Key Findgs of the IPCC

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© Yann Arthus-Bertrand / Altitude

Key Findings of the IPCC WG1 AR5Key Findings of the IPCC WG1 AR5

Fredolin Tangang

IPCC WG1 Vice-Chair



IPCC WG1 AR5 Climate Change 2013: The

Physical Science Basis

• The IPCC has released its WG1

AR5 Climate Change 2013: ThePhysical Science Basis on 27 Sept

2013 in Stockholm S!eden

• The S"mmar# $or Polic#makers

%SP&' can (e do!nloaded $rom

the IPCC !e(site

http)**!!!+ipcc+ch and

!!!+climatechan,e2013+or,

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• IPCC) istorical perspecties role

$"nctions

• e# $indin,s (ased on o(serations

• 4etection and attri("tion

• "t"re climate pro6ections• S"mmar#

"tline



Inter-governmental Panel on Climate

Change (IPCC)

• IPCC plenar# comprises o$ all

co"ntries in the !orld

• IPCC 8"rea" comprises o$ 30

elected mem(ers !ith aria(le

n"m(ers $or each o$ the W&

re,ion9 IPCC elects its ("rea"mem(ers once in a :;7 #ears c#cle

• 3 !orkin, ,ro"ps a Task orce

on <GGI

• A"thors Contri("tors Reie!ers

Reie! =ditors



Inter-governmental Panel on Climate

Change (IPCC)



Why IPCC?• Prior to the establishment of IPCC, growing number of literatures

indicate the Earth’s climate system is warming due to increasingGHG concentration in atmosphere

• Independent, objective, fair and transparent assessment of the stateof global climate system is required

• or this reason .nited <ations General Assem(l# %.<GA' >2 proposed theesta(lishment o$ IPCC and in 1?@@ IPCC !as esta(lished "nder W& and

.<=P

• The IPCC provides such assessment and this becomes the sourceof information particularly to policy makers and UNFCCC on 1.Causes of climate change, 2. Potential impacts on built and natural

systems and socio-economic, 3. Possible response options.

• IPCC had published 5 assessment reports and various other reports.The latest is the IPCC Fifth Assessment Report (AR5), which wasreleased on Sept 27, 2013, in Stockholm, Sweden.



IPCC Reports

FAR 1990 SAR 1995 TAR 2001 AR4 2007 AR5 2013

IPCC had produced 5 Assessment Reports plus several otherspecial reports including the recently released SREX & SRREN.

SREX (2012)SRREN (2011)



How IPCC produces these reports?

Independentresearch,

Knowledge

generation,publication ofliteratures by

Scientificcommunity

IPCC doesn’t involveat this stage

IPCCAssessment

Process

IPCCAssessmentReport



IPCC Assessment Process

IPCC assessment is (ased on aaila(le

peer;reie!ed p"(lications



Key SPM Messages

19 Headlineson less than 2 Pages

10

2009:WGI Outline Approved

14 Chapters

Atlas of Regional Projections

54,677 Review Commentsby 1089 Experts

2010: 259 Authors Selected

Summary for Policymakers~14,000 Words



The Relatie Comprehensieness o$

IPCC WG1 AR5





Warming of the climate system is

unequivocal, and since the 1950s, many ofthe observed changes are unprecedented

over decades to millennia. The atmosphereand ocean have warmed, the amounts ofsnow and ice have diminished, sea level

has risen, and the concentrations ofgreenhouse gases have increased

Key Statement / Headline ofIPCC WG1 AR5 SPM



( I P C C

2 0 1 3

, F i g

. S P M

. 1 a

)

Each of the last three

decades has beensuccessively warmer at the

Earth’s surface than anypreceding decade since

1850.

In the NorthernHemisphere, 1983–2012

was likely the warmest 30-

year period of the last 1400years (medium confidence )



Warming in the climate system is unequivocal

( I P C C

2 0 1 3 ,

F i g

. S P M

. 1 b )

Over SEA increase

trend ~ 1.0oC percentury



Evidence from Paleoclimate Archives

I P C C

2 0 1 3

; F i g 5

. 7 a

)



( I P C C

2 0 1 3 ;

F i g

5 . 8

a )

Continental-scale surface temperature reconstructions show, with high confidence ,

multi- decadal periods during the Medieval Climate Anomaly (year 950 to 1250) thatwere in some regions as warm as in the late 20th century. These regional warm

periods did not occur as coherently across regions as the warming in the late 20th

century (high confidence )

Evidence from Paleoclimate Archives & Climate

Simulation



Temperature Ocean heat content

Sea Level Snow Cover

Glacier Arctic Sea-ice extent

( I P C C

2 0 1 3 .

F i g T S . 1

)



( I P C C

2 0 1

3 .

