Illustration of Earth globe in very hot climate change scene

Lecture 16HRh

Global warming and climate changeGlobal warming and climate change

The The effects of effects 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 ooC 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.

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

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

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.

Global warming and climate change: Global warming and climate change: Sea level riseSea level rise

Oceans Oceans (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 and Flooding 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 of disruption of coastal fisheries, contamination of coastal aquifers with salt water, increase in the coastal aquifers with salt water, increase in the vulnerability of coastal areas to flooding from vulnerability of coastal areas to flooding from storm surges and intense rainfallstorm surges and intense rainfall

Some 1700 US cities under threat of going under Some 1700 US cities under threat of going under water by 2100.water by 2100.

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.

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 to making 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% areaareaExtreme drought will occur every 5 year Extreme drought will occur every 5 year

South west region will be the worst hit areaSouth west region will be the worst hit areaBy the year 2050 cyclone with tidal upsurge of 3 meter height By the year 2050 cyclone with tidal upsurge of 3 meter height will hit coastal areawill hit coastal area

Effects of Global WarmingEffects of Global Warming

ForestryForestry

Changes in forest composition Changes in forest composition and locationand location

Disappearance of some Disappearance of some forestsforests

Increased fire from dryingIncreased fire from drying

Loss of wildlife habitat and Loss of wildlife habitat and speciesspecies

Food ProductionFood Production

Changes in crop yield Changes in crop yield

Increased irrigation Increased irrigation demands demands

Increased pests, crop Increased pests, crop diseases and weeds in diseases and weeds in warmer areas warmer areas

Shift in food growing Shift in food growing areasareas

Effects of Global WarmingEffects of Global Warming

Water ResourcesWater ResourcesSea level rise will extend areas Sea level rise will extend areas of salinization of groundwater and estof salinization of groundwater and estuaries, resulting in a decrease in uaries, resulting in a decrease in freshwater availability for humans and freshwater availability for humans and ecosystems in coastal areasecosystems in coastal areas

Disruption in water cycleDisruption in water cycle

increase in evaporation will cause increase in evaporation will cause some areas to become drier some areas to become drier (increased drought), while the (increased drought), while the increased moisture in the air will increased moisture in the air will result in greater rainfall in other areas.result in greater rainfall in other areas.

Increased water pollution from coastal Increased water pollution from coastal floodingflooding

Weather Weather extremesextremes

Prolonged heat Prolonged heat waves and droughtswaves and droughts

Violent storms with Violent storms with more frequency and more frequency and intensity intensity

Effects of Global WarmingEffects of Global Warming

Human Population and HealthHuman Population and Health

Increased deaths from heat and Increased deaths from heat and diseases (malaria, dengue, yellow diseases (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 to Spread of tropical diseases to temperate areatemperate area

Increased respiratory disease and Increased respiratory disease and pollen allergiespollen allergies

BiodiversityBiodiversityLoss of habitatsLoss of habitats

Disruption of aquatic Disruption of aquatic lifelife

Extinction of some Extinction of some plant and animal plant and animal speciesspecies

Penguin colonies to Penguin colonies to decline by a thirddecline by a third

Lizard facing mass Lizard facing mass extinction.extinction.

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 greenhouse Mitigation through reduction of emissions of greenhouse gasesgases

Do nothing to combat it and live with future global climate Do nothing to combat it and live with future global climate changechange

However, if we are prudent we will plan to reduce emission of However, 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 of The larger the population & the greater the degree of affluence, the higher the consumption and the larger the affluence, the higher the consumption and the larger the emission of greenhouse gasesemission of greenhouse gases

Easier to stabilize GH emission if Easier to stabilize GH emission if population growth is slowedpopulation growth is slowed

Energy efficiencyEnergy efficiency of automobiles & appliance— of automobiles & appliance—reduce the reduce the emissionemission and will and will mitigate global warming.mitigate global warming.

Effects of Global WarmingEffects of Global Warming

Planting treesPlanting trees

Carbon managementCarbon management

Sequester carbon dioxide Sequester carbon dioxide undergroundunderground

Renewable energyRenewable energy

Reduce deforestationReduce deforestation

Sustainable agriculture Sustainable agriculture including no-till agricultureincluding no-till agriculture

Limit urban sprawlLimit urban sprawl

Reduce povertyReduce poverty

Other strategies includeOther strategies include

Ozone Layer Depletion QOzone Layer Depletion Q

Ozone (OOzone (O33))

In the stratosphere, ozone acts as a protective shield against In 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 the the atmosphere is present in the stratospherestratosphere

Peak concentration of 300 ppv occurs at an altitude of 25 km Peak concentration of 300 ppv occurs at an altitude of 25 km near equator & 15 km over polar regionsnear equator & 15 km over polar regions

