Post on 23-Jan-2021
Anthropocene: The closing door of climate targets Thomas Stocker Climate and Environmental Phyics, University of Bern
Grantham Lecture 2013
1. The Anthropocene: A new Epoch
2. Climate Change: The IPCC AR5
3. Climate Targets: What can we achieve?
Anthropocene: The closing door of climate targets Thomas Stocker Climate and Environmental Phyics, University of Bern
Grantham Lecture 2013
Anthropocene: Crutzen and Stoermer (2000)
(Lüthi et al.,2008, NOAA)
+30% 2013
Unprecedented: CO2 of the past 800,000 years
( mod
ified
from
Pet
ers
et a
l., 2
013)
2012
Unprecedented: CO2 Emissions by human activity
9.7±0.5 GtC/yr
+57% since Rio '92
1. The Anthropocene: A new Epoch
2. Climate Change: The IPCC AR5
3. Climate Targets: What can we achieve?
Anthropocene: The closing door of climate targets
Grantham Lecture 2013
to assess on a comprehensive, objective, open and transparent basis the scientific, [...] information
relevant to understanding the scientific basis of risk of human-induced climate change,
...
Charge of the Intergovernmental Panel on Climate Change (IPCC):
www.climatechange2013.org
Key SPM Messages
19 Headlines on less than 2 Pages
8
2009: WGI Outline Approved
14 Chapters, >106 Words Atlas of Regional Projections
54,677 Review Comments by 1089 Experts
2010: 259 Authors Selected
Summary for Policymakers ca. 14,000 Words
9
Observation
Understanding
Future
Warming of the climate system is unequivocal, [...]
Human influence on the climate system is clear.
Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.
Anthropocene: A key component in the Earth system
(Sto
cker
, 201
3)
Global Mean Temperature Change
Anthropogenic CO2 Emissions
Cumulative Emissions from 1870 to 2011: 515 GtC
Warming since 1880: 0.85 °C
Transient Climate Response to
Cumulative Carbon Emissions (TCRE)
Cumulative emissions of CO2 and global mean surface temperature response are approximately linearly related.
IPC
C 2
013,
Fig
. 12.
43
Glo
bal m
ean
war
min
g (°
C)
Cumulative CO2 Emissions (GtC) Cumulative CO2 Emissions (GtC)
Transient Climate Response to Cumulative Carbon Emissions
TRCE = 0.8 to 2.5°C per 1000 GtC
CO2-induced warming < 2°C implies less than 1000 GtC
IPC
C 2
013,
Fig
. SPM
.10
Anthropogenic warming < 2°C implies less than 800 GtC
IPC
C 2
013,
Fig
. SPM
.10
Limiting climate change will require substantial and sustained reductions of
greenhouse gas emissions.
Cumulative CO2 emissions to date: about 515 GtC
IPC
C 2
013,
Fig
. SPM
.10
Limiting climate change will require substantial and sustained reductions of
greenhouse gas emissions.
∆T(1850-1900 to 2100) Likelihood Scenarios
> 1.5°C likely RCP4.5, RCP6.0, RCP8.5
> 2°C likely RCP6.0, RCP8.5
> 2°C more likely than not RCP4.5
1. The Anthropocene: A new Epoch
2. Climate Change: The IPCC AR5
3. Climate Targets: What can we achieve?
Anthropocene: The closing door of climate targets
Grantham Lecture 2013
( mod
ified
from
Pet
ers
et a
l., 2
013)
CO2 Emissions: Nearly exponential increase
~ e+1.8 %/yr ∙ t
2020
Academic scenarios to reach the climate target 2°C
2020
2030
Academic scenarios to reach the climate target 2°C
2040
2020
2030
Academic scenarios to reach the climate target 2°C
)s,t(TCRET 1f⋅=∆
∫=∞ dt)t(EC
∞⋅=∆ CTCRET
Cumulative CO2 Emissions:
Peak Warming:
Determinants of Peak Warming
Start Time of CO2 Emission Reduction
Rate of CO2 Emission Reduction
Clim
ate
Targ
et (°
C)
Starting Year of Emissions Reduction
The closing door of climate targets
(Sto
cker
, 201
3)
Rate of CO2 Emission Reduction
Clim
ate
Targ
et (°
C)
Starting Year of Emissions Reduction
The closing door of climate targets
(Sto
cker
, 201
3)
InstantaneousEmission Stop
Clim
ate
Targ
et (°
C)
Starting Year of Emissions Reduction
The closing door of climate targets
(Sto
cker
, 201
3)
Clim
ate
Targ
et (°
C)
The closing door of climate targets
(Sto
cker
, 201
3)
Clim
ate
Targ
et (°
C)
The closing door of climate targets
(Sto
cker
, 201
3)
)s,t(dtdTCRE
dtTd
111
f⋅=∆
∞⋅=∆ CTCRETPeak Warming:
Mitigation Delay Sensitivity:
Trdt
Td
1
∆⋅≈∆
Rate of CO2 Emission Increase
Mitigation delay: Peak temperature rises fast
Peak warming rises at the rate of emissions
(Alle
n an
d St
ocke
r, 20
13)
Mitigation delay: Peak temperature rises fast
Mitigation delay: Peak temperature rises fast
20th century warming: ≈ 0.08 °C per decade
1998 to 2012 warming: ≈ 0.05 °C per decade
increasing of peak warming under continued emissions:
≈ 0.4 °C per decade
Committed peak warming rises 3 to 8 times faster than observed warming
1951 to 2012 warming: ≈ 0.12 °C per decade
RCP8.5 CO2eq = 1313 ppm
IPC
C 2
013,
Fig
. SPM
.8
RCP2.6 CO2eq = 475 ppm
Warming of the climate system is unequivocal.
Human influence on the climate system is clear.
Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.
Climate targets disappear rapidly as CO2 emissions continue
Committed peak warming increases at rates similar to those of the emission increase, i.e. 3 to 8 times faster than the observed warming
less-than-2°C world ─ more-than- 4°C world:
Today, we have a choice.