1. Key Findings of the IPCC Fourth Assessment Report
WMO
UNEP
R. K. Pachauri
Chairman, IPCC
Director-General, TERI
Brussels
31st March 2009

2. The Intergovernmental Panel on Climate Change (IPCC)

3. The IPCC
“The General Assembly […] endorses action of the World Meteorological Organization and the United Nations Environment Programme in jointly establishing an Intergovernmental Panel on Climate Change to provide international coordinated scientific assessments of the magnitude, timing and potential environmental and socio-economic impact of climate change and realistic response strategies […].”
United Nations General Assembly
43rd session resolution, 6th December 1988
(UN GA 43rd session, 70th Plenary meeting, 6 December 1988)
The work of the IPCC is guided by the mandate given to it by its parent organisations the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP). At its 14th Session the Panel approved principles governing its work. Source:
The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the
scientific, technical and socio-economic information relevant to understanding the scientific basis of
risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.
IPCC reports should be neutral with respect to policy, although they may need to deal objectively with
scientific, technical and socio-economic factors relevant to the application of particular policies.
Source: Principles governing IPCC work p.1 3

4. Writing and review process of the IPCC assessment reports
Experts review the first draft of the report
Governments and experts review the second draft of the report and the draft Summary for Policymakers
Governments review word-by-word the revised draft Summary for Policymakers

5. The IPCC Fourth Assessment Report (2007)
+2500 scientific expert reviewers
800 contributing authors
450 lead authors
+130 countries

6. I. Observed changes in climate
Warming of the climate system is unequivocal, as is now evident from observations of increases in average air and ocean temperatures, widespread melting of snow and ice, and rising average sea level
Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level (Figure SPM.1). {1.1}

7. I. Observed changes in climate
Global average
sea level
Northern
hemisphere
snow cover
Global average temperature

8. I. Observed changes in climate
From 1900 to 2005, precipitation increased significantly in eastern parts of North and South America, northern
Europe and northern and central Asia but declined in the Sahel, the Mediterranean, southern Africa and parts of
southern Asia. Globally, the area affected by drought has likely increased since the 1970s. {1.1}
It is very likely that over the past 50 years: cold days, cold nights and frosts have become less frequent over most
land areas, and hot days and hot nights have become more frequent. It is likely that: heat waves have become more frequent over most land areas, the frequency of heavy precipitation events has increased over most areas, and since1975 the incidence of extreme high sea level has increased worldwide. {1.1}
Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1300 years. {1.1}
SYR SPM p.1

9. to the increase in anthropogenic
II. Causes of change
Global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 2004
CO2 annual emissions grew by about 80% between 1970 and 2004
Most of the observed increase in temperatures since the mid-20th century is very likely due
to the increase in anthropogenic
GHG concentrations
Global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 2004 (Figure SPM.3).5 {2.1}
Carbon dioxide (CO2) is the most important anthropogenic GHG. Its annual emissions grew by about 80% between 1970 and The long-term trend of declining CO2 emissions per unit of energy supplied reversed after {2.1}
Atmospheric concentrations of CO2 (379ppm) and CH4 (1774 ppb) in 2005 exceed by far the natural range over
the last 650,000 years.
Most of the observed increase in globally-averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.
SYR SPM p.4

10. Global temperature change
II. Causes of change
Global temperature change
Observations 1
0.5
Models using only
natural forcing
Temperature anomaly
Models using both
natural and
anthropogenic forcing
Figure SPM.4. Comparison of observed continental- and global-scale changes in surface temperature with results simulated by climate models using either natural or both natural and anthropogenic forcings. Decadal averages of observations are shown for the period (black line) plotted against the centre of the decade and relative to the corresponding average for the period Lines are dashed where spatial coverage is less than 50%. Blue shaded bands show the 5-95% range for 19 simulations from 5 climate models using only the natural forcings due to solar activity and volcanoes. Red shaded bands show the 5-95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings. {Figure 2.5}
SYR SPM p.5
During the past 50 years, the sum of solar and volcanic forcings would likely have produced cooling. Observed
patterns of warming and their changes are simulated only by models that include anthropogenic forcings.
Difficulties remain in simulating and attributing observed temperature changes at smaller than continental scales.
Year
Observed patterns of warming are simulated only by models that include anthropogenic forcings

11. III. Projected climate change and impacts
Projected surface temperature changes
( relative to )
Figure SPM. 6. Projected surface temperature changes for the late 21st century ( ). The map shows the multi-AOGCM average projection for the A1B SRES scenario. All temperatures are relative to the period {Figure 3.2}
For the next two decades a warming of about 0.2°C per decade is projected for a range of SRES emission
scenarios. Even if the concentrations of all GHGs and aerosols had been kept constant at year 2000 levels, a
further warming of about 0.1°C per decade would be expected. Afterwards, temperature projections increasingly
depend on specific emission scenarios. {3.2}
SYR SPM p.6
(oC)
Continued emissions would lead to further warming of 1.8ºC to 4ºC over the 21st century

