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Introduction
Various human activities especially industrial ones add emissions to the atmosphere. Such
gases/particles emitted have not been part of the atmosphere ever. ‘Climate change’
encompasses the wide variety of accompanying impacts on temperature, weather patterns
and other natural systems. What is unique about current global climate change, relative to
historical changes, is the causal role of human activity (also called anthropogenic forcing)
and the current and projected dramatic changes in climate across the globe.
“Climate change is happening. Over the 20th century, the global average temperature has risen by about
0.6 °C, and the mean temperature in Europe has increased by more than 0.9 °C. Globally, the 10
warmest years on record all occurred after 1991.”
- European Commission strategy “Winning the Battle against Global Change”
Heat-trapping ‘greenhouse gases’ in the
atmosphere (of which the two most important
are water vapor and carbon dioxide, CO2) let
through short-wave radiation from the sun
but absorb the long-wave heat radiation
coming back from the Earth’s surface and re-
radiate it. These gases act like a blanket —
and keep surface and lower atmosphere about
33° C warmer than it would be without them.
Earth’s greenhouse blanket is a good balance
between the extremes of our neighbours:
Mars, without any greenhouse gases, is a
frozen wasteland; whilst Venus remains
trapped in a dense blanket of hot CO2.
1. Solar radiation passes through the clear
Various human activities including burning of atmosphere.
fossil fuels, and long-term deforestation,
humans have been increasing the 2. Most radiation is absorbed by the Earth's
surface and warms it.
concentration of CO2 and other greenhouse
gases in the atmosphere since the industrial 3. Some solar radiation is reflected by the Earth
revolution began, thickening the greenhouse and the atmosphere.
blanket. The enhanced concentration of 4. Infrared radiation is emitted from the Earth's
greenhouse gases is believed to be responsible surface.
for raising the mean temperature of the
5. Some of the infrared radiation is absorbed and
earth’s surface above that occurring due to the re-emitted by the greenhouse gases.
natural greenhouse effect (Effect of
greenhouse gases without human activities).
A prominent and consistent indicator of climate change is the retreat of mountain glaciers, a
worldwide phenomenon. Impacts on ice are also clear around the poles. The Arctic ice cap is
shrinking, whilst in Antarctica, massive calving of the Larsen Ice Shelf combined with rapid
rise in local temperatures around the Antarctic peninsula has led scientists to predict its
complete disappearance within decades. Another widely observed impact is the ‘bleaching’
of coral reefs caused at least in part by rising sea-surface temperatures.
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Alpine Glacier: comparison of present to 1900: Pasterze Glacier in Kärtnen, Austria
Circa 1900 Present
Photo Source: Munich Society for Environmental Research
Temperature changes around the world in the last quarter of the 20th century
Temperature rise is due to Human activities
Source: Intergovernmental Panel on Climate Change, Third Assessment, Climate Change 2001: Synthesis Report
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View from the other side
While answer of the absolute majority of scientists to the question “ Is there a Climate
Change?” would be yes, this does not mean that 100 % of the scientists now support climate
change as an absolute fact. There are alternative explanations
1. The sun may have warmed over the last 25 years and caused most if not all the warming
as discussed
2. Fossil fuel combustion releases heat directly to the atmosphere and will cause a warming
over the continents.
3. Urban heat islands are substantial (several degrees Celsius in many cases and larger than
the predicted anthropogenic greenhouse gases warming). Placing thermometers near
cities and downwind of cities may lead to a warming that is falsely attributed to
greenhouse gases.
4. Other explanations for the recent warming include increased intensity of El Niño,
increase in aerosols in the atmosphere and reduction in atmospheric ozone.
The fact is that projecting climate change is a complex exercise. Although the basic
mechanisms of climate change are straightforward, the final consequences for temperature
and specific impacts can be extremely hard to quantify. The role of the oceans, which store
vast amounts of heat and move it around in ocean currents, is complex. This introduces
some deep uncertainties into efforts to quantify climate change. Greenhouse gases will in
aggregate warm the surface, but by how much and how fast only becomes clearer as the
warming signal emerges more and more clearly from amidst all the other influences. Even
then, it is very hard to disentangle the effect of the oceans’ thermal inertia from the actual
‘climate sensitivity’ — slow warming may be a sign either of low atmospheric sensitivity, or it
may show that decades more unavoidable climate change remains pent up in the slowly
warming oceans. The chaotic nature of weather itself (as opposed to the ‘climate envelope’)
makes regional climate changes and extreme events even harder to predict, and scientists are
only slowly moving towards greater confidence about such effects.
