increase in temperature till the end of the 21st Century
range from 1.4oC to 5.8oC according to the IPCC report while according to models
prepared by various scientific organizations, the range is even wider .The Centre for
Climate Systems Research (CCSR) & National Institute of Environmental Studies
(NIES) have projected an increase of 7.0oC over land and 3.8oC in the oceans from
1890 to 2100. The National Center for Atmospheric Research (CSM Model 20002099) has projected an increase in land temperature of 2.7oC and in the oceans of
2.0oC. Other institutions have projected figures between these two extremes. The
differences arise due to the different assumptions made for the emission of greenhouse gases during the period under consideration, and social and economic factors
relevant to climate change in developed and developing countries, the relationship
between CO2 emissions and climate change, as also the effect of other variables
which have a bearing on the climate change.
The Intergovernmental Panel on Climate Change (IPCC) has attributed the
rise in global temperature primarily due to human activity. However, there are dissenting
voices according to which the changes may be primarily on account of enormous
natural forces which are at work, each one having a different and variable periodicity,
as a result of which the effect of each is difficult to isolate or predict.
The IPCC has drawn a grim picture of the devastation the climate change
may bring about, which includes rise in the water level in the oceans as a result of
melting of ice in the glaciers and in the polar region. The expansion due to rise in
temperature, which would result in submergence of many coastal cities and low lying
coastal areas and migration of millions of people from these areas. They have also
predicted stormy weather, floods and droughts, fall in food production, damage to
marine life, extinction of many species and spread of tropical diseases in the form of
epidemics. They have recommended various measures to avoid this catastrophe, the
most important of which is to control the emission of green-house gases. Carbon
dioxide (CO2) is the most important green-house gas and the important sources of
these emissions are the thermal powerhouses and other industries using coal and
hydrocarbons as fuel, and automobiles. The second important green-house gas is
methane, the emission sources of which are the rice fields, marshes and decaying
organic matter.
Scientists have not been able to establish a quantitative cause and effect
relationship between the concentration of CO2 in the atmosphere and the rise in
global temperature. Reliable observations of the two variables from satellites are
available only for the last thirty years and the observed figures are a combination of
the effects of natural forces and human activity. It is difficult to predict the concentration
of CO2 as a result of human activity, as it has been found that all the CO2 emitted does
not remain in the atmosphere and about 50 % of it is eliminated by the nature’s selfcorrecting mechanism comprising of the forest cover and the oceans which act as
‘sinks’ for CO2.
Vijaya Singh
16.3
As regards the consequences of global warming, its negative effects have
received a lot of emphasis, while the positive effects have not been adequately projected.
It is well known that CO2 is the staple food of plants and its higher concentration in the
atmosphere promotes their growth .This will lead to healthier forests and increase in
farm production. The movement of the snow line to a higher level will result in greening
of hill slopes which used to remain covered with ice throughout the year and, similarly,
the land exposed due to melting of ice will add to the forest cover. It has been stated
that food production will go down due to the rise in temperature. In fact, warm and wet
weather, together with higher concentration of CO2 in the atmosphere, are healthy for
the growth of plants. Some of the areas in Siberia and Canada, which are too cold at
present to permit agriculture, will become productive farming areas with global warming.
Favorable conditions may also lead to improved availability of sea food. Higher
temperatures will lead to higher rainfall and improved availability of fresh water for
irrigation and domestic consumption. Loss of storage in the form of ice caps on the
mountains could be made up by constructing high dams in the mountains, low bunds
and contour-bunding in undulating areas and water harvesting in the plains .The increase
in the potential of clean hydroelectricity will be an added advantage.
The purpose of this Paper is to present a balanced view of the effects of
global warming on the life on earth. Some of the important developments which are
likely to occur as a consequence of global warming are discussed in this Article.
Availability of Fresh Water
Increase in global temperature will result in greater evaporation from the oceans,
formation of more clouds and increase in rainfall. This would improve the availability of
fresh water and will provide relief from the problem of growing shortage of fresh water,
which has been causing concern during the recent years. This water will have to be
stored and storage capacity will have to be created in order to ensure that this fresh
water does not flow back into the sea. A portion of the natural storage capacity in the
form of ice cover in the mountains will be lost as a result of global warming and the
storage capacity to be created will have to take this fact into account.
