The document summarizes key findings from the IPCC 2013/2014 report on climate change science: 1) Warming of the climate system is unequivocal and human influence is clear based on increased greenhouse gas emissions and energy stored in oceans and atmosphere. 2) If emissions continue at a high level, global temperature increases by the late 21st century will likely exceed 1.5°C compared to pre-industrial levels. 3) Limiting warming to 2°C will require substantial reductions in greenhouse emissions, as the remaining carbon budget for a 2°C target is shrinking due to ongoing emissions.

1. © Yann Arthus-Bertrand / Altitude
IPCC 2013/2014: Assessing the
Science of Climate Change
Gian-Kasper Plattner
Swiss Federal Research Institute WSL
Former Head IPCC AR5 WGI TSU
gian-kasper.plattner@wls.ch

2. 2
Observation
Understanding
Future
www.climatechange2013.org

3. Warming in 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.

4. Observation
What has changed?

5. Fig.SPM.1b
Temperature Difference 1901 to 2012 based on trend (°C)
Fig.SPM.2
Precipitation Trend (mm/yr per decade)
© IPCC 2013© IPCC 2013
Warming of the climate system
is unequivocal, […]

6. EnergyContent(1021Joule)
1980 1990 2000 2010
300
200
0
100
-100
1970
70 Mill.
TWh
Ocean warming dominates the increase
in energy stored in the climate system.
Box 3.1, Fig. 1
©IPCC2013

7. (modifiedfromGlobalCarbonProject,LeQuéréetal.2016)
2016
9.9 ± 0.5 Bill Tons C / year
Since
IPCC 1990
CO2Emissions(billtonsC/yr)
Manmade CO2 emissions are
higher than ever before.

8. Understanding
Why has it changed?

9. atmosphere, land, ocean
extreme events
water cycle
global mean sea level
Human influence on the climate
system is clear.
sea ice, glaciers, ice sheets
Cause
Worldwide Effects

10. Future
How will it change?

11. Fig. SPM.7a
Global surface temperature change for the end of
the 21st century is likely to exceed 1.5°C relative to
1850−1900 for all scenarios except RCP2.6.
Global mean surface temperature change from 1986-2005
©IPCC2013

12. Extreme Events

13. Emissions Scenarios A1B, A2:
A 1-in-20 year hottest day is likely to become a
1-in-2 year event by the end of the 21st century
in most regions
 10  more frequent
Extreme Events

14. Global mean sea level will continue to
rise over the 21st century.
Fig. SPM.9
©IPCC2013

15. Cumulative emissions of CO2 largely
determine global mean surface warming
by the late 21st century and beyond.

16. Warming of 0.8 to 2.5°C
1000 billion tons of carbon
Any climate target implies
a limited carbon budget

17. 2°C
790 bill t C
©IPCC2013
Limiting human-induced warming

18. Budget for 2°C target: 790 bill t C
CO2 emissions until 2016*: −565 bill t C
CO2 emissions in 2016 *: 9.9 bill t C
Remaining CO2 emissions: 225 bill t C
Limiting climate change will require
substantial and sustained reductions of
greenhouse gas emissions.
*updatedfromIPCC2013,WGISPM

19. Fig. SPM.8
2°C world
©IPCC2013

20. Today we have a choice.
4.5°C world2°C world
©IPCC2013
Fig. SPM.8

21. © Yann Arthus-Bertrand / Altitude
www.climatechange2013.org
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