1.
Illustration of Earth globe in
very hot climate change scene
Lecture
16
HRh

2.
Global warming and climate changeGlobal warming and climate change
 The The effects ofeffects of global warmingglobal warming are the ecological and social are the ecological and social
changes caused by the rise in global temperatureschanges caused by the rise in global temperatures
 ""Climate changeClimate change" means a change in climate that persists over a " means a change in climate that persists over a
sustained period of time. sustained period of time.
 Temperature changeTemperature change
 If no additional steps are taken to reduce emissions of carbon If no additional steps are taken to reduce emissions of carbon
dioxide and other problematic gases then by about the year 2035 dioxide and other problematic gases then by about the year 2035
the average temperature will be 1 the average temperature will be 1 oo
C higher than it was in 1990 C higher than it was in 1990
(IPCC)(IPCC)
 By 2100 it will increase by more than another 3 By 2100 it will increase by more than another 3 o o
CC
 Global temperature reaching 11000 years peakGlobal temperature reaching 11000 years peak
 Antarctic ice is melting 10 times faster than 1000 years agoAntarctic ice is melting 10 times faster than 1000 years ago
 Record level atmospheric CORecord level atmospheric CO22 reaches 400 ppm for the first time in reaches 400 ppm for the first time in
3 million years.3 million years.

3.
Global warming and climate change:Global warming and climate change: Physical impactsPhysical impacts
 Evidence of global warming are Evidence of global warming are
increasing temperature over land increasing temperature over land
and the ocean, and seaand the ocean, and sea levellevel rise, rise,
decreased snow cover in decreased snow cover in
the Northernthe Northern Hemisphere, and Hemisphere, and
declining Arcticdeclining Arctic seasea ice extentice extent
 Human-induced warming could Human-induced warming could
lead to large-scalelead to large-scale, , irreversibleirreversible, ,
and/orand/or abruptabrupt changes in physical changes in physical
systemssystems

An example of this is the melting An example of this is the melting
of iceof ice sheets, which contributes to sheets, which contributes to
sea level risesea level rise
 Regions which are dry at present Regions which are dry at present
will in general become even drier, will in general become even drier,
while regions that are currently while regions that are currently
wet will in general become even wet will in general become even
wetterwetter

4.
Ice cap melting,
the deadliest effect
of global warming
View of the Aletsch Glacier
in the Swiss Alps, which due to global
warming, has been decreasing

5.
Global warming and climate changeGlobal warming and climate change
 Extreme weatherExtreme weather
 Frequency, length and intensity of heatFrequency, length and intensity of heat waves will very likely waves will very likely
increase over most land areasincrease over most land areas
 Maximum windMaximum wind speed of tropicalspeed of tropical cyclones will increasecyclones will increase
 A number of regions may experience more intense droughtsA number of regions may experience more intense droughts
 Increases in heavyIncreases in heavy rainfall might contribute to increases in rainfall might contribute to increases in
local flooding in some catchments or regionslocal flooding in some catchments or regions
 Violent storms with more frequency and intensity Violent storms with more frequency and intensity
 Climate change threatens Indian monsoon.Climate change threatens Indian monsoon.

6.
Global warming and climate change:Global warming and climate change: Sea level riseSea level rise
 OceansOceans
(level, temp)(level, temp)
 Ongoing effects Ongoing effects
include rising include rising
sea levels due sea levels due
to thermal to thermal
expansion and expansion and
melting of melting of
glaciers and ice glaciers and ice
sheets, and sheets, and
warming of the warming of the
ocean surface, ocean surface,
leading to leading to
increased increased
temperature temperature
stratificationstratification
 A warmer Earth would result in rising sea levels for A warmer Earth would result in rising sea levels for
two different reasons: (1) When temperature in water two different reasons: (1) When temperature in water
increases, it expands and takes up more space; (2) increases, it expands and takes up more space; (2)
Warming of Earth would result in the melting of Warming of Earth would result in the melting of
glaciers, which would add more water to the oceans.glaciers, which would add more water to the oceans.
 A recent report (2012) suggests that Sea level will rise A recent report (2012) suggests that Sea level will rise
50% faster than as was projected by IPCC in 2007 50% faster than as was projected by IPCC in 2007
 World is heading for sea level rise of around World is heading for sea level rise of around aa metermeter
by century’s endby century’s end
 Results areResults are: : Flooding of low-lying islands andFlooding of low-lying islands and
coastal cities, flooding of coastal estuaries,coastal cities, flooding of coastal estuaries,
wetlands and coral reefs, beach erosion,wetlands and coral reefs, beach erosion,
disruption of coastal fisheries, contamination ofdisruption of coastal fisheries, contamination of
coastal aquifers with salt water, increase in thecoastal aquifers with salt water, increase in the
vulnerability of coastal areas to flooding fromvulnerability of coastal areas to flooding from
storm surges and intense rainfallstorm surges and intense rainfall
 Some 1700 US cities under threat of going underSome 1700 US cities under threat of going under
water by 2100.water by 2100.

