ClimateClimate

OverviewOverviewClimate Components and ControlsClimate Components and ControlsClimate Classification and Global Climate Classification and Global PatternsPatternsClimate RegionsClimate Regions

TropicalTropicalMesothermalMesothermalMicrothermalMicrothermalPolar ClimatesPolar ClimatesDry and SemiDry and Semi--AridAridHighlandHighland

Climate ChangeClimate Change

Climate and Climate ComponentsClimate and Climate ComponentsClimatology: Studying long term weather patterns in Climatology: Studying long term weather patterns in order to identify areas of similar characteristicsorder to identify areas of similar characteristics

More recently, it has become focused on climate changeMore recently, it has become focused on climate change

Climate Regions: areas of the Earth that exhibit Climate Regions: areas of the Earth that exhibit similar climatic characteristicssimilar climatic characteristics

Characteristic biomes: forests, savanna, grasslands, Characteristic biomes: forests, savanna, grasslands, desert, and tundradesert, and tundra

Components of ClimateComponents of ClimateInsolationInsolation: Varies with latitude, : Varies with latitude, daylengthdaylengthTemperature: Varies with latitude, altitude, continentalTemperature: Varies with latitude, altitude, continental--maritime effects, pressure systems, air massesmaritime effects, pressure systems, air massesAir masses: Varies with maritime/continental surfaces, Air masses: Varies with maritime/continental surfaces, latitudelatitudeMoisture: varies with temperature, pressure systems, Moisture: varies with temperature, pressure systems, continental/maritime surfacescontinental/maritime surfaces

ClassificationClassificationClassification systemsClassification systems

Empirical classificationEmpirical classificationuses statistical data to classifyuses statistical data to classify

Genetic classificationGenetic classificationuses causal factors to classifyuses causal factors to classify

Boundaries between climate regionsBoundaries between climate regionsAre transition zones, not abrupt changesAre transition zones, not abrupt changesShift over timeShift over time

With climate change, climate regions are With climate change, climate regions are expected to shift expected to shift polewardpoleward between 150between 150--550 550 kmkm

Example: Tropical Monsoon Example: Tropical Monsoon climatesclimates

Empirical classificationEmpirical classificationhigh temperatures with high temperatures with little annual variationlittle annual variationOver 6 cm of rainfall Over 6 cm of rainfall for 9 for 9 –– 11 months of 11 months of the year the year Less than 6 cm of Less than 6 cm of rainfall for 1 rainfall for 1 --3 months 3 months of the yearof the year

Genetic classificationGenetic classificationThe ITCZ influences the The ITCZ influences the onshore flow of warm, onshore flow of warm, moist air, producing moist air, producing heavy rainfall during heavy rainfall during the summer monthsthe summer monthsSubtropical Highs Subtropical Highs forming over forming over continental masses continental masses create a dry offshore create a dry offshore flow during the winter flow during the winter monthsmonths

KKööppenppen--Geiger Climate Classification System (Empirical)Geiger Climate Classification System (Empirical)Uses Average monthly temperatures, average monthly rainfall, andUses Average monthly temperatures, average monthly rainfall, and total annual total annual rainfall for classification to distinguish arid areasrainfall for classification to distinguish arid areas

An Empirical Classification SystemAn Empirical Classification System

Some Genetic GeneralizationsSome Genetic GeneralizationsMonthly average temperatures decrease Monthly average temperatures decrease with increasing latitudewith increasing latitudeannual range increases with increasing annual range increases with increasing latitude latitude Where a single pressure system Where a single pressure system dominates, rainfall patterns are dominates, rainfall patterns are convectional (highest monthly rainfall convectional (highest monthly rainfall averages correspond to highest monthly averages correspond to highest monthly average temperatures average temperatures –– i.e. summer)i.e. summer)

ITCZITCZPolar High PressurePolar High Pressure

Where the subtropical highs are present, Where the subtropical highs are present, effects on weather are variable, depending effects on weather are variable, depending on whether they are motivating maritime on whether they are motivating maritime or continental air massesor continental air masses

Continental air masses create arid conditionsContinental air masses create arid conditionsMaritime air masses create moist conditionMaritime air masses create moist condition

