global climate change -...

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?