7.
This is a topographic map
designed to emphasize portions of
Bangladesh that are near sea level
and hence could potentially be
vulnerable to sea level rise.
With a population of ~160 million,
Bangladesh has the highest
population density of any country.

8.
 In BangladeshIn Bangladesh, the land that sustains their lives disappears;, the land that sustains their lives disappears;
making hundreds of millions of climate refugees, and can lead tomaking hundreds of millions of climate refugees, and can lead to
resource wars and all kinds of conflictsresource wars and all kinds of conflicts
 If the temperature rises to 2.5 ºC then flood will increase in 29%If the temperature rises to 2.5 ºC then flood will increase in 29%
areaarea
Extreme drought will occur every 5 yearExtreme drought will occur every 5 year
 South west region will be the worst hit areaSouth west region will be the worst hit area
By the year 2050 cyclone with tidal upsurge of 3 meter heightBy the year 2050 cyclone with tidal upsurge of 3 meter height
will hit coastal areawill hit coastal area

9.
Effects of Global WarmingEffects of Global Warming
 ForestryForestry
Changes in forest compositionChanges in forest composition
and locationand location
Disappearance of someDisappearance of some
forestsforests
Increased fire from dryingIncreased fire from drying
Loss of wildlife habitat andLoss of wildlife habitat and
speciesspecies
 Food ProductionFood Production
Changes in crop yieldChanges in crop yield
Increased irrigationIncreased irrigation
demandsdemands
Increased pests, cropIncreased pests, crop
diseases and weeds indiseases and weeds in
warmer areaswarmer areas
Shift in food growingShift in food growing
areasareas

10.
Effects of Global WarmingEffects of Global Warming
 Water ResourcesWater Resources
Sea level rise will extend areasSea level rise will extend areas
of salinization of groundwater and estof salinization of groundwater and est
uaries, resulting in a decrease inuaries, resulting in a decrease in
freshwater availability for humans andfreshwater availability for humans and
ecosystems in coastal areasecosystems in coastal areas
Disruption in water cycleDisruption in water cycle
increase in evaporation will causeincrease in evaporation will cause
some areas to become driersome areas to become drier
(increased drought), while the(increased drought), while the
increased moisture in the air willincreased moisture in the air will
result in greater rainfall in other areas.result in greater rainfall in other areas.
Increased water pollution from coastalIncreased water pollution from coastal
floodingflooding
 WeatherWeather
extremesextremes
Prolonged heatProlonged heat
waves and droughtswaves and droughts
Violent storms withViolent storms with
more frequency andmore frequency and
intensityintensity

11.
Effects of Global WarmingEffects of Global Warming
 Human Population and HealthHuman Population and Health
Increased deaths from heat andIncreased deaths from heat and
diseases (malaria, dengue, yellowdiseases (malaria, dengue, yellow
fever, cholera, etc)fever, cholera, etc)
More environmental refugeesMore environmental refugees
Increased migrationIncreased migration
Disruption of food and water suppliesDisruption of food and water supplies
Spread of tropical diseases toSpread of tropical diseases to
temperate areatemperate area
Increased respiratory disease andIncreased respiratory disease and
pollen allergiespollen allergies
BiodiversityBiodiversity
Loss of habitatsLoss of habitats
Disruption of aquaticDisruption of aquatic
lifelife
Extinction of someExtinction of some
plant and animalplant and animal
speciesspecies
Penguin colonies toPenguin colonies to
decline by a thirddecline by a third
Lizard facing massLizard facing mass
extinction.extinction.