The understanding of climatic system is evolving, but the fundamentals are clear and
supported by a long list of other accumulating impacts.
Probable impact and implications
There are clear trends in terms of warming, glacier retreat, sea-level rise, the migration and
loss of species and ecosystems. There are various other predicted impacts of climate change;
the list of these impacts could grow only longer as our understanding of multi-layered effects
of climate change grows.
Rising sea levels along with probable changes in storm patterns could have huge
consequences for hundreds of millions of people living in coastal cities; delta regions such as
the Nile Delta, lower Bangladesh, and parts of Florida, may be almost impossible to protect.
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If sea level rises by 1 meter, the Maldives will disappear entirely, and in Grenada, up to 60
per cent of the beaches would disappear in some areas following a 50-centimetre level rise.
“It is not just island people who are at risk from climate change: 60% of humanity live in coastal areas
and therefore share vulnerability to climate change and sea level rise. Low lying coastal areas in all
countries are threatened, including agriculturally productive river deltas world wide.”
Extreme weather events potentially have the greatest impacts on humans, but since they
occur infrequently, trends are hard to prove. Warming increases evaporation and
precipitation, and both aggregate rainfall and occurrences of ‘heavy precipitation events’ in
northern mid-latitudes the principal cause of flooding, which have increased in recent
decades. In tropical regions, the potential for more intense hurricanes and typhoons
increases in a warmer world, but the data are sufficiently sparse and complex that the
defining a trend remains in dispute. It may always be questionable to attribute any one
particular weather event to climate change, because all weather events have multiple causes.
But science is increasingly able to estimate ‘how much have past emissions increased the risk
of such events?’ – and the chances, at least of extremes such as these, are rising.
Following graph shows a dramatic rise in number of extreme weather events globally, partly
driven by regional climatic factors (E. g. changes in precipitation and flooding).
Source: Intergovernmental Panel on Climate Change, Third Assessment, Climate Change 2001: Synthesis Report
Some of the very likely changes predicted (with more than 90% confidence) are
Higher maximum temperatures, with more hot days and heat waves over nearly all land
areas. This would increase heat-related deaths, as well as heat-related stresses on crops.
Higher minimum temperatures, fewer cold days, frost days and cold waves over nearly
all land areas.
More intense precipitation events, resulting in increased floods, landslide, avalanche, and
mudslide damage, with increased soil erosion and increased flood run-off.
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In densely populated areas such as the Indian subcontinent, it could create problems such as
Rising seas and storms inundating the Ganges delta region; a more variable monsoon
undermining the agricultural foundations that feed a quarter of a billion people; and
changing patterns of river flow as climate change impacts the Himalayan glaciers that
feed the rivers, with corresponding international tensions across already volatile borders.
Act now Too late or too soon?
The climate system is marked by the inertia involved. Atmospheric greenhouse gas
concentrations will not stabilise until global greenhouse gas emissions are reduced to a small
fraction of today’s levels, which is not expected by 2100. Even if the CO2 concentration
stabilizes, global temperatures will continue to rise for decades as the oceans slowly adjust to
the higher heat input. Sea levels will rise due to both thermal expansion and ice melt –
effects which will accumulate over hundreds to thousands of years respectively.
CO2 Concentration, Temperature and sea level continue to stabilize over a long period
Source: Intergovernmental Panel on Climate Change, Third Assessment, Climate Change 2001: Synthesis Report
There are uncertainties about complex interacting systems such as North Atlantic Ocean
circulation, monsoon in South Asia subcontinent, rainforest and permafrost. Their dynamics,
stability and their limits are not well understood. Predicting specific changes to such complex
systems is filled with uncertainty. By the time the limits are understood — they may already
be crossed, possibly with dramatic consequences. The time to act on this issue is now, preparing in
every possible way for adapting to climate change which is already pent up and unavoidable.
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References
The Climate Change Challenge: Scientific evidence and implications. Carbon Trust.
IPCC, Third Assessment, Climate Change 2001: Synthesis Report
UNFCCC (2005) climate change, small island developing States
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EcoLogic Consultancy is a start-up consulting firm in the field of Environment Management.
It provides services in wide spectrum of environmental field to help our clients to identify the
opportunities, harness the potential, and solve their environmental challenges.
For further details and discussion, you can reach us at
enquiry@ecologicconsultancy.in / ecologicconsultancy@gmail.com
020-400 96 279 / +91-90287 88430
www.ecologicconsultancy.in
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