© Yann Arthus-Bertrand / Altitude
An Overview of the Fifth Assessment Report of the IPCC WG1
An Overview of the Fifth Assessment Report of the IPCC WG1
Masahide KimotoAtmosphere and Ocean Research Institute
The University of Tokyo LA, Ch 11, IPCC AR5 WG1
Key SPM Messages
19 Headlineson less than 2 Pages
22009: WGI Outline Approved
14 ChaptersAtlas of Regional Projections
54,677 Review Commentsby 1089 Experts
2010: 259 Authors Selected
Summary for Policymakers~14,000 Words
Limiting climate change will require substantial and sustained reductions of
greenhouse gas emissions
Limiting climate change will require substantial and sustained reductions of
greenhouse gas emissions
Warming in the climate systemis unequivocal
Warming in the climate systemis unequivocal
Human influence on theclimate system is clearHuman influence on theclimate system is clear
Key Findings
Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.
In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years (medium confidence).
(IPCC 2013, Fig. SPM.1)
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.
It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010, and it likely warmed between
the 1870s and 1971. It is likely that the ocean warmed between 700 and 2000 m from 1957 to 2009.
The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels
unprecedented in at least the last 800,000 years.(They) have all increased since 1750 due to human activity.
(IPC
C 2
013,
Fig
. SP
M.5
)
Total radiative forcing is positive, […]. The largest contribution to total radiative forcing is caused by the increase in the
atmospheric concentration of CO2 since 1750.
Human influence on the climate system is clear.
(IPC
C 2
013,
Fig
. SP
M.6
)
Human influence on the climate system is clear.
(IPC
C 2
013,
Fig
. SP
M.6
)
Representative Concentration Pathways (RCP)
RCP8.5
RCP6.0
RCP4.5
RCP2.6
Global surface temperature change for
the end of the 21st century is likely to
exceed 1.5 ⁰C relative to 1850 for all scenarios
except RCP2.6.
(IPCC 2013, Fig. SPM.7a, SPM.8a)
(IPCC 2013, Fig. SPM.7, SPM.8)
Changes in the global water cycle in response […] will not be uniform. The contrast in precipitation between wet
and dry regions and between wet and dry seasons will
increase […].
Global mean sea level will continue to rise during the 21st century
(IPC
C 2
013,
Fig
. SP
M.9
)
Changes in Extreme Weather and Climate Events
(IPCC 2013, Table SPM.1)
AR5SREXAR4
Regional Changes: Tropical Cyclones
(IPCC 2013, Fig. 14.17)
Projections and Emissions
(IPC
C 2
013,
Fig
. TS
.4)
Limiting climate change will require substantial and sustained
reductions of greenhouse gas emissions.
(IPCC 2013, Fig. SPM.10)
CumulativeEmission
SinkSourcedtdT
dtSinkSourcedtdtdT t
t
t
t 2
1
2
1
dtSinkSourceTt
t 2
1
dtSourcet
t2
1
∆T=2ºC
Future
∆T
Present
Future
CO
2 Em
issi
on
Present
hiatus 【hɑɪéɪṭəs】隙間, 裂け目, 間隙, 活動休止(類) an interruption in the intensity or amount of something
Recent pause in global warming:the "Hiatus" problem
←Obs.2001-2010
Hiatuspatternin GCM→
Watanabe et al. (2013)MOHC (2013)
CMIP5 decadal prediction
Global mean surface temperature anomaly time seriesBars: ObservationThick line: CMIP5 initialized hindcasts. Multimodel meanDashed line: CMIP5 non-initialized hindcasts. Multimodel mean
Doblas Reyes et al. (2013)
“hiatus”
Near-TermProjection
Fig. 11.25 IPCC AR5
© Yann Arthus-Bertrand / Altitude
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