In mid latitudes where cyclonic systems are In mid latitudes where cyclonic systems are present, rainfall patterns follow the shift of present, rainfall patterns follow the shift of the storm tracksthe storm tracksContinental and Maritime influencesContinental and Maritime influences

Greatest between Northern (more continental) Greatest between Northern (more continental) and Southern Hemispheres (more maritime)and Southern Hemispheres (more maritime)

Greater between Asia (continental winter Greater between Asia (continental winter influences) than North America (maritime and influences) than North America (maritime and continental influences during the winter)continental influences during the winter)

Tropical ClimatesTropical ClimatesGeneral Characteristics (A)General Characteristics (A)

Lie between Tropics of Capricorn and CancerLie between Tropics of Capricorn and CancerLargest climate region on EarthLargest climate region on EarthGenetic factorsGenetic factors

High High InsolationInsolation: even day length and near vertical sun rays year: even day length and near vertical sun rays year--roundroundITCZ exerts a great influence for part or all of the year, bringITCZ exerts a great influence for part or all of the year, bringing high ing high rainfallrainfallUnstable maritime air massesUnstable maritime air masses

Empirical factorsEmpirical factorsAverage temperature of each month above 18Average temperature of each month above 18ooCCLittle range in annual temperatures Little range in annual temperatures High total annual rainfall, although monthly averages can varyHigh total annual rainfall, although monthly averages can vary

SubcategoriesSubcategoriesTropical Rainforest (Tropical Rainforest (AfAf))Tropical Monsoon (Am)Tropical Monsoon (Am)Tropical Savanna (Aw)Tropical Savanna (Aw)

Tropical Rainforest (Tropical Rainforest (AfAf))ITCZ is present throughout the entire yearITCZ is present throughout the entire yearHigh monthly average rainfall throughout High monthly average rainfall throughout the year the year –– Monthly average > 6 cmMonthly average > 6 cmAverage monthly temperatures are fairly Average monthly temperatures are fairly high, with a small annual rangehigh, with a small annual rangeEcosystemEcosystem

Broadleaf rainforestBroadleaf rainforestNutrient poor soils Nutrient poor soils

nutrients stored in the vegetation itselfnutrients stored in the vegetation itselfbasis of basis of swiddenswidden ((““slash and burnslash and burn””) agriculture) agriculture

Tropical Monsoon (Am)Tropical Monsoon (Am)Feature a distinct wet season and dry seasonFeature a distinct wet season and dry season

Significant rainfall for 9Significant rainfall for 9--12 months of the year ( > 6cm)12 months of the year ( > 6cm)ITCZ brings rain from the moist onshore flow of windsITCZ brings rain from the moist onshore flow of winds

wet summerswet summersContinental subtropical highs create dry seasons through the Continental subtropical highs create dry seasons through the dry offshore flow of windsdry offshore flow of winds

dry winters dry winters Monthly average rainfall < 6 cm for 1 Monthly average rainfall < 6 cm for 1 --3 months per year3 months per year

Very high amount of rainfall during wet seasonVery high amount of rainfall during wet seasonFairly high average monthly temperatures with a small Fairly high average monthly temperatures with a small annual rangeannual rangeEcosystemEcosystem

Broadleaf rainforest grading to thorn scrub on margins with Broadleaf rainforest grading to thorn scrub on margins with tropical savannatropical savannaSoils are nutrient poor, similar to those of the Tropical Soils are nutrient poor, similar to those of the Tropical Rainforest climateRainforest climate

Tropical Savanna (Aw)Tropical Savanna (Aw)Lie Lie polewardpoleward of Tropical Rainforest and of Tropical Rainforest and Monsoon climatesMonsoon climatesFeatures a distinct wet and dry seasonFeatures a distinct wet and dry season

ITCZ affects these areas for less than six ITCZ affects these areas for less than six months of the yearmonths of the year

wet summers wet summers Average Monthly precipitation > 6 cm for 6 Average Monthly precipitation > 6 cm for 6 –– 9 9 months months

