Basics of Climate Science and Key Findings of the IPCC by Youba Sokona, Vice-Chair of the IPCC, Media Workshop, 6 September 2017, Montreal, Canada

1. IPCC AR5 Synthesis Report
Media Workshop
6 September 2017
CANADA
Youba Sokona

2. Climate Change is Broad Issue
• Majority of the sciences and engineering disciplines are
involved.
• Social sciences are interested.
• Business/Industry has a stake in.
• Involves citizens, politicians, public policy experts, and
advocates.
• Every sector of the economy is affected.
• All aspects of our lives touched: environment, jobs,
health, politics, national security, arts, religion, etc.

3. What is happening in the
climate system?
What are the risks?
What can be done?

4. –18°C +15°C
Earth without air Our planet
+ 33°C
If the world had no atmosphere, it would
be very cold

5. Natural GHG effect
33 °C
Other GHG <1 °C
CO2 2 °C
H2O 31 °C
–18oC
+15oC

6. BUT THE COMPOSITION OF
AIR IS CHANGING RAPIDLY
due to human activities:
→ more GHG (CO2, CH4, NOx...)
→ more aerosol (air pollution)

7. IPCC AR5 Synthesis Report
Sources of emissions
Energy production remains the primary driver of GHG emissions
35%
24% 21% 14%
6.4%
2010 GHG emissions
Energy Sector
Agriculture,
forests and
other land uses
Industry Transport
Building
Sector
AR5 WGIII SPM

8. Enhanced GHG
effect
33 °C
+ 1 °C
Other GHG <1 °C
CO2 2 °C + 1oC
H2O 31 °C
–18oC
+16oC

10. IPCC AR5 Synthesis Report
Impacts are already underway
• Tropics to the poles
• On all continents and in the ocean
• Affecting rich and poor countries
(but the poor are more vulnerable
everywhere)
AR5 WGII SPM

11. IPCC AR5 Synthesis Report
Projected climate changes
Continued emissions of greenhouse gases will cause further
warming and changes in the climate system
Global glacier volume will
further decrease
Global mean sea level will
continue to rise during the
21st century
It is very likely that the Arctic sea
ice cover will continue to shrink
and thin as global mean surface
temperature rises
Oceans will continue to warm
during the 21st century
AR5 WGI SPM

12. +2
+4
PROBLEMATIC
• 1 - 2 billion additional people with water stress
• Impacts on cereal productivity at low latitudes
• Increased coastal flooding and storms
• Greater depth of seasonal permafrost thaw
DISASTROUS
• A 16 ºC increase in the Arctic
• 1.1 - 3.2 billion additional people with water stress
• Widespread coral mortality; risk of major
extinctions around the globe
• Substantial global impact on major crops
• Long-term prospect of sea level rise
Global temperature rise

13. IPCC AR5 Synthesis Report
Potential Impacts of Climate Change
Food and water shortages
Increased poverty
Increased displacement of
people
Coastal flooding
AR5 WGII SPM

14. Climate change: A Multiplier for Instability

15. Facing the dangers from climate change…
…there are only three options:
Mitigation, meaning measures to reduce the
pace & magnitude of the changes in global
climate being caused by human activities.
Adaptation, meaning measures to reduce the
adverse impacts on human well-being resulting
from the changes in climate that do occur.
Suffering the adverse impacts that are not
avoided by either mitigation or adaptation.

16. IPCC AR5 Synthesis Report
Mitigation Measures
More efficient use of energy
Greater use of low-carbon and no-carbon energy
• Many of these technologies exist today
Improved carbon sinks
• Reduced deforestation and improved forest management
and planting of new forests
• Bio-energy with carbon capture and storage
Lifestyle and behavioural changes
AR5 WGIII SPM

17. IPCC AR5 Synthesis Report
The window for action is rapidly closing
65% of our carbon budget compatible with a 2°C goal already used
Amount Used
1870-2011:
1900
GtCO2
Amount
Remaining:
1000
GtCO2
Total Carbon
Budget:
2900
GtCO2
AR5 WGI SPM

18. IPCC AR5 Synthesis Report
The Choices We Make Will Create Different Outcomes
With substantial
mitigation
Without
additional
mitigation
Change in average surface temperature (1986–2005 to 2081–2100)
AR5 WGI SPM

19. IPCC AR5 Synthesis Report
IPCC Fifth Assessment Report