The rainfall in the mountains will have to be stored by constructing high
dams, while in undulating areas, low dams will have to be constructed and soil erosion
will have to be prevented by contour- bunding. In the plains, water harvesting will have
to be done in urban areas and also in the country-side on an extensive scale in order
to recharge the under ground storage, which is a source of water supply throughout
the years. All these methods will have to be adopted in order to maximise the storage
capacity and the controversy about one method being superior to the other is futile,
as these are not interchangeable.
The stored water can be released during dry months to meet the requirements
of irrigation, human consumption and to flush out the polluted water coming into the
rivers from all directions, which carries with it the excreta of wild animals, decaying
16.4
Global Warming Has Its Compensations
vegetation and other impurities, apart from industrial waste and sewage from human
habitations. Continuous flow of fresh water throughout the year will prevent ingress of
saline water from the oceans into the rivers and will also prevent increase of salinity in
the subsoil water.
It has been stated that while the areas which are wet will receive more rainfall
due to global warming, the dry areas will become drier. This does not appear to be
logical as most of the surface of the earth is covered by oceans and higher temperature
will result in the formation of more water vapour. It is expected that increase of 1oC in
the average temperature will result in about 7% increase in the concentration of water
vapour in the atmosphere, which will promote the formation of morning dew, and this
applies equally to dry areas. There is also no reason why the rainfall should reduce in
dry areas on account of global warming.
There have been acute drought conditions in Southwest Australia for the last
seven years and also in Arizona in USA for many years and they have been attributed
to global warming by some scientists. In this context, the following excerpt from the
article titled “Outlook Extreme” by Elizabeth Kolbert, published in the April 2009
Issue of the National Geographic is relevant :
“It is now believed that Akkad (Pre-Babylon) collapse was caused by a
devastating drought. Other civilizations whose demise has recently been linked
to shift in rainfall include the Old Kingdom of Egypt, which fell right around the
same time as Akkad, the Timanacu civilization which thrived near lake Titicaca in
the Andes for more than a millennium before its fields were abandoned around AD
1100, and the classic Maya civilization, which collapsed at the height of its
development around AD 1800. The rainfall changes which devastated these
civilizations long predate industrialization; they occurred by naturally occurring
climate shifts whose causes remain uncertain.”
Increase in the Potential for Hydroelectricity and Wind Power
Storage of water in high dams will have an additional advantage of creating
potential for the generation of hydroelectricity. This is a renewable source of energy,
which causes no pollution and is eco-friendly. It is also the cheapest source of energy
and it is possible to adjust the generation of power to suite the requirement within a
short time, which makes it suitable for meeting the peaking requirement in a major
power supply system.
Reservoirs are also the most effective device for controlling floods and to
check the extensive damage caused by them. This is important in view of the anticipated
increase in flood intensity as a result of increase in rainfall on account of global
warming. It is true that the reservoirs behind the high dams submerge the forest areas
in the valley, but this is compensated manifold by the greening of the area irrigated by
the reservoir.
Vijaya Singh
16.5
It is expected that the global warming will lead to higher pressure differentials
in different parts of the globe, which would result in higher wind velocity and this
enhanced wind energy can be harnessed by converting it into mechanical energy or
electricity. Wind power is a clean and renewable source of energy and is also cheaper
in the long run, although its initial capital cost is high.
Global warming may also result in higher intensity of storms and tornadoes,
and action will have to be taken to protect the population from the damage which can
be caused by them.
Greening of the Earth
Warm and wet climate is favorable for the growth of all forms of life and
tropical forests are the densest and are full of wild life. Global warming accompanied
by increase in rainfall will promote the growth of plants and all other species which
depend upon plants for their survival. Added to this will be the abundance of CO2 in the
atmosphere which is the staple food of plants and would lead to their healthier and
faster growth and improved yield of flowers and seeds. This has been proved by trials
under controlled conditions.
Even in temperate zones there will be improvement in the growth of plants
and increase in rainfall will help in the greening of arid areas. Greening of the SubSahara in recent years has been attributed to higher concentration of CO2 and water
vapour in the atmosphere. Even in Rajasthan, the desert area has shrunk, which can
be attributed partly to an increase in rainfall in successive years and partly to other
factors such as reduced grazing and extension of irrigation facilities. This trend may
get accelerated as a result of global warming.
