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Globalclimatechange
1
⚈ Lectureoutline/goals:¡ Climatechange–abriefoverview¡ Someglobalindicators¡ Climatechangemi<ga<on
• poten<alforCarbonsequestra<oninforests
¡ Adap<ngtoclimatechange
Arrhenius,S.1896.Ontheinfluenceofcarbonicacidintheairuponthetemperatureoftheground.PhilosophicalMagazine41,237
⚈ IncreasedCO2intheairwillincreasegroundtemperatures
⚈ Strongerinfluencenearthepolesthanneartheequator
⚈ Strongerimpactinthenorthernhemisphere
⚈ Diminisheddifferenceintemperaturebetweendayandnight
IntergovernmentalPanelonClimateChange(IPCC)
⚈ Scien<ficbodycreatedin1988upontherequestofmembergovernments⚈ EndorsedbytheUnitedNa<ons⚈ Mission:
¡ providecomprehensivescien<ficassessmentsabouttheriskofclimatechangecausedbyhumanac<vity,itspoten<alconsequences,andpossibleop<onsforadap<ngtotheseconsequencesormi<ga<ngtheeffects
⚈ Voluntarycontribu<onsfromthousandsofscien<sts⚈ Interna<onallyacceptedauthorityonclimatechange⚈ Reliesonconsensus⚈ NobelPeacePrize2007⚈ See:h^p://www.ipcc.ch/
ChangesinatmosphericGHG’soverthepast20,000years
⚈ Thedebateisover…⚈ GHGconcentra<onsbeyond
rangeofnaturalvariability⚈ CO2=greatestradia<veforcing
CO2
200
240
280
320
360
400 Me
an pp
m
-2
-1
0
1
Radia
tive f
orcin
g (W
m-2)
CH4 Ra
diativ
e for
cing (
Wm-2
)
Mean
ppb
500
1000
1500
2000
-20000 -15000 -10000 -5000 0 Time (years bp)
-0.4
-0.2
0
0.2
0.4
N2O
Radia
tive f
orcin
g (W
m-2)
-20000 -15000 -10000 -5000 0 Time (years bp)
Mean
ppb 0
0.1
-0.1
-0.2
-0.3 200
250
300
From IPCC AR4 WG1 Tech Summary 2007
Range over past 650,000 years
HistoricCO2levels⚈ Fluctua<onsbetweenglacia<ons⚈ Currentlevelshighestinlast420,000yrs,possiblythelast20millionyrs⚈ Projectedlevels550–950ppmby2100
-450 -400 -350 -300 -250 -200 -150 -100 -50 0 50 150
200
250
300
350
400
Atmo
sphe
ric C
O 2 (pp
mV)
Thousands of years
1970 1980 1990 2000 1960 310
320
330
340
350
360
Atmo
sphe
ric C
O 2 Co
ncen
tratio
n (pp
m)
Human perturbation
From IPCC AR4 WG1 Tech Summary 2007
Globallandsurfacetemperaturechanges
⚈ Closeagreementbetweenobserva<onsandmodelsincorpora<ngnaturalandhumanforcing
⚈ Noapparenttemperatureincreasewithouthumaninputs
1900 1920 1940 1960 1980 2000 Year
0
0.5
1.0
Temp
eratu
re an
omaly
(°C)
Observed mean temp by decade
Models using only natural forcings (i.e. solar activity and volcanoes)
Models using natural and anthropogenic forcings
From IPCC AR5 WG1 Tech Summary 2013
From IPCC AR5, 2013
⚈ Previous10yearswerethewarmestyearsintheinstrumentalrecord(since1850)ofglobalsurfacetemperature
Globalclimatechangeindicators:polaricecaps
Globalclimatechangeindicators:glaciersandsnowcover
⚈ Decliningsnowcover⚈ Widespreadretreatofglaciersinbothhemispheres
Grinnell Glacier, Glacier National Park, USA 1938 – 2005
1938 1981 1998 2005
Globalclimatechangeindicators:risingsealevel
⚈ Globalaveragesealevelrisefrom1961-2003=1.8mm/yr(3.1mm/yrfrom1993-2003)
⚈ Sources=thermalexpansion,glaciersandicecaps,GreenlandIceSheet,Antarc<cIceSheet⚈ ManyPacificislandsthreatened
Global average sea level
1850 1900 1950 2000 Year
Diffe
renc
e fro
m 19
61-1
990 (
mm)
-150
-100
-50
0
50
From IPCC AR5 WG1 Tech Summary 2013