Subtropical highs create dry conditions during Subtropical highs create dry conditions during the rest of the yearthe rest of the year

dry wintersdry wintersAverage monthly rainfall < 6 cm for 3 Average monthly rainfall < 6 cm for 3 –– 6 months6 monthsmoisture budget deficit during this timemoisture budget deficit during this time

Ecosystem: Savanna (grasslands)Ecosystem: Savanna (grasslands)

MesothermalMesothermal ClimatesClimatesGeneral Characteristics (C)General Characteristics (C)

Mild MidMild Mid--latitude climateslatitude climatesLow midLow mid--latitudeslatitudesVariable weather patternsVariable weather patterns

continental and maritime air masses brought into conflict from continental and maritime air masses brought into conflict from shifting pressure systems (e.g., shifting pressure systems (e.g., midlatitudemidlatitude wave cyclones during wave cyclones during the winter)the winter)Ocean currents exert strong influence on air massesOcean currents exert strong influence on air masses

East coast currents are warm and strengthen East coast currents are warm and strengthen airmassesairmassesWest coast currents are cold and weaken air massesWest coast currents are cold and weaken air masses

Summers cool with higher latitude (warm Summers cool with higher latitude (warm –– cool)cool)Summers are humid except Summers are humid except underunder subtropical highs subtropical highs Monthly average temperatures are above freezingMonthly average temperatures are above freezing

Monthly average temperature for coldest month between 18 Monthly average temperature for coldest month between 18 ooCC and and --3 3 ooCCMonthly average temperature for warmest month above 10 Monthly average temperature for warmest month above 10 ooCC

Annual temperature range from 5 Annual temperature range from 5 –– 20 20 ooCC

SubcategoriesSubcategoriesHumid Subtropical Climates Humid Subtropical Climates

CfaCfaCwaCwaCwbCwb

Marine West Coast ClimatesMarine West Coast ClimatesCfbCfbCfcCfc

Mediterranean ClimatesMediterranean ClimatesCsaCsaCsbCsb

Humid SubtropicalHumid SubtropicalOccur on the East coast of continents, just Occur on the East coast of continents, just polewardpoleward of the tropicsof the tropicsHumid subtropical Humid subtropical –– hot summer pattern (hot summer pattern (CfaCfa))

Winter weather patterns dominated by Winter weather patterns dominated by midlatitudemidlatitudecyclonic storm tracks which bring precipitationcyclonic storm tracks which bring precipitation

winter storm tracks follow routes at lower latitudeswinter storm tracks follow routes at lower latitudesSummer patterns dominated by subtropical highs which Summer patterns dominated by subtropical highs which bring bring mTmT air masses over the continentsair masses over the continents

Heating by warm ocean currents create instability and Heating by warm ocean currents create instability and precipitationprecipitation

Rainfall occurs yearRainfall occurs year--roundround

Humid subtropical Humid subtropical -- winter dry pattern (winter dry pattern (CwaCwa, , CwbCwb))Mainly in Asia Mainly in Asia –– ““temperate monsoonstemperate monsoons””: wet: wet--dry dry seasonsseasons

ITCZ brings rainfall during the summerITCZ brings rainfall during the summerLess rainfall during the winter (subtropical highs)Less rainfall during the winter (subtropical highs)Wettest summer month has 10 times the precipitation of Wettest summer month has 10 times the precipitation of driest winter monthdriest winter month

Marine West Coast (Marine West Coast (CfbCfb, Cfc), Cfc)Occur on West coast of continentsOccur on West coast of continentsMild winters, cool summersMild winters, cool summersmPmP air masses dominateair masses dominateCyclonic storm systems occur throughout the yearCyclonic storm systems occur throughout the year

rainfall occurs yearrainfall occurs year--roundround

In Western Hemisphere, mountains along the In Western Hemisphere, mountains along the West Coast restrict the extent of this climate West Coast restrict the extent of this climate region (rain shadow effect)region (rain shadow effect)Exception: AppalachiansException: Appalachians

Elevation moderates summer temperaturesElevation moderates summer temperaturesCyclonic storms bring rainfall during the winter and Cyclonic storms bring rainfall during the winter and rainfall is enhanced in the summer due to convectional rainfall is enhanced in the summer due to convectional heating and cooling and heating and cooling and orographicorographic effects as well.effects as well.