Areas in higher latitudes which are too cold for survival of plants will also
become suitable for supporting plant life and other forms of life dependant on plants.
The forest cover in Russia and Canada may increase considerably depending upon
the extent of global warming.
Glaciers have been receding and will continue to do so as a result of global
warming and the snow line will move to a higher level. Large areas of hill slopes, which
remain covered with snow throughout the year, will get exposed and will gradually get
covered with coniferous trees.
It is true that the living space available to species requiring cold climate,
such as polar bear, pelican and whales, will shrink but there will be corresponding
increase in the living space for species requiring warm climate such as the tiger,
which are struggling for survival due to shortage of living space.
It is also true that favorable conditions for survival of all forms of life will also
be suitable for carriers of diseases like malaria, cholera and plague but medical
science has succeeded in eradicating them in areas in which they were endemic and
16.6
Global Warming Has Its Compensations
the fear that there will be a resurgence of these epidemics as a result of global
warming, is not justified.
It will be seen from the above discussion that global warming will not have an
overall unfavorable effect on global environment and adverse effects in some areas will
be compensated by gains in other areas.
Boost to Agriculture
Fear has been expressed by eminent scientists that there would be a drastic
reduction in food production as a result of global warming as yields will come down
and some areas may become unsuitable for crops which are being grown there at
present. The fear is not justified and in fact there may be an increase in global food
production as a result of climate change.
It has been established under controlled conditions that there is an
improvement in plant growth and yield of food grains as a result of the enrichment of
the atmosphere with higher concentration of CO2. It is also known that all the important
food crops are grown in a wide range of climatic conditions and it has been possible
to obtain high yields in all these conditions by providing suitable inputs. Even the area
available for food production will expand as vast areas, which were too cold to support
agriculture, will become available for growing crops and areas, which could have only
one crop during the short summer, will be able to grow two crops as a result of
extension of the summer season. Siberia, Canada, Northern areas of Europe and
USA will be the main beneficiaries. It is reported that Greenland has already started
growing green vegetables as a result of melting of ice and exposure of land due to an
increase in temperature in recent years.
The conclusion that there will be no loss in global food production as a result
of climate change is supported by studies, independently, made by different
organizations. An American study has come to the conclusion that there will be
regional variations in the yield, with gains in the North and losses in the South. The
Pew Report adopted the consensus view that the impact of climate change on food
production will be very moderate for the world as a whole, but various regions may
suffer impacts, particularly if they are fringe agricultural areas at present. The Mink
Study concluded that taking into account CO2 enrichment, there will be a marginal
drop in the production of corn, sorghum and Soya bean while there will be 8% increase
in the production of wheat. All these studies do not take into account the capability of
modern genetic engineering to produce new strains, which can give improved yields
in changed climatic conditions.
In the following paragraphs, detailed data is presented on three important
food crops, viz., wheat, rice and maize (corn), on which detailed studies have been
made to determine the effect of climate change on yield in different areas.
Vijaya Singh
16.7
Wheat
Wheat is the most important food crop of the world with an annual production
of about 600 million tons; it leads all other crops including rice, maize and potato. It is
cultivated over 240 million hectares under widely varying climatic conditions.
Although the crop is most successful between the latitudes 30oN and 60oN,
and 27 S and 40oS, wheat can be grown beyond these areas, from within the Arctic
Circle to higher altitudes near the Equator. The crop is grown from sea level to an
elevation of more than 3000 m above sea level and even at 4570 m above sea level, in
Tibet.
o
Wheat cultivation is done in the warm climate of the Indo-Gangetic plain and
in Egypt and in the cold climate of Europe, Russia, Canada, USA, and in a wide
range of climatic conditions in China. Though the optimum temperature for the growth
of wheat plant is about 25oC, the minimum and maximum temperatures range from
3oC to 32oC. Wheat crop can also be cultivated successfully in a wide range of moisture
conditions with annual rainfall ranging from 250mm to 1750mm.
