Composition and Structure, Global Warming, Earth’s Energy Balance, Greenhouse Effect, Climate Change over Time, Glacier and Inter-Glacier Age and its correlation to CO2 level, Climate Change and its Impact on Bangladesh, Mitigation.

1. Climate Change and
Global Warming
Chapter outlines: Atmosphere:
Composition and Structure, Global Warming,
Earth’s Energy Balance, Greenhouse Effect,
Climate Change over Time, Glacier and
Inter-Glacier Age and its correlation to CO2
level, Climate Change and its Impact on
Bangladesh, Mitigation.
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2. Major components of Earth’s
atmosphere today
Gas % volume
Nitrogen, N2 78
Oxygen, O2 21
Argon, Ar 0.9
Water vapor, H2O 0.00001 (S. Pole)
4.0 (tropics)
Carbon Dioxide, C02 0.037 (370ppm)
The concentrations of CO2 and methane have increased
by 36% and 148% respectively since 1750 [1].
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3. • Ozone absorbs dangerous UV radiation
• Misconception: Ozone depletion doesn’t have Global
Warming effect[2]
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4. Global Warming
• Global warming is the increase in the average
temperature of Earth's near-surface air and oceans
since the mid-20th century and its projected
continuation.
• According to the 2007 Fourth Assessment Report by
the Intergovernmental Panel on Climate Change
(IPCC), global surface temperature increased by
0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th
century. [3]
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5. • Most of the observed temperature increase since
the middle of the 20th century has been caused by
increasing concentrations of greenhouse gases,
which result from human activities such as the
burning of fossil fuel and deforestation.[4][5]
• An increase in global temperature will cause sea
levels to rise and will change the amount and
pattern of precipitation, probably including
expansion of subtropical deserts.[6]
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Global Warming

6. • Warming is expected to be strongest in the Arctic
than Antarctica because of much land on northern
hemisphere than southern and would be associated
with continuing retreat of glaciers, permafrost and
sea ice. Other likely effects include more frequent
and intense extreme weather events, species
extinctions, and changes in agricultural yields.
Warming and related changes will vary from region
to region around the globe, though the nature of
these regional changes is uncertain.
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Global Warming

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8. Earth’s energy balance
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10. Blasing, T. J. (February 2013), Current Greenhouse Gas
Concentrations, doi:10.3334/CDIAC/atg.032, on CDIAC 2013.
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11. Greenhouse Effect NOT BAD Keeps Earth’s
Temperature Optimum
Greenhouse Mechanism:
Solar radiation (45%) reach the Earth
surface but a little or most of it
cannot go out make the Earth warm.
The outgoing radiation is IR (infrared)
has lower energy level than visible
light.
Low energy = Low capacity to pass
through the cloud, atmospheric dust
or CO2 . [ Wavelength = 1/ Energy ]
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12. Earth Axis is Tilted
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Tilted Axis creates
Precession

13. Climate Change :
Milanković Cycle
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14. Glacial age or ice cover occur every
100000 yr cycle in graph (a), (b)
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Inter Glacial age warming effect started
18000 year before from now in graph (c), (d)

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Huge Temperature variability within
decades observed in graph (e)
Global Warming in 20th Century
started from here

17. Temperature variability and CO2 level has
high correlation
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18. Summary
• Climate change happened in historic time and
sometime too frequently within decades. The
Medieval warming period was not correlated with
higher CO2.
• But in the modern era, temp. and CO2 have been
rising together.
• This suggests that two things are happening—one
process of variability due to nature, one due to
CO2.
• Natural causes: Earth’s rotation on its axis or orbit
changes in its angle and vibration result in climate
change within 100000 or 20000 year cycle
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19. IPCC prediction:
• The IPCC anticipates a warming of 1.1 °C to 1.4 °C
by the end of the 21st century.
Possible IMPACT on Bangladesh:
Rise of sea level range from 0.18 to 0.59 m
Average height of Bangladesh is 1 m form sea level
More frequent and intense extreme weather
events, and changes in agricultural yields
Drought situation likely to be increase
Salinity increases in the soil of coastal zone
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20. Mitigation
• Reduce greenhouse gas emission at least half
of present emission within 2020.
• Use of Alternative energy: wind, solar energy
• Use of carbon sink to store atmospheric
carbon; i.e., Planting tree
• Salinity and drought tolerant crop variety
cultivation and new search for variety
• Rainwater harvesting in deep ponds to solve
drought situation
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21. Reference
• [1]EPA (2007). "Recent Climate Change: Atmosphere Changes". Climate Change
Science Program. United States Environmental Protection Agency.
http://www.epa.gov/climatechange/science/recentac.html. Retrieved 21 April
2009.
• [2]Ramaswamy, V.; Schwarzkopf, M.D.; Shine, K.P. (1992). "Radiative forcing of
climate from halocarbon-induced global stratospheric ozone loss". Nature 355
(6363): 810–812. doi:10.1038/355810a0 .
• [3] IPCC (2007-05-04). "Summary for Policymakers" (PDF). Climate Change 2007:
The Physical Science Basis. Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change.
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf. Retrieved
2009-07-03.
• [4]"Understanding and Responding to Climate Change". United States National
Academy of Sciences. 2008.
http://americasclimatechoices.org/climate_change_2008_final.pdf. Retrieved 30
May 2010.
• [5]America's Climate Choices: Panel on Advancing the Science of Climate Change;
National Research Council (2010). Advancing the Science of Climate Change.
• [6]Lu, Jian; Vecchi, Gabriel A.; Reichler, Thomas (2007). "Expansion of the Hadley
cell under global warming" (PDF). Geophysical Research Letters 34 (6): L06805.
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22. • For more curiosity about this important issue
please see the FAQ = Frequently Asked
Questions of IPCC = Inter Governmental Panel
on Climate Change given in the resource
centre as a PDF.
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