Mediterranean (Mediterranean (CsaCsa, , CsbCsb))Characterized by a distinct wetCharacterized by a distinct wet--dry dry seasonal patternseasonal pattern

winterwinter--wet, summerwet, summer--drydryWettest winter month has at least 3 times the Wettest winter month has at least 3 times the precipitation as the warmest summer monthprecipitation as the warmest summer month

Dominated by Subtropical HighsDominated by Subtropical HighsContinental (dry) air masses in the summerContinental (dry) air masses in the summerCyclonic storm tracks in the winter (wet)Cyclonic storm tracks in the winter (wet)

Moisture deficits in the summerMoisture deficits in the summervegetation adapted to these conditionsvegetation adapted to these conditions

hard, waxy leaves retain moisturehard, waxy leaves retain moisturechaparral, chaparral, maquismaquis, , mattoralmattoral, , malleemallee scrubscrub

MicrothermalMicrothermal ClimatesClimatesGeneral characteristics (D)General characteristics (D)High midHigh mid--latitude climates with severe winterslatitude climates with severe winters

Increasing seasonality: greater variability in day length Increasing seasonality: greater variability in day length and temperature rangeand temperature rangePolar high pressure and subtropical lows are the main Polar high pressure and subtropical lows are the main motivators of air masses (motivators of air masses (cPcP, , mPmP))

Rainfall follows convectional patternsRainfall follows convectional patternsAt lowest latitudes of this region, cyclonic storm tracks At lowest latitudes of this region, cyclonic storm tracks influence rainfall patternsinfluence rainfall patternsContinental effects create dry winter conditions in AsiaContinental effects create dry winter conditions in Asia

Average monthly temperatures decrease with Average monthly temperatures decrease with increasing latitudeincreasing latitude

1 1 –– 7 months with average below freezing7 months with average below freezingWarmest month above 10 Warmest month above 10 ooCC, coldest month below , coldest month below --3 3 ooCC

Annual range of temperatures increases dramatically Annual range of temperatures increases dramatically with increasing latitudewith increasing latitude

20 20 –– 65 65 ooCC differences possibledifferences possible

SubcategoriesSubcategoriesHumid continental hotHumid continental hot--summer climatessummer climates

DfaDfaDwaDwa

Humid continental mildHumid continental mild--summer climatessummer climatesDfbDfbDwbDwb

Subarctic climatesSubarctic climatesDfcDfcDfdDfdDwcDwcDwdDwd

Humid Continental HotHumid Continental Hot--Summer (Summer (DfaDfa))Few months with monthly average Few months with monthly average temperatures below freezingtemperatures below freezingNorth AmericaNorth America

Cyclonic storm tracks from interaction of Cyclonic storm tracks from interaction of mTmTand and cPcP air masses provide precipitation yearair masses provide precipitation year--round, sustained in the summer by round, sustained in the summer by convectional rainfall as wellconvectional rainfall as well

Asia (Asia (DwaDwa))Winters dominated by strong dry Winters dominated by strong dry cPcP air mass, air mass, producing monsoonal rain patternsproducing monsoonal rain patterns

VegetationVegetationForests (where precipitation is high)Forests (where precipitation is high)Grasslands (where precipitation is low)Grasslands (where precipitation is low)

Humid Continental MildHumid Continental Mild--Summer Summer Climates Climates DfbDfb))

Roughly half the year experiences average Roughly half the year experiences average monthly temperatures below freezingmonthly temperatures below freezingWeather patterns dominated by Weather patterns dominated by cPcP air air massmass

Rainfall follows a convectional patternRainfall follows a convectional patternSummers wetter than wintersSummers wetter than winters

Dry winters more pronounced in Asia (Dry winters more pronounced in Asia (DwbDwb))Spring melt of winter snows provides additional Spring melt of winter snows provides additional moisture inputmoisture input

Thin soils with moderate fertilityThin soils with moderate fertility

Subarctic Climates (Subarctic Climates (DfcDfc, , DfdDfd, , DwcDwc, , DwdDwd))

