Overview of the Fifth Assessment Report and Key Messages of the Synthesis Report
1. IPCC AR5 Synthesis Report
IPCC Fifth Assessment Report
Synthesis Report
Dr. Leo Meyer
Bogazici University, 10 September 2015
IPCC Outreach event Istanbul, Turkey
2. IPCC AR5 Synthesis Report
Key Messages
➜ Human influence on the climate system is
clear; impacts are already there
➜ The more we disrupt our climate, the more we
risk severe, pervasive and irreversible impacts
➜ We have the means to limit climate change and
build a more prosperous, sustainable future
AR5 WGI SPM, AR5 WGII SPM, AR5 WGIII SPM
3. IPCC AR5 Synthesis Report
Humans are changing the climate
Year
Globally averaged combined land and ocean surface
temperatures
It is extremely likely that we are the dominant cause of warming
since the mid-20th century
AR5 WGI SPM
4. IPCC AR5 Synthesis Report
AR5 SYR SPM
CO2 is the main driver of global warming
5. IPCC AR5 Synthesis Report
GHG emissions growth between 2000 and 2010 has been
larger than in the previous three decades
AR5 WGIII SPM
6. IPCC AR5 Synthesis Report
Impacts are already underway
• Tropics to the poles
• On all continents and in the ocean
• Affecting rich and poor countries
AR5 WGII SPM
7. IPCC AR5 Synthesis Report
Observations of climate change in Mediterranean
Basin
• Wildfires significantly
increased after the 1970s
• Including in France, Greece,
Italy, Portugal, Spain, and
Turkey
AR5 WGII ch.23
8. “There is evidence that human influences on
the climate system are implicated in the
current Syrian conflict “ (PNAS March 2015)
“Fertile
Crescent”
9. IPCC AR5 Synthesis Report
Projections
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
10. IPCC AR5 Synthesis Report
Sea level rise
A 1 m sea level rise in
Turkey could affect 3
million additional
people and put US$12
billion capital value at
risk, with around US$20
billion adaptation costs
AR5 WGII ch.23
Ortakoy mosque, Istanbul
11. IPCC AR5 Synthesis Report
Projected Impacts of Climate Change
Food and water shortages
Increased poverty
Increased displacement of
people
Coastal flooding
AR5 WGII SPM
12. IPCC AR5 Synthesis Report
Water shortages
The Mediterranean region will
suffer agricultural and forests
production losses due to
increasing heat waves and
droughts exacerbated also by
the competition for water
Turkey plans to more than
double water abstraction by
2023
AR5 WGII ch.23
13. IPCC AR5 Synthesis Report
Climate Change Poses Risk for Food Production
AR5 SYR SPM
14. Without additional mitigation, global mean surface temperature
is projected to increase by 3.7 to 4.8 0C over the 21st century…
14
Based on WGII AR5 Figure 19.4
16. IPCC AR5 Synthesis Report
Limiting Temperature Increase to 2˚C
Global GHG emissions reduction of 40-70 % in
2050 compared to 2010
Net zero or negative GHG emissions in 2100
Global emissions to curb within next 5-15 years
AR5 WGIII SPM
Ambitious mitigation is affordable
20. 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
21. 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
Without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist driven by growth in global population and economic activities. Baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 to 4.8°C compared to pre-industrial levels.
For such large magnitudes of warming, the Working Group II contribution to AR5 highlights the increase in the likelihood of severe, pervasive, and challenging impacts. Risks include potential adverse impacts on agricultural production worldwide, potentially extensive ecosystem impacts, and increasing species extinction risk (high confidence), as well as possible crossing of thresholds that lead to disproportionately large earth system responses (low confidence). The precise levels of climate change sufficient to trigger tipping points (critical thresholds) remain uncertain, but the likelihood of crossing tipping points in the earth system or interlinked human and natural systems decreases with reduced greenhouse gas emissions.
The overall risks of climate change impacts can be reduced by limiting the rate and magnitude of climate change. Risks are reduced substantially under the assessed scenario in ambitious mitigation scenarios compared to business as usual projections.