Wheat has been cultivated for almost 8000 years in different parts of the
world and wide ranges of strains are available, which are suitable for different climatic
conditions. With the latest developments in technology, new high yielding hybrid
varieties have been developed to suit the climatic conditions prevailing in a particular
area and new strains can be developed if the climate change so warrants.
The pattern of cultivation varies under different climatic conditions. In the
warm Indo-Gangetic plains, wheat is sown during the autumn, it grows during the
winter months, winter being mild in that region, and is harvested during the spring.
In regions having cold climate wheat is cultivated either as a winter crop or as
a summer crop. For the winter crop, sowing is done during the autumn. The small
plants remain dormant during winter months when the temperature is in the range of
3oC to 4oC and start growing again during the spring. Its harvesting is done during the
summer. The summer crop is sown during the spring and it grows and matures in
summer.
Yields vary widely from country to country and within the country, depending
upon the quality of seeds and inputs like irrigation and nutrients. Table 1 shows the
average yields per hectare for some of the wheat producing countries.
Table 1
Country
France
Germany
UK
Russia
China
India
Egypt
USA
Canada
Yield in Tons per Hectare
6.23
6.50
7.78
1.71
3.91
2.62
6.15
2.97
2.25
16.8
Global Warming Has Its Compensations
This shows the potential which exists for increasing wheat production. In
China and Russia it should be possible to match the production levels of European
countries having similar climatic conditions, and in India it should be possible to
match the levels in Egypt, which also has a warm climate.
Minor changes in temperature of a few degrees keep on taking place from
year to year and the plants are able to adapt to them without any significant change
in yield. If the changes are of a permanent nature then one can take care of them by
minor adaptation like early sowing so that sufficient period is available for growth of
the plant. If the rise in temperature is of an even higher magnitude, one can select the
seed variety suitable for the changed climatic conditions, and the areas which are on
the margin may switch over to paddy cultivation or some other crop which is more
suitable for the changed climatic conditions.
Further, the rise in temperature will open up areas in Europe, Canada and
Russia, which remain snow-bound and are not suitable for wheat cultivation at present.
Even in moderately cold areas, the yields are expected to improve as a result of rise
in temperature, which would more than compensate the loss, if any, in warm areas.
In addition to the above, is the factor of enrichment of the atmosphere with
CO2 .It has been established under controlled conditions that the yield of wheat would
improve by about 16% with increase in CO2 concentration from the present level of
367 ppm to 550 ppm and by extrapolation, it is expected to increase by 28% if the
concentration of CO2 increases to 700 ppm. The benefit is even greater if the increase
in the concentration of CO2 is accompanied by rise in temperature, which is likely to
happen as a result of global warming.
IPCC Assessment Report-3, Climate Change 2001, has come to the
conclusion that the overall effect of climate change on wheat production, taking into
account the enrichment of atmosphere with CO2, will be positive.
Rice
Rice is the second most important food crop. The global production of paddy
was 650 million tons in 2007, out of which 590 million tons was in Asia. The global
production of milled rice was 429 million tons.
Rice is a tropical and sub-tropical plant and requires fairly high temperatures
ranging from 20oC to 40oC for its growth, the optimum temperature being 30oC during
day time and 20oC during night time. The period of sunshine and length of the day are
also important. The crop requires a lot of water and areas having heavy rainfall are
most suitable for its cultivation. The most favorable conditions exist in China, India,
Indonesia, Bangladesh and Myanmar but rice is grown even in a cold country like
Japan, in small quantities in European countries and in the extreme cold of Oceania.
Rice is also grown in dry countries like Egypt and Australia.
Vijaya Singh
16.9
Table 2 gives the production and yield of paddy in some of the rice producing
countries for the year 2007.
Table 2
Country
Production in million tons
Yield in tons/hectare
650.2
590.2
185.5
141.1
57.0
43.5
32.6
11.0
9.0
6.7
3.5
0.2
4.15
4.21
6.35
3.21
4.69
3.88
3.98
6.54
8.05
9.97
5.71
6.72
Global
Asia
China
India
Indonesia
Bangladesh
Myanmar
Japan
USA
Egypt
Europe
Oceania
It will be noted from the above table that high yields have been obtained in
countries having divergent climatic conditions. In large countries like India and China
yields are not very contrary in different regions. In India, rice is cultivated right from
Kanya Kumari, the Southern tip of the country to Kashmir Valley, Uttrakhand and
Himachal Pradesh in the North. The Doon Valley in the Himalayan region is the home
of the world famous Basmati rice.