Over half the year experiences average Over half the year experiences average monthly temperatures below freezingmonthly temperatures below freezingSummers are cool and winters harshSummers are cool and winters harsh

Extremely high range of temperaturesExtremely high range of temperatures

Weather patterns are dominated by Weather patterns are dominated by cPcP air air massmass

Rainfall follows a convectional pattern (highest Rainfall follows a convectional pattern (highest in the summer)in the summer)Low total annual precipitationLow total annual precipitation

Ecosystem featuresEcosystem featuresBoreal forests (taiga forest)Boreal forests (taiga forest)permafrost (soils frozen beneath the surface permafrost (soils frozen beneath the surface year round)year round)

Polar ClimatesPolar ClimatesGeneral characteristics (E)General characteristics (E)

Above 66.5Above 66.5oo N/S LatitudeN/S LatitudeLow levels of Low levels of insolationinsolation

Low sun angle all yearLow sun angle all yearHigh High albedoalbedo of snow and iceof snow and ice

Extreme variation in day lengthExtreme variation in day length

Dominated by Polar High Pressure systemsDominated by Polar High Pressure systemsLow humidity, little precipitationLow humidity, little precipitation

No true summerNo true summer

SubcategoriesSubcategoriesTundra (ET)Tundra (ET)Ice Caps/Sheets (EF)Ice Caps/Sheets (EF)Polar MarinePolar Marine

Tundra Climate (ET)Tundra Climate (ET)Average monthly temperatures below Average monthly temperatures below freezing with continuous snow cover for 8 freezing with continuous snow cover for 8 –– 10 months each year10 months each yearMaximum summer temperature no more Maximum summer temperature no more than 10than 10ooCCShort burst of vegetation when snow meltsShort burst of vegetation when snow melts

lichen, moss, sedges, some flowering plants, no lichen, moss, sedges, some flowering plants, no treestreesPermafrostPermafrost

Ice Cap/Ice Sheet Climate (EF)Ice Cap/Ice Sheet Climate (EF)All monthly average temperatures below All monthly average temperatures below freezingfreezing

--7878ooC has been recorded in AntarcticaC has been recorded in Antarctica

Polar high pressure systemPolar high pressure systemCold, dry air, little precipitationCold, dry air, little precipitationIce has accumulated for hundreds of Ice has accumulated for hundreds of thousands of yearsthousands of years

900,000 years maximum age recorded in an ice 900,000 years maximum age recorded in an ice corecore

dissolved gases in the ice give a profile of changes to dissolved gases in the ice give a profile of changes to EarthEarth’’s atmospheric composition.s atmospheric composition.

Ice sheets can be several kilometers thickIce sheets can be several kilometers thick

Polar Marine ClimatePolar Marine ClimateOceans moderate temperaturesOceans moderate temperatures

--77ooC is maximum lowC is maximum lowColder than Tundra Climates on average Colder than Tundra Climates on average

Small annual temperature range (no more than Small annual temperature range (no more than 1515ooC)C)

More precipitation than other Polar More precipitation than other Polar climatesclimates

sleetsleet

Predominant in coastal areas at the Predominant in coastal areas at the southern extreme of the Polar rangesouthern extreme of the Polar range

Arid and Semiarid ClimatesArid and Semiarid ClimatesGeneral Characteristics (B)General Characteristics (B)

Climate Region defined by Climate Region defined by permanent moisture deficitspermanent moisture deficitsThe potential demand for water exceeds its availability The potential demand for water exceeds its availability throughout the entire yearthroughout the entire year

Deserts: Available moisture is less than half of demandDeserts: Available moisture is less than half of demandSteppe: Available moisture is greater than half, but less than Steppe: Available moisture is greater than half, but less than the the total demandtotal demand

Genetic factorsGenetic factorsSubtropical highs dominateSubtropical highs dominateContinental effect dominatesContinental effect dominates

AsiaAsia

Rain shadowsRain shadows

VegetationVegetationXerophytes: plants adapted to retain moisture, such as cactiXerophytes: plants adapted to retain moisture, such as cactiPhreatophytesPhreatophytes: plants with roots that penetrate deep down to : plants with roots that penetrate deep down to where the water iswhere the water is

