GLOBAL WARMING - AN OVER VIEW
Fig.1 One of the most important effects that future
generation is going to face is the significant rise in sea levels
due to global warming
Introduction
Climate change is a major environmental problem that is
affecting the Earth. The global community has recognised the need to combat
climate change. The challenge is to adopt a long term strategy to mitigate the
emissions & to develop cleaner technologies that protect the environment
without affecting the economic development. Global platforms like UNFCCC1
is working towards this objective & succeeded in developing documents &
methodologies like Kyoto Protocol, CDM2, Copenhagen Accord etc. in
consensus with the member countries.
Global Warming, Green House Gases and GHG effect
In 1908, a Swedish scientist, Svante August Arrhenius argued that the greenhouse effect from coal
and petroleum use is warming the globe and this is considered to be the first
such warning from the scientific world on the issue.
Life on earth is made possible by energy from the sun,
which arrives mainly in the form of visible light. About 30 percent of the
sunlight is scattered back into space by outer atmosphere and the balance 70
percent reaches the earth's surface, which reflects it in form of infrared
radiation. The escape of slow moving infrared radiation is delayed by the green
house gases. A thicker blanket of greenhouse gases traps more infrared
radiation and increase the earth's temperature. Greenhouse gases makeup only 1
percent of the atmosphere, but they act as a blanket around the earth, or like
a glass roof of a greenhouse and keep the earth 30 degrees warmer than it would
be otherwise - without greenhouse gases, earth would be too cold to live!
Human activities that are responsible for making the greenhouse layer
thicker are emissions of carbon dioxide from the combustion of coal, oil and
natural gas; by additional methane and nitrous oxide from farming activities
and changes in land use; and by several man made gases that have a long life in
the atmosphere.
Fig.2 Svante August Arrhenius (1859–1927)
The increase in greenhouse gases is happening at an alarming rate. If
greenhouse gases emissions continue to grow at current rates, it is almost
certain that the atmospheric levels of carbon dioxide will increase twice or
thrice from pre-industrial levels during the 21st century. Even a small
increase in earth's temperature will be accompanied by changes in climate such as
cloud cover, precipitation3, wind patterns and duration of seasons.
In an already highly crowded and stressed earth, millions of people depend on
weather patterns, such as monsoon rains, to continue as they have in the past.
Even minimum changes will be disruptive and difficult. Carbon dioxide is
responsible for 60 percent of the "enhanced greenhouse effect".
Humans are burning coal, oil and natural gas at a rate that is much faster than
the rate at which these fossil fuels were created. This is releasing the carbon
stored in the fuels into the atmosphere and upsetting the carbon cycle (a
precise balanced system by which carbon is exchanged between the air, the
oceans and land vegetation taking place over millions of years). Currently,
carbon dioxide levels in the atmospheric are rising by over 10 percent every 20
years.
Most abundant Green House Gases are: Carbon Dioxide, Water vapour, Methane, Nitrous Oxide,
Ozone & Chloroflouro Carbons.
Current Evidence of Climatic Change
Numerous long-term changes in the climate have been observed, including
extreme weather such as droughts, heavy precipitation, heat waves and the
intensity of tropical cyclones.
Ø Trends towards more powerful storms and hotter, longer
dry periods have been observed and are assessed in the IPCC’s4 Fourth
Assessment Report. Warmer temperatures mean greater evaporation, and
a warmer atmosphere is able to hold more moisture -- hence there is more water
aloft that can fall as precipitation. Similarly, dry regions are apt to
lose still more moisture if the weather is hotter; this increases the severity
of droughts and desertification.
Ø The frequency of heavy precipitation events has
increased over most land areas. Significantly increased precipitation has
been observed in eastern parts of North and South America, northern Europe
and northern and central Asia. There is also observational evidence for an
increase of intense tropical cyclone activity in the North Atlantic since
about 1970.
Ø Drying has also been observed over large regions, i.e.
the Sahel5, the Mediterranean, southern Africa and parts of
southern Asia.
 |
Fig. 3 The Green House Effect (Courtesy: www.wikipedia.org)
Fig.4
GHG Emissions Details (Courtesy www.wikipedia.org)
Ø In Africa's large catchment basins of Niger, Lake Chad,
and Senegal, total available water has decreased by 40 to 60 per cent, and
desertification has been worsened by lower average annual rainfall, runoff,
and soil moisture, especially in southern, northern, and western Africa.
Ø The Rhine6 floods of 1996 and 1997, the
Chinese floods of 1998, the East European floods of 1998 and 2002, the
Mozambique and European floods of 2000, and the monsoon-based flooding of
2004 in Bangladesh (which left 60 per cent of the country under water), are
examples of more powerful storms.
|
Ø Average Arctic temperatures increased at almost
twice the global rate in the past 100 years. Temperatures at the top of
the permafrost7 layer have generally increased since the 1980s by up
to 3°C. In the Russian Arctic, buildings are collapsing because permafrost
under their foundations has melted.
Ø Snow cover has declined by some 10 per cent in the mid-
and high latitudes of the Northern Hemisphere since the late 1960s. Mountain
glaciers and snow cover have declined in both hemispheres and widespread
decreases in glaciers and ice caps have contributed to sea level rise. New data
evaluated by the IPCC shows that losses from the ice sheets of Greenland and
Antarctica have very likely contributed to sea level rise from 1993 to 2003.
The average global sea level rose at an average rate of 1.8 mm per year between
1961 and 2003, but between 1993 and 2003 it rose by 3.1 mm per year.