In China also, rice cultivation is done right from 18oN to 53oN latitudes, having
a wide range of temperature variation. All these areas have one thing in common –
they have abundant monsoon rains. Table 3 gives the statistics of different Rice Zones
of China. Although the figures are for the year 1989, and production and yields have
gone up considerably after that, the figures do bring out the relative position of
production and yield in different Regions.
Table 3
Rice Production Statistics in Ecological Zones of China
Rice
Ecological
Zone
South China,
double rice
cropping
region
Proportion of
Rice Area
(%)
17.7
Proportion
of Rice
production
(%)
Accumulated Precipitation
annual
(mm)
temperature
(>10oC)
Cropping
System
15.7
5800-9300
Three
maturing,
73.5% of
double rice
1200-2500
Contd.
16.10
Central
China,
double and
single
rice cropping
region
Global Warming Has Its Compensations
68.1
69.9
4500-6500
800-2000
Two or three
maturing,40%
of double rice
and 60% of
single rice.
Southwestern
plateau region of
single and double
rice cropping.
7.8
7.6
2900-3000
800-1400
Two maturing.
93% of single
rice and 7% of
double rice.
North China,
single rice
cropping region.
3.3
3.4
4000-5000
580-1000
One or two
maturing,
single rice.
Northeast
China, early
maturing and
single rice
cropping region.
2.6
2.9
2000-3700
350-1100
One maturing,
single rice.
Northwest
China, single rice
cropping region
in dry areas.
0.5
0.5
2000-4250
50-600
One maturing,
single rice.
The ratio of the figures in columns 2 and 3 is fairly constant, which shows
that almost similar yields are being obtained in zones having widely different temperature
and precipitation conditions.
It is clear from the above discussion that there is an ample scope for adaptation
of rice cultivation to different climatic conditions and a slight increase in global
temperature is not going to have any significant effect on production of rice. Further,
there is considerable scope for increasing the rice production even with the existing
technology, if countries like India, which have low yield, achieve the levels achieved
by China, which was comparable to the present yield in India in the year 2000. Even
within India there is a wide variation in yields in different states. While the average
yield for the whole country in 2007 was 3.21 tons/hectare, it was 5.80 tons/ hectare in
Punjab.
Published data is not available on the effect of enrichment of the atmosphere
by higher concentration of CO2, but the result is bound to be positive as in the case of
wheat, cotton and other plant species.
One can conclude from the above discussion that climate change will have
no adverse effect on global rice production and in fact there is considerable scope for
increasing rice production in the coming years to keep pace with the increasing
global demand with the anticipated growth in global population.
Vijaya Singh
16.11
Maize
Maize is the third most important food crop and the forecast of its global
production for the year 2008-2009 was 774 million tons over 146 million hectares of
cultivated area. Only a part of it is used directly as human food while the rest is used
for making beer, as poultry feed and, in recent years, increasingly for making ethanol
and other chemicals.
Maize is cultivated under tropical, sub-tropical and temperate climatic
conditions between 58oN and 42oS latitudes in areas having annual average temperature
ranging between 18oC and 24oC. The biggest producer of maize is USA accounting for
about 30% of global production, while China accounts for 15% and the European
Union 14%. Other important producers of maize are, Brazil, France, Argentina, Rumania
and Indonesia. India produces only about 3% of the global production.
The highest yield per hectare is 10 tons/hectare in USA while it is 5t/he in
China and Rumania; 7.7 t/he in Egypt, Italy and Canada and only 2t/he in India.
These figures bring out the potential of increasing the production of maize by using
the right technologies and providing the required inputs. Increase of a few degrees in
global temperature is not going to affect production of maize as cultivation is already
being done and high yields are being obtained under a wide range of climatic conditions.