SubgroupsSubgroupsLow Latitude Hot Desert Climates Low Latitude Hot Desert Climates

BWhBWh

MidlatitudeMidlatitude Cold Desert ClimatesCold Desert ClimatesBwkBwk

Low Latitude Hot Steppe ClimatesLow Latitude Hot Steppe ClimatesBShBSh

MidlatitudeMidlatitude Cold Steppe ClimatesCold Steppe ClimatesBSkBSk

Low Latitude Hot Desert Climates Low Latitude Hot Desert Climates ((BWhBWh))

Tropical and SubtropicalTropical and SubtropicalHigh temperatures (Average annual High temperatures (Average annual temperature above 18temperature above 18ooC)C)0 0 –– 38 cm rainfall annually38 cm rainfall annuallyDominated by Subtropical Highs, Dominated by Subtropical Highs, Continental EffectContinental Effect

Typically occur on western edges of continents, Typically occur on western edges of continents, but desert conditions extend across North but desert conditions extend across North Africa into Saudi ArabiaAfrica into Saudi Arabia

When the subtropical highs depart, instead of moist When the subtropical highs depart, instead of moist wind being brought in from the east, dry wind off the wind being brought in from the east, dry wind off the Asian steppes and deserts is brought in insteadAsian steppes and deserts is brought in instead

Rainfall follows a convectional patternRainfall follows a convectional pattern

ITCZ?

MidlatitudeMidlatitude Cold Desert Climate (Cold Desert Climate (BWkBWk))Occur at higher latitudes and elevations Occur at higher latitudes and elevations than hot desertsthan hot desertsAverage precipitation is below 25cm Average precipitation is below 25cm annuallyannuallyAverage annual temperature is below 18 Average annual temperature is below 18 ooCCRainfall comes with convectional patterns Rainfall comes with convectional patterns and and midlatitudemidlatitude cyclonic storm systemscyclonic storm systemsLocationsLocations

Southwest US into NevadaSouthwest US into NevadaAsia (Gobi Desert and Mongolia)Asia (Gobi Desert and Mongolia)Patagonian Desert in ArgentinaPatagonian Desert in Argentina

LowLow--Latitude Hot Steppe Climates (Latitude Hot Steppe Climates (BShBSh))Occur on the margins of hot deserts where Occur on the margins of hot deserts where precipitation is a little higherprecipitation is a little higher

Average annual precipitation is between 38 Average annual precipitation is between 38 –– 76 cm76 cm

Convectional rainfall patternConvectional rainfall patternAverage annual temperature is above 18 Average annual temperature is above 18 ooCC

MidlatitudeMidlatitude Cold Steppe Climate (Cold Steppe Climate (BSkBSk))Occur on the Occur on the polewardpoleward margins of cold desertsmargins of cold deserts25 25 –– 64 cm of precipitation per year64 cm of precipitation per yearPrecipitation is both convectional and cyclonic Precipitation is both convectional and cyclonic in originin originAverage annual temperature is below 18 Average annual temperature is below 18 ooCC

Highland ClimatesHighland ClimatesNot one single climate, but a gradual Not one single climate, but a gradual gradation of climate types as one gradation of climate types as one moves up a mountain slopemoves up a mountain slope

Increases in altitude correspond to Increases in altitude correspond to increases in longitudeincreases in longitudeVegetation changes correspondinglyVegetation changes correspondingly

OrographicOrographic rainfall plays a crucial role in rainfall plays a crucial role in the climatethe climate

Wet/dry climate conditions with rain Wet/dry climate conditions with rain shadow effectshadow effect

MountainMountain--Valley breezes are important Valley breezes are important regulators of temperatureregulators of temperature

A B

C

D

E

Global Climate ChangeGlobal Climate ChangeEvidenceEvidence

Global average temperatures since 1998 have Global average temperatures since 1998 have been the highest on record been the highest on record Rate of increase of temperatures is highest on Rate of increase of temperatures is highest on recordrecordWithin 1Within 1ooC of meeting the highest temperatures of C of meeting the highest temperatures of the last 125,000 years (which are the highest on the last 125,000 years (which are the highest on record over the last 440,000 years)record over the last 440,000 years)Concentration of COConcentration of CO22 is the highest over the last is the highest over the last 440,000 years440,000 years

Challenge: what warming effects are Challenge: what warming effects are anthropogenic forcing, and which are natural anthropogenic forcing, and which are natural forcing?forcing?