F i g S P M . 2

)

Wetter region gets morewetter and drier gets more

drier since the second halfof the 20th century

Extreme weather & climate

events became morefrequent



( I P C C

2 0 1

3 .

F i g T S . 3

)Glaciers and ice melting

has accelerated in

unprecedented speed inthe last decade



40% increase sincepre-industrial period

Ocean observed30% of theseemitted CO2

The atmospheric concentrations of carbon dioxide (CO2),methane (CH4), and nitrous oxide (N2O) have increased to

levels unprecedented in at least the last 800,000 years.

( I P C C

2 0 1

3 .

F i g S P M

. 4 a

)



Ocean became more acidic

( I P C C

2 0 1 3

. F i g S P M

. 4 b )



Contribution by Category to CO2

Emission

( I P C C

2 0 1

3 .

F i g T S . 4

)



• Except volcanic,changesgradual

• Anthro. fastersince ~1970,CO2 largestevery decade

since 1960s

• Time-averagednatural forcingsmall

( I P C

C

2 0 1 3 .

F i g 8 . 1 8

)







Earth has been in radiative imbalance,with more energy from the sun enteringthan exiting the top of the atmosphere,

since at least circa 1970. It is virtuallycertain that Earth has gained substantial

energy from 1971–2010.



Detection and Attribution

( I P C C

2 0 1

3 .

F i g 1 . 1

3 )



• Periods of little orno warming can

arise from internal

variability

• Internal variabilitycauses to a

substantial degreethe difference

between theobservations andthe simulations

(medium

confidence )

( I P C C

2 0 1

3 . B o x

T S . 3

F i g . 1

)



Natural + Anthropogenic Natural CO2 forcing only

Climate Models Responses to Various

Forcings

( I P C C

2 0 1

3 .

F i g T S . 9

)





Human influence on the

climate system is clear ( I P C C

2 0 1

3 .

F i g S P M . 6

)





Future Climate Projections

For future climateprojections, climate

models requires Emission

Scenarios. Models in AR5use Representative

Concentration Pathway(RCP)



RCP= RepresentativeConcentration Pathway

( I P C C

2 0 1

3 .

B o x T S . 6

)

Indicative Anthropogenic Radiative Forcing (RF)

for RCPs





The temperature increase during the last100 years was only about 0.8 o C.

Projected Global Average Temperature Change by end of21st Century

( I P C C

2 0 1 3 .

F i g S P M . 7 a )



The temperature increase during the last

100 years is only about 0.8 o C.

Projected Global Average Temperature Change by end of

21

st

Century

3-4oC projectedincrease overSoutheast Asia

region

( I P C C

2 0 1 3 .

F i g S P M . 8 a )



Projected Precipitation Change by end of

21st CenturySome regions will becomemore wetter and others

become more drier. Extremeprecipitation events over wet

tropical regions will very likelybecome more intense and more

frequent

( I P C C

2 0 1 3 .

F i g S P M . 8

b )



( I

P C C

2 0 1 3 .

F i g S P M . 8 c )Arctic will be

nearly ice-free by

the end of the 21st

century





Ocean will be

more acidic bythe end of the 21st

century ( I P C C

2 0 1 3 .

F i g T S . 2

0 b )



• There is high confidence

that ENSO will remainthe dominant mode ofinterannual variability inthe tropical Pacific, with

global effects in the 21stcentury.

• Due to the increase inmoisture availability,ENSO-relatedprecipitation variability

on regional scales willlikely intensify.

El Niño-Southern Oscillation(ENSO)



Global mean sea level will continue torise during the 21st century

( I P C C

2 0 1 3

, F

i g .

S P M

. 9 )



I P C C 2 0

1 3 F i g 1 3

. 2 0 b

0.4-0.6 mprojected SLRaround

Southeast Asiaregion



Limiting climate change will require substantial andsustained reductions of greenhouse gas emissions

( I P C C

2 0 1 3

, F

i g .

S P M

. 1 0 )

RCP2 6 would be the Emission Scenario to follow if we



RCP2.6 would be the Emission Scenario to follow if wewere to cap warming at 2oC



SUMMARY

• Warming of the climate system is unequivocal, and since the 1950s, many ofthe observed changes are unprecedented over decades to millennia.

• The atmosphere and ocean have warmed, the amounts of snow and ice havediminished, sea level has risen, and the concentrations of greenhousegases have increased

• Human influence on the climate system is clear

• Continued emissions of greenhouse gases will cause further warming andchanges in all components of the climate system.

• Global surface temperature change for the end of the 21st century is likelyto exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except

RCP2.6.

• Limiting climate change will require substantial and sustained reductions ofgreenhouse gas emissions



© Yann Arthus-Bertrand / Altitude

www.climatechange2013.orgwww.climatechange2013.orgFurther InformationFurther Information

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Key Findgs of the IPCC