Overall Effect of Climate Change on Global Food Production
In an article titled “Effects of Climate Change on Global Food Production
Under SRES Emissions and Socio-economic Scenarios” by M.L. Perry, Rozenzeweig,
A.Iglesias, M. Livermore and G. Fischer, published in April 2004 Issue of Science
Direct, it has been concluded that the world, for the most part, appears to be able to
continue to feed itself under the SRES scenarios during the rest of this century.
However, this outcome is achieved through production in the developed countries
(which mostly benefit from climate change) compensating for the decline projected
for the most part for the developing nations.
It is to be expected that global warming will require suitable adaptation to be
done in areas having different climatic conditions. The cold areas will benefit from
global warming, while the warmer areas will get affected adversely. However, the
overall global picture is not alarming.
Oceans
Global warming will affect the oceans in various ways which will have a profound
influence on the global ecosystem. Receding glaciers, melting of the polar ice and
expansion of sea water due to rise in temperature, will raise the Mean Sea Level
(MSL). The surface water of oceans will become warmer while the lower layers will
remain largely unaffected. This will affect the formation and movement of ocean currents.
Melting of ice at the poles will reduce the salinity and density of sea water in that
region while the faster evaporation at the sea surface will increase the salinity and
density of sea water in the top layers in the tropical region. These changes will also
16.12
Global Warming Has Its Compensations
affect the movement of ocean currents. Ice is a good reflector of sunlight and reduction
in the area of ice cover on land and over the oceans will also contribute to global
warming.
The extent of all the above changes will depend upon the actual rise in
temperature, which may take place during the next hundred years. As has been
stated above, the expected increase varies from 1.4oC to 5.8oC, depending upon the
emission scenarios considered and the models adopted for making the projections.
This uncertainty is reflected in the extent of the rise in the MSL by the end of the 21st
century and the projections vary from 0.09m (3.5”) to 0.88m (35.2”). It is to be noted
that all the water from molten ice will not go to increase the MSL and some of it will go
to increase the amount of water vapor in the atmosphere. It is estimated that for every
increase of 1oC in temperature there will be about 7% increase in the concentration of
water vapor in the atmosphere. Further, higher temperature and evaporation will result
in the formation of more clouds, higher rainfall, more water in the rivers and lakes and
more water in the subsurface reservoir of fresh water. This quantity will be considerable
and only the balance will go to increase the MSL.
It is difficult to make a theoretical analysis of all these aspects as many
variables are involved and the best guide is the historical records of the actual
observations. The global MSL has risen by 0.1-0.2 mm per year during the last 300
years and by 1-2 mm per year since 1900. Assuming that the higher figure of 2mm
per year will be maintained over the next 100 years, the total rise in the MSL by the
end of the 21st century will be only 20cm (8”). The fear that this much increase in the
water level over a period of 100 years will result in the submergence of many islands,
erosion of the present coast line, destruction of beaches, damage to mangroves,
saline water making in roads into coastal areas and also increasing the salinity of
underground water, appear to be exaggerated. Increase in rainfall and more fresh
water in the rivers may in fact neutralize the increase in salinity as a result of the rise
in MSL and the overall effect may be positive in coastal areas .There have been much
bigger changes in the coast line on account of natural causes in the past and some
of them might have been sudden or over a short period and the people successfully
adapted to these changes. Dwarka, the capital city of Lord Krishna, was a great city
but is now under water and so also the great city of Alexandria from where Cleopatra
ruled a great empire.
The possible increase in the frequency of El Nino events, increase in storm
frequency and intensity, increase in the height of waves, causing damage to coastal
areas and adverse effect on ocean currents, are speculative and there is no scientific
or historical evidence in their support. In fact, the mechanisms by which the above
phenomena are caused are not understood and there is no scientific basis for the
assumption that global warming will have an effect, which is negative for the global
ecosystem. No increase in the height of waves has been observed in recent years.
There has been cooling of the tropical eastern Pacific Ocean, which has remained
unexplained.
Vijaya Singh
16.13
Effect on Marine and Coastal Ecosystems and Availability of Sea Food
As has been discussed above, global warming will result in an increase in
the temperature of top layers of water in the oceans which, will affect the movement of
ocean currents and in the concentration of CO2 in the atmosphere and in sea water.
These changes will have a profound effect on the ecosystems of oceans and coastal
areas. The magnitude of the changes will depend upon different scenarios, which
may materialize.