Data sourcesData sourcesContemporary climatologyContemporary climatology

Direct atmospheric monitoringDirect atmospheric monitoring

PaleoclimatologyPaleoclimatologyIce coresIce coresTreeTree--ring densityring densitySedimentsSedimentsCoral reefsCoral reefsPollenPollen

CausesCausesGreenhouse gasesGreenhouse gases

9090--99% certainty that global warming is f99% certainty that global warming is frorom the buildm the build--up up greenhouse gasesgreenhouse gasesCarbon dioxide (COCarbon dioxide (CO22))

Accounts for 64% of warmingAccounts for 64% of warming33% increase over pre33% increase over pre--industrial levelsindustrial levelsAttributed to the burning of fossil fuels and net loss of forestAttributed to the burning of fossil fuels and net loss of forest

Methane (CHMethane (CH44))Accounts for 19% of warmingAccounts for 19% of warmingover 100% increase over preover 100% increase over pre--industrial levelsindustrial levelsAttributed to anaerobic oxidation of organic compoundsAttributed to anaerobic oxidation of organic compounds

50% from livestock digestion and organic processes in rice 50% from livestock digestion and organic processes in rice fieldsfieldsNitrous oxide (NNitrous oxide (N22O)O)

Up 17% over preUp 17% over pre--industrial periodindustrial periodAttributed to fertilizer use Attributed to fertilizer use –– with some uncertaintywith some uncertainty

Halocarbons (CFCs)Halocarbons (CFCs)Absorb a different wavelength of infrared radiation than carbon Absorb a different wavelength of infrared radiation than carbon dioxidedioxidereduction in stratospheric ozone creates more surface warmingreduction in stratospheric ozone creates more surface warming

Directly attributable to human activityDirectly attributable to human activity

Predicted changesPredicted changesBased on General Circulation ModelsBased on General Circulation ModelsThree scenarios (1990Three scenarios (1990--2100)2100)

Low Forecast Low Forecast –– 1.41.4ooCCMiddle Forecast Middle Forecast –– 3.63.6ooCCHigh Forecast High Forecast –– 5.85.8ooCC

The Arctic is warming at a rate greater The Arctic is warming at a rate greater than that predicted by the high forecastthan that predicted by the high forecast

Effects of global warmingEffects of global warmingDroughts that threaten food supplyDroughts that threaten food supply

crops very sensitive to climatic conditionscrops very sensitive to climatic conditions

Shifting climatic regionsShifting climatic regionsspecies redistributionspecies redistributionPolar species especially are at riskPolar species especially are at risk

Melting of ice sheets/caps and glaciersMelting of ice sheets/caps and glaciers11% of Antarctica is composed of ice shelves11% of Antarctica is composed of ice shelves8000 km8000 km22 have disintegrated since 1993have disintegrated since 1993

Changes in sea levelChanges in sea levelLow forecast Low forecast –– 0.09 m 0.09 m Medium forecast Medium forecast –– 0.48 m 0.48 m High forecast High forecast –– 0.88 m 0.88 m 25% in rise attributable to thermal expansion of water25% in rise attributable to thermal expansion of water

Kyoto ProtocolKyoto ProtocolCalls for an overall reduction in carbon Calls for an overall reduction in carbon dioxide levels of 5.2% (1990 levels) dioxide levels of 5.2% (1990 levels) between 2008between 2008--20122012

Some countries favor a 15% reduction by 2010Some countries favor a 15% reduction by 2010

Individual country contributionsIndividual country contributionsEuropean Union European Union –– 8%8%Australia Australia –– 8%8%Canada Canada –– 6%6%USA USA –– 7%, but never ratified the treaty and 7%, but never ratified the treaty and withdrew from the process in 2001withdrew from the process in 2001