Globalclimatechangeindicators:extremeweatherevents⚈ IPCCAR4WGII2007,“…confidencehasincreasedthatsomeweathereventsand
extremeswillbecomemorefrequent,morewidespreadand/ormoreintenseduringthe21stcentury…”
Drought
Floods
Heat waves
Precipitation Cyclones/storms
July 31, 2003
Warmingscenariosforfutureprojec<onsIPCCFilhAssessmentReport(AR5)2013
⚈ Representa<veConcentra<onPathways(RCPs)¡ RCP2.6–decliningCO2
¡ RCP4.5–peakCO2in2040,declinetherealer¡ RCP6–stableCO2by2100¡ RCP8.5–con<nuedrisingCO2
0.0
-1.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0 D
epar
ture
s (°
C) f
rom
the
1961
-199
0 av
erag
e Northern hemisphere
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Year
Variations in the Earth’s surface temperature – past, present…
Instrumental data (AD 1902-1999) Reconstruction (AD 1000-1980) Reconstruction (40-year smoothed)
From IPCC TAR 2001
Global
2100
Scenario models envelope
Range from scenario models
5.8°
1.4°
future
Projec<onsoffuturecondi<ons1986-2005versus2081-2100
From IPCC AR5 WG1 Tech Summary 2013
Average temperature
Average precipitation
Average sea level
RCP 2.6 RCP 8.5
Forests/forestryversusclimatechange
Climatechangemi<ga<on:forestry
⚈ Lessthanhalfofhumanemissionsstayinatmosphere
3.2 ± 0.1 GtC/yr Airborne fraction
Atmosphere
Biosphere
6.4 ± 0.4 Fossil fuel
2.2 ± 0.4 Ocean uptake
1.6 ± 0.9 Land-use change
2.6 ± 0.1 Land uptake
(esp. forests)
Data from IPCC AR4 WG1 2007
Reduce emissions Increase sinks
⚈ Mitigation = reduced emissions and/or increased sinks
⚈ Forests/forestry can have significant impacts on future CO2 concentrations
Forestsandcarbon
⚈ Globalfossilcarbonemissions~7Gt/yr⚈ Equivalentto:
o 28billionm3ofwood(28,000×Gudrun)o halfofthebiomassCinCanada’smanagedforest
Sweden:cycloneGudrun(2005)
⚈ ForestsandforestrycannotsolvetheproblemoffossilCemissions,buttheycancontributetothesolu<on
⚈ Reduceddeforesta<on,increasedafforesta<oncouldmorethanoffsetglobalcarbonemissionsfromthetransporta<onsector(Stern2006)
Forestsandmi<ga<on
Mi<ga<onop<onsintheforestsector
⚈ Increase(ormaintain)forestarea
⚈ Increasecarbondensity
⚈ IncreasestoredCinproducts
⚈ Reducefossilemissionsthroughproductsubs<tu<onandbioenergy
Warmingwillcon<nueevenwithmi<ga<on
⚈ Con<nuedwarmingevenwithemissionsheldat2000levels
⚈ Adapta<onisrequired
From IPCC AR4 WG1 Tech Summary 2007
1st assessment report 2nd assessment report 3rd assessment report Observed
Constant from 2000
Emissions scenarios
BC’sadapta<onstrategy:preparingforclimatechange(see:www.env.gov.bc.ca/cas/adapta<on/)
⚈ Strategy1:Buildastrongfounda<onofknowledge¡ Engageclimatescience¡ Buildrobustobserva<onnetworks¡ Developadapta<onplanningtools¡ Knowledgetransferandoutreachac<vi<es
⚈ Strategy2:Makeadapta<onpartofgov’tbusiness¡ Consideradapta<oninplanning¡ Implementthroughacoordinatedapproach
⚈ Strategy3:Assessrisksandimplementpriorityadapta<onac<onsinsectors¡ Assessrisksandimplementac<ons
Ques<onstoreview:
⚈ WhatistheIPCC,andwhatisitsmission?⚈ Whatarethethreemaingreenhousegases,andwhich
causesthemostwarming?⚈ Name3indicatorsofglobalclimatechange.⚈ Give3waysthattheforestsectorcanhelpmi<gate
climatechange.⚈ Whatarethe3strategiescurrentlyemployedbytheBC
governmenttoadapttoclimatechange?