Enrichment of sea water with CO2 will occur as a result of direct contact of air
rich in CO2 with the ocean surface, and rain water dissolving more CO2 while passing
through the atmosphere having higher concentration of CO2 and then finding its way
into the oceans. The increase in the concentration of CO2 in sea water combined with
increase in temperature will create favorable conditions for the growth of protozoa,
planktons and weeds which serve as food for fish and other forms of marine life. This
will also promote the growth of corals, except in areas where the temperature is
already too high; but the adverse effect in these areas will be compensated by creation
of more favorable conditions in higher latitudes where the existing temperature is too
low for survival of corals.
If the oceans make inroad into land, the shallow water in the submerged
area will be good breeding ground for marine life. Aquaculture is picking up rapidly in
coastal areas and it is estimated that it accounts for about 30% of commercial
production of sea food. This is a good development as vast areas of barren land are
available which can be converted into highly productive source of sea food.
Fear has been expressed that the growth of planktons and weeds may create
conditions favourable for spread of disease among marine life in the oceans and in
aquaculture fisheries and there may be an outbreak of algal blooms in coastal areas.
It goes without saying that an environment, which is favorable for growth of life, will be
good for all forms of life, desirable and undesirable; but there is no reason to believe
that the undesirable forms will be predominant and will have an edge over the desirable
ones.
Another fear which is expressed is that the saline sea water will make inroads
into coastal areas making them unsuitable for agriculture and that mangroves and
salt marshes may also be adversely affected, particularly where there is no scope for
their inward movement due to pressure of population. Mangroves and salt marshes
are generally not located close to thickly populated areas and this fear is not well
founded.
As regards the increase in the salinity in the river water and underground
water in coastal areas, as a result of sea water making inroads into the rivers and
coastal areas, the increase in the discharge of rivers and increase in the seepage of
fresh water into the underground reservoir as a result of increase in rainfall, will
effectively counteract it.
16.14
Global Warming Has Its Compensations
The effect of global warming in the polar regions will be more profound. New
coast lines will be created as a result of melting of ice and new marsh lands will come
up. Some areas of oceans which remained covered with ice will become navigable
and mineral deposits, which were inaccessible, will get exposed and will give rise to
new industries and population centers. The living space available to polar bear, pelican,
whales and other species which require very cold climate for survival, will shrink and
this may pose danger to their survival. On the other hand, the growing season for
vegetation in the polar region will get lengthened at the rate of 1.2 to 3.6 days per
decade and this combined with enrichment of atmosphere with CO2 will promote the
growth of alpine vegetation in these areas. Warming of lake water and shorter duration
of ice cover over them will also make the environment less favorable for some species
and more favorable for others.
Global warming and climate change will be a slow process and plant and
animal species will keep on migrating to areas having more favorable climatic conditions
keeping pace with the climate change. There will be movement of species towards
higher latitudes and higher altitudes in search of cooler climate. Of course there will
be natural and human barriers to prevent such migration in some areas, but the
overall pattern will be as suggested above.
In very dry and arid areas, the soil will dry up rapidly due to increase in
temperature and this will adversely affect the plant growth but this will be compensated
by CO2 enrichment and higher concentration of water vapour in the atmosphere. It is
difficult to predict whether the net effect will be positive or negative.
More Warmth for Residents of Cold Countries
Winters are a difficult period for people living in cold countries. With the
increase in temperature as a result of global warming, the winters will be less oppressive
and the number of days for which they have to remain cooped up inside their houses
will reduce. The period of spring and summer will get extended and they will be able
to go to the beaches and play outdoor games for more days.
A major portion of energy consumption in cold countries is for heating their
residences and work areas. There will be saving in energy consumption on heating as
a result of global warming and corresponding reduction in the consumption of fossil
fuels and emission of CO2 into the atmosphere.
The conditions in areas having warm climate will become more oppressive
but the adverse effect will be mitigated to some extent by the increase in the cloud
cover and heavier and more frequent rainfall, which would have a cooling effect.