12.
Solutions to Global Warming QSolutions to Global Warming Q
Two basic adjustments to potential global warming are:Two basic adjustments to potential global warming are:
Mitigation through reduction of emissions of greenhouseMitigation through reduction of emissions of greenhouse
gasesgases
Do nothing to combat it and live with future global climateDo nothing to combat it and live with future global climate
changechange
However, if we are prudent we will plan to reduce emission ofHowever, if we are prudent we will plan to reduce emission of
greenhouse gasesgreenhouse gases
Require changes in land management and energy useRequire changes in land management and energy use
The larger the population & the greater the degree ofThe larger the population & the greater the degree of
affluence, the higher the consumption and the larger theaffluence, the higher the consumption and the larger the
emission of greenhouse gasesemission of greenhouse gases
Easier to stabilize GH emission ifEasier to stabilize GH emission if population growth is slowedpopulation growth is slowed
Energy efficiencyEnergy efficiency of automobiles & appliance—of automobiles & appliance—reduce thereduce the
emissionemission and willand will mitigate global warming.mitigate global warming.

13.
Effects of Global WarmingEffects of Global Warming
Planting treesPlanting trees
Carbon managementCarbon management
Sequester carbon dioxideSequester carbon dioxide
undergroundunderground
Renewable energyRenewable energy
Reduce deforestationReduce deforestation
Sustainable agricultureSustainable agriculture
including no-till agricultureincluding no-till agriculture
Limit urban sprawlLimit urban sprawl
Reduce povertyReduce poverty
Other strategies includeOther strategies include

14.
Ozone Layer Depletion QOzone Layer Depletion Q
 Ozone (OOzone (O33))
In the stratosphere, ozone acts as a protective shield againstIn the stratosphere, ozone acts as a protective shield against
damaging UV radiationdamaging UV radiation
90% of ozone in90% of ozone in the atmosphere is present in thethe atmosphere is present in the
stratospherestratosphere
Peak concentration of 300 ppv occurs at an altitude of 25 kmPeak concentration of 300 ppv occurs at an altitude of 25 km
near equator & 15 km over polar regionsnear equator & 15 km over polar regions
ItIt absorbsabsorbs approximatelyapproximately 99%99% ultraviolet (UV) radiationultraviolet (UV) radiation

15.
Ozone Layer DepletionOzone Layer Depletion
 The ozone layer can be depleted by free radical catalysts, includingThe ozone layer can be depleted by free radical catalysts, including
nitric oxide (NO), nitrous oxide (Nnitric oxide (NO), nitrous oxide (N22O), hydroxyl (OH), atomicO), hydroxyl (OH), atomic
chlorine (Cl), and atomic bromine (Br)chlorine (Cl), and atomic bromine (Br)
 While there are natural sources for all of these species, theWhile there are natural sources for all of these species, the
concentrations of chlorine and bromine have increased markedly inconcentrations of chlorine and bromine have increased markedly in
recent years due to the release of large quantities of man-maderecent years due to the release of large quantities of man-made
organohalogen compounds, especially chlorofluorocarbons (CFCs)organohalogen compounds, especially chlorofluorocarbons (CFCs)
and bromofluorocarbonsand bromofluorocarbons
 These highly stable compounds are capable of surviving the rise toThese highly stable compounds are capable of surviving the rise to
the stratosphere, where Cl and Br radicals are liberated by thethe stratosphere, where Cl and Br radicals are liberated by the
action of ultraviolet lightaction of ultraviolet light
 Each radical is then free to initiate and catalyze a chain reactionEach radical is then free to initiate and catalyze a chain reaction
capable of breaking down over 100,000 ozone moleculescapable of breaking down over 100,000 ozone molecules
 Ozone levels over the northern hemisphere have been dropping byOzone levels over the northern hemisphere have been dropping by
4% per decade4% per decade
 In 2009, nitrous oxide (NIn 2009, nitrous oxide (N22O) was the largest ozone-depletingO) was the largest ozone-depleting
substance emitted through human activities.substance emitted through human activities.