It It absorbs absorbs approximately approximately 99%99% ultraviolet (UV) radiation ultraviolet (UV) radiation

Ozone Layer DepletionOzone Layer Depletion The ozone layer can be depleted by free radical catalysts, including The ozone layer can be depleted by free radical catalysts, including

nitric oxide (NO), nitrous oxide (Nnitric oxide (NO), nitrous oxide (N22O), hydroxyl (OH), atomic O), 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, the While there are natural sources for all of these species, the

concentrations of chlorine and bromine have increased markedly in concentrations of chlorine and bromine have increased markedly in recent years due to the release of large quantities of man-made recent years due to the release of large quantities of man-made organohalogen compounds, especially chlorofluorocarbons (CFCs) organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons and bromofluorocarbons

These highly stable compounds are capable of surviving the rise to These highly stable compounds are capable of surviving the rise to the stratosphere, where Cl and Br radicals are liberated by the the 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 reaction Each 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 by Ozone 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-depleting O) was the largest ozone-depleting

substance emitted through human activities.substance emitted through human activities.

Ozone Layer DepletionOzone Layer Depletion

Natural conditions prevailing in the stratosphere result in Natural conditions prevailing in the stratosphere result in a dynamic balance between the creation and destruction a dynamic balance between the creation and destruction of ozoneof ozoneMajor culprit in ozone depletion are ‘Freons’ QMajor culprit in ozone depletion are ‘Freons’ QWhen they wander upward in the stratosphere, following When they wander upward in the stratosphere, following reactions take place:reactions take place:

CFCF22ClCl22 + + hhv v →→ Cl* + CClF Cl* + CClF22**

yields chlorine atoms, and attack Oyields chlorine atoms, and attack O33::

Cl* + OCl* + O33 →→ ClO* + O ClO* + O22

ClO* + O ClO* + O →→ Cl* + O Cl* + O22

These two equations define a chemical cycle (catalytic These two equations define a chemical cycle (catalytic chain reaction) that can deplete ozonechain reaction) that can deplete ozone

Ozone Layer DepletionOzone Layer Depletion

Future of Ozone DepletionFuture of Ozone Depletion

If the manufacture, use, and emission of all ozone If the manufacture, use, and emission of all ozone depleting chemicals were to stop today the problem depleting chemicals were to stop today the problem wouldn’t not go away because millions of tons of those wouldn’t not go away because millions of tons of those persistent chemicals are now in the lower atmosphere persistent chemicals are now in the lower atmosphere working their way to the stratosphereworking their way to the stratosphere

Ozone Layer Depletion QOzone Layer Depletion Q

Environmental EffectsEnvironmental Effects

Serious potential environmental effects include Serious potential environmental effects include damage damage to Earth’s food chains on land & in the oceans and to Earth’s food chains on land & in the oceans and human health effects—increasing all types of skin human health effects—increasing all types of skin cancers and cataracts and suppression of immune cancers and cataracts and suppression of immune systemssystems

Ozone Layer Depletion QOzone Layer Depletion Q

Management Issues QManagement Issues Q

CollectionCollection & & ReuseReuseDevelop ways to collect and reuse CFCsDevelop ways to collect and reuse CFCsOne company in Germany recycles approximately One company in Germany recycles approximately 6000 refrigerators a month6000 refrigerators a month

SubstitutesSubstitutesTwo substitutes— Two substitutes— hydrofluorocarbonshydrofluorocarbons and and hydrochloro- fluorocarbons, hydrochloro- fluorocarbons, have advantageshave advantages HFCS do not contain chlorineHFCS do not contain chlorine Fluorine is 1000 times less efficient in causing ozone Fluorine is 1000 times less efficient in causing ozone depletiondepletion

Ozone Layer Depletion QOzone Layer Depletion Q

Injection of ChemicalsInjection of Chemicals

Propane will react with chlorine forming hydrochloric Propane 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 UV Learning to live with an increase in exposure to UV radiationradiation

Long-term achievement of sustainability require Long-term achievement of sustainability require management of anthropogenic Omanagement of anthropogenic O33-depleting chemicals-depleting chemicals

Thermal Inversion of AirThermal Inversion of Air

Although the temperature near the Earth’s surface Although the temperature near the Earth’s surface normally decreases with increasing altitude certain normally decreases with increasing altitude certain atmospheric condition can result in the opposite atmospheric condition can result in the opposite direction—direction—increasing temperature with increasing increasing 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 the temperature inversions result in air stagnation and the trapping of air pollutants in localized areastrapping of air pollutants in localized areas

Thermal Inversion

Picture showing the yellow haze from the thermal inversion

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