Nature’s Self-correcting Mechanism
The global warming is attributed primarily to increased emission of greenhouse gases, out of which CO2 is most important and the emission of which has
Vijaya Singh
16.15
increased sharply during the past few decades, particularly from thermal power houses
and other industries and automobiles. It has been observed that out of the total emission
of CO2 as a result of human activity, only about 50% is accounted for by the increase
in the concentration of CO2 in the atmosphere. The remaining 50% is consumed by
vegetation and the oceans which act as sinks for CO2. Atmosphere enriched with
CO2 results in faster growth of plants and increased consumption of CO2. Similarly,
ocean water having higher concentration of CO2 leads to faster growth of marine life
and carbon which goes to form shells and corals will remain locked up for centuries.
Greening of mountain slopes due to receding glaciers and greening of land
exposed due to melting of ice in polar regions, will also result in increase in the
consumption of CO2.
All the above processes will get accelerated with the increase in the
concentration of CO2 in the atmosphere and will tend to bring it down till such time a
balance is reached and there is no further increase in the concentration of CO2.
Conclusion
There is no doubt that global temperatures have been going up and the rate
at which they have been going up has picked up during the last few decades. It is also
accepted that this global warming is partly on account of natural forces and partly on
account of human activity, but which of them has a dominant role is debatable. Global
warming will have an effect on environment and the life of people will depend upon its
extent, the estimates for which vary from 1.4oC to 5.8oC by the end of the 21st Century.
Some of the effects on the environment will be unfavorable for human and other forms
of life while there will be some others which are favorable. A lot of emphasis has been
laid on the negative effects in the debate on environment raging at present in scientific
journals and printed and electronic media, which play an important role in educating
the public. In this article an attempt has been made to highlight the positive effects
also so that a balanced view can be taken of developments in future.
One positive effect will be the faster and healthier growth of plants as a result
of enrichment of the atmosphere with CO2 coupled with an increase in temperature
and humidity. There will be an increase in forest area due to greening of mountain
slopes exposed by receding glaciers and the land exposed in the polar region due to
melting of ice. There will be significant increase in the yield of food grains and other
agricultural products due to CO2 enrichment, which will offset the negative effects and
the fear that global warming may lead to drop in global food production is not justified.
There will be increase in rainfall and availability of fresh water for irrigation and domestic
consumption, and there will also be an increase in the potential for hydroelectricity
and wind power. Oceans will work as sinks of CO2 and the availability of sea food will
improve.
Nature has its own self-correction mechanism for countering the adverse
effects of human activity, and this mechanism, together with the corrective measures
16.16
Global Warming Has Its Compensations
being taken all over the world to bring down the causes and the adverse effects of
global warming, it is hoped, will ensure a happy ending to the Twenty First Century.
References
1.
IPCC Third Assessment Report- Climate Change 2001:
http://w.w.w.grida.no/publications/other/ipec%5Ftar/?src=/climate/ip...
2.
Image Global Warming Predictions.png.
http://w.w.w.globalwarmingart.com/wiki/image:Global_Warming_Pre...
3.
Science Direct-Global Environment Change: Effects of climate change…
http://w.w.w.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V...
4.
Wheat in the World-B.C.Curtis.
http://w.w.w.fao.org/DOCREP/006/Y4011E/y4011e04.htm
5.
Rice trade: B2B Marketplace.
http://w.w.w.rice-trade.com/climatic-conditions—rice.html
6.
GLOBAL ENVIRONMENTAL CHANGE.
w.w.w.elsevier.com/locate/gloenvcha
7.
Korean Journal of Agricultural and Forest Meteorology,Vol.8,
No.4,(2006),pp.229-241.
8.
Bridging the Rice Yield in China - Zhu Defeng.
http://w.w.w..fao.org/docrep/003/x6905e/x6905e08.htm
9.
Maize Production Environment Revisited: A GIS Based Approach.
http://w.w.w.cymmyt.org/Research/NRG/map/Research_results/nrg_paper
10.
Perry, M.L., Rozenzeiweig, Iglesias, A., Livermore, M. and Fischer, G.: ‘Overall
Effect of Climate Change on Global Food Production’.
11.
Doiring III, Otto C., Randolf, J.C., Southworth, Jane, Pfeifer, Rebecca A .
(Ed.): Effects of Climate Change and Variability on Agriculture Production
System.
*****