16.
Ozone Layer DepletionOzone Layer Depletion
Natural conditions prevailing in the stratosphere result inNatural conditions prevailing in the stratosphere result in
a dynamic balance between the creation and destructiona dynamic balance between the creation and destruction
of ozoneof ozone
Major culprit in ozone depletion are ‘Freons’ QMajor culprit in ozone depletion are ‘Freons’ Q
When they wander upward in the stratosphere, followingWhen they wander upward in the stratosphere, following
reactions take place:reactions take place:
CFCF22ClCl22 ++ hhvv →→ Cl* + CClFCl* + CClF22**
yields chlorine atoms, and attack Oyields chlorine atoms, and attack O33::
Cl* + OCl* + O33 →→ ClO* + OClO* + O22
ClO* + OClO* + O →→ Cl* + OCl* + O22
These two equations define a chemical cycle (catalyticThese two equations define a chemical cycle (catalytic
chain reaction) that can deplete ozonechain reaction) that can deplete ozone

17.
Ozone Layer DepletionOzone Layer Depletion
Future of Ozone DepletionFuture of Ozone Depletion
If the manufacture, use, and emission of all ozoneIf the manufacture, use, and emission of all ozone
depleting chemicals were to stop today the problemdepleting chemicals were to stop today the problem
wouldn’t not go away because millions of tons of thosewouldn’t not go away because millions of tons of those
persistent chemicals are now in the lower atmospherepersistent chemicals are now in the lower atmosphere
working their way to the stratosphereworking their way to the stratosphere

18.
Ozone Layer Depletion QOzone Layer Depletion Q
Environmental EffectsEnvironmental Effects
Serious potential environmental effects includeSerious potential environmental effects include damagedamage
to Earth’s food chains on land & in the oceans andto Earth’s food chains on land & in the oceans and
human health effects—increasing all types of skinhuman health effects—increasing all types of skin
cancers and cataracts and suppression of immunecancers and cataracts and suppression of immune
systemssystems

19.
Ozone Layer Depletion QOzone Layer Depletion Q
 Management Issues QManagement Issues Q
CollectionCollection && ReuseReuse
Develop ways to collect and reuse CFCsDevelop ways to collect and reuse CFCs
One company in Germany recycles approximatelyOne company in Germany recycles approximately
6000 refrigerators a month6000 refrigerators a month
 SubstitutesSubstitutes
Two substitutes—Two substitutes— hydrofluorocarbonshydrofluorocarbons andand
hydrochloro- fluorocarbons,hydrochloro- fluorocarbons, have advantageshave advantages
HFCS do not contain chlorineHFCS do not contain chlorine
Fluorine is 1000 times less efficient in causing ozoneFluorine is 1000 times less efficient in causing ozone
depletiondepletion

20.
Ozone Layer Depletion QOzone Layer Depletion Q
 Injection of ChemicalsInjection of Chemicals
Propane will react with chlorine forming hydrochloricPropane will react with chlorine forming hydrochloric
acid thus preventing chlorine to attack ozoneacid thus preventing chlorine to attack ozone
50,000 tons of propane might do the job50,000 tons of propane might do the job
Would be injected at an elevation of 15 kmWould be injected at an elevation of 15 km
Needs several hundred large aircraftNeeds several hundred large aircraft
 Short-term Adaptation:Short-term Adaptation:
Learning to live with an increase in exposure to UVLearning to live with an increase in exposure to UV
radiationradiation
Long-term achievement of sustainability requireLong-term achievement of sustainability require
management of anthropogenic Omanagement of anthropogenic O33-depleting chemicals-depleting chemicals

21.
Thermal Inversion of AirThermal Inversion of Air
Although the temperature near the Earth’s surfaceAlthough the temperature near the Earth’s surface
normally decreases with increasing altitude certainnormally decreases with increasing altitude certain
atmospheric condition can result in the oppositeatmospheric condition can result in the opposite
direction—direction—increasing temperature with increasingincreasing temperature with increasing
altitudealtitude, a condition characterized by high, a condition characterized by high
atmospheric stability called thermal inversionatmospheric stability called thermal inversion
By limiting vertical movement of air (turbulent mixing)By limiting vertical movement of air (turbulent mixing)
temperature inversions result in air stagnation and thetemperature inversions result in air stagnation and the
trapping of air pollutants in localized areastrapping of air pollutants in localized areas

22.
Thermal Inversion

23.
Picture showing the yellow haze
from the thermal inversion

24.
End of SlidesEnd of Slides