Ø Almost all mountain glaciers in non-polar regions
retreated during the 20th century. The overall volume of glaciers in
Switzerland decreased by two-thirds. Glaciers high in the Himalayas
are dwindling faster than anyone thought, putting nearly a billion people
living in South Asia in peril of losing their water supply.
Future Effects
Even the minimum predicted shifts in climate for the 21st century are
likely to be significant and disruptive. Predictions of future climatic changes
are wide-ranging. The global temperature may climb from 1.4 to 5.8 degrees C;
the sea level may rise from 9 to 88 cm. Thus, increases in sea level this
century are expected to range from significant to catastrophic. This
uncertainty reflects the complexity, interrelatedness, and sensitivity of the
natural systems that make up the climate.
Severe Storms and Flooding
The minimum warming forecast for the next 100 years is more than twice the
0.6 degree C increase that has occurred since 1900 and that earlier increase is
already having marked consequences. Extreme weather events, as predicted by
computer models, are striking more often and can be expected to intensify and
become still more frequent. A future of more severe storms and floods along the
world's increasingly crowded coastlines is likely.
Food Shortages
Although regional and local effects may differ widely, a general reduction
is expected in potential crop yields in most tropical and sub-tropical regions.
Mid-continental areas such as the United States' "grain belt" and
vast areas of Asia are likely to become dry. Sub-Saharan Africa where dry land
agriculture relies solely on rain, the yields would decrease dramatically even
with minimum increase in temperature. Such changes could cause disruptions in
food supply in a world is already afflicted with food shortages and famines.
Dwindling Freshwater supply
Salt-water intrusion from rising sea levels will reduce the quality and
quantity of freshwater supplies. This is a major concern, since billions of
people on earth already lack access to freshwater. Higher ocean levels already
are contaminating underground water sources in many parts of the world.
Loss of Biodiversity
Most of the world's endangered species (some 25 per cent of mammals and 12
per cent of birds) may become extinct over the next few decades as warmer
conditions alter the forests, wetlands, and rangelands8 they depend
on, and human development blocks them from migrating elsewhere.
Increased Diseases
Higher temperatures are expected to expand the range of some dangerous
"vector-borne"9 diseases, such as malaria, which
already kills 1 million people annually, most of them children.
A World under Stress
Due to the ongoing environmentally damaging activities such as overgrazing,
deforestation, and denuded agricultural soils, nature will be more vulnerable
than previously to changes in climate. Similarly, the world's vast human population,
much of it poor, is vulnerable to climate stress. Millions live in dangerous
places such as floodplains or in slums around the big cities of the developing
world. Often there is nowhere else for population to move. In the distant past,
man and his ancestors migrated in response to changes in habitat. There will be
much less room for migration in future.
Global warming almost certainly will be unfair. The industrialized
countries of North America and Western Europe, and other countries such as Japan,
are responsible for the vast amount of past and current greenhouse-gas
emissions. These emissions are incurred for the high standards of living
enjoyed by the people in those countries. Yet those to suffer most from climate
change will be in the developing world. They have fewer resources for coping
with storms, with floods, with droughts, with disease outbreaks, and with
disruptions to food and water supplies. They are eager for economic development
themselves, but may find that this already difficult process has become more
difficult because of climate change. The poorer nations of the world have done
almost nothing to cause global warming yet is most exposed to its effects. If
global warming continues, say scientists, our neighbouring country, the Maldives
could sink beneath the Indian Ocean within 100 years!
Acid Rain
Acid rain is
caused by release of SOX & NOX10 from combustion of fossil
fuels, which then mix water vapour in atmosphere to
form sulphuric and nitric acids respectively.
The effects of acid rain are as follows:
•
Acidification of lakes,
streams, and soils
•
Direct and indirect effects
(release of metals, For example: Aluminium which washes away plant nutrients)
•
Killing of wildlife (trees,
crops, aquatic plants, and animals)
•
Decay of building materials
and paints, statues, and sculptures
• Health problems (respiratory,
burning- skin and eyes)
Conclusion
Commitment & voluntary actions to tackle the
issues from international community like Nations, Corporate world,
Institutions, NGOs & individuals are necessary to yield the desired results
from time to time, in order to save our planet by creating awareness among the
general public, measurement of emissions, setting a reduction target, actions
to reduce GHGs, reporting and developing environment friendly technologies.
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Notes:
1. UNFCCC – United Nations Framework Convention on Climate
Change.
2. CDM – Clean Development Mechanism.
3. Precipitation – One of the three main processes that
contribute the hydrologic cycle.
4. IPCC – Intergovernmental Panel on Climate Change, United
Nations.
5.
The Sahel – An ecoclimatic and bio geographic zone of transition in North Africa between
the Atlantic & the Red Sea.
6.
The Rhine – One of the longest rivers in Europe.
8.
Rangelands – Vast natural landscapes in the form of grasslands,
shrublands, woodlands, wetlands and deserts.
9.
Vector-borne – Transmitted by an insect or any living carrier.
10.
SOx
& NOx – Sulphur Dioxide & Nitrogen Oxides. Sulphur Dioxide is not a
GHG.
References:
1. UNFCCC website (www.unfccc.int)
3. www.wiki.answers.com
4. Bureau of Energy Efficiency, India
5. Environmental Defence Fund, EDF Boston, MA, USA
Profile:
PS
Babu, B.Tech, MIIChE, PMP, MIE, CEng; experienced in construction, design & manufacturing projects in India
& abroad. Currently working as an independent Engineering & Project
Management Consultant.
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