12. III. Projected climate change and impacts
Climate change could lead to some abrupt or irreversible impacts
Partial loss of ice sheets on polar land could imply metres of sea level rise, major changes in coastlines and inundation of low-lying areas
20-30% of species are likely to be at risk of extinction if increases in warming exceed °C
Anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the climate change. {3.4}
Partial loss of ice sheets on polar land could imply metres of sea level rise, major changes in coastlines and inundation of low-lying areas, with greatest effects in river deltas and low-lying islands. Such changes are
projected to occur over millennial time scales, but more rapid sea level rise on century time scales cannot be excluded. {3.4}
Climate change is likely to lead to some irreversible impacts. There is medium confidence that approximately % of species assessed so far are likely to be at increased risk of extinction if increases in global average warming exceed oC (relative to ). As global average temperature increase exceeds about 3.5oC, model projections suggest significant extinctions (40-70% of species assessed) around the globe. {3.4}
SYR SPM p.13
Large scale and persistent changes in Meridional Overturning Circulation would have impacts on marine ecosystem productivity, fisheries, ocean CO2 uptake and terrestrial vegetation 12

13. III. Projected climate change and impacts Systems and sectors likely to be especially affected
Particular ecosystems: tundra, boreal forest, mountain regions, mediterranean-type ecosystems, tropical rainforests; mangroves and salt marshes; coral reefs; the sea ice biome
Water resources in some dry regions at mid-latitudes and in the dry tropics, due to changes in rainfall and evapo-transpiration, and in areas dependent on snow and ice melt
Agriculture in low-latitudes, due to reduced water availability
Some systems, sectors and regions are likely to be especially affected by climate change.12 {3.3.3}
Systems and sectors: {3.3.3}
• particular ecosystems:
• terrestrial: tundra, boreal forest and mountain regions because of sensitivity to warming;
mediterranean-type ecosystems because of reduction in rainfall; and tropical rainforests where
precipitation declines
• coastal: mangroves and salt marshes, due to multiple stresses
• marine: coral reefs due to multiple stresses; the sea ice biome because of sensitivity to warming
• water resources in some dry regions at mid-latitudes and in the dry tropics, due to changes in rainfall and evapotranspiration, and in areas dependent on snow and ice melt
• agriculture in low-latitudes, due to reduced water availability
• low-lying coastal systems, due to threat of sea level rise and increased risk from extreme weather events
• human health in populations with low adaptive capacity.
SYR SPM p.11
Low-lying coastal systems, due to threat of sea level rise and increased risk from extreme weather events
Human health in populations with low adaptive capacity 13

14. III. Projected climate change and impacts Regions likely to be especially affected
The Arctic, because of the impacts of high rates of warming on natural systems and human communities
Africa, because of low adaptive capacity and projected climate change impacts
Small islands, which are highly vulnerable to projected sea level rise
Some systems, sectors and regions are likely to be especially affected by climate change.
Regions: {3.3.3}
• the Arctic, because of the impacts of high rates of projected warming on natural systems and human communities
• Africa, because of low adaptive capacity and projected climate change impacts
• Small islands, where there is high exposure of population and infrastructure to projected climate change impacts
• Asian and African megadeltas, due to large populations and high exposure to sea level rise, storm surges
and river flooding.
Within other areas, even those with high incomes, some people (such as the poor, young children, and the elderly)
can be particularly at risk, and also some areas and some activities. {3.3.3}SYR SPM p.11
Asian and African megadeltas, due to large populations and high exposure to sea level rise, storm surges and river flooding 14

15. III. Projected climate change and impacts
Negative impacts in Europe
Inland and coastal flooding
Health risks due to heat-waves
Reduction of water availability and crop productivity in South Europe
Species losses and reduced snow cover in mountains
Europe
• Climate change is expected to magnify regional differences in Europe’s natural resources and assets. Negative
impacts will include increased risk of inland flash floods, and more frequent coastal flooding and increased erosion (due to storminess and sea-level rise)
• Mountainous areas will face glacier retreat, reduced snow cover and winter tourism, and extensive species losses (in some areas up to 60% under high emissions scenarios by 2080)
• In Southern Europe, climate change is projected to worsen conditions (high temperatures and drought) in a regionalready vulnerable to climate variability, and to reduce water availability, hydropower potential, summer tourism and, in general, crop productivity
• Climate change is also projected to increase the health risks due to heat-waves, and the frequency of wildfires

16. IV. Adaptation and mitigation options
Adaptive capacity is intimately connected to social and economic development
Even societies with high adaptive capacity remain vulnerable to climate change
Adaptation can reduce vulnerability especially when it is embedded within broader sectoral initiatives
Some planned adaptation to climate change is already occurring on a limited basis. Adaptation can reduce vulnerability especially when it is embedded within broader sectoral initiatives (Table SPM.4).
SYR SPM p.14
Adaptive capacity is intimately connected to social and economic development, but it is not evenly distributed across and within societies. Even societies with high adaptive capacity remain vulnerable to climate change, variability and extremes. For example, a heat wave in 2003 caused high levels of mortality in European cities (especially among the elderly), and in 2005 Hurricane Katrina caused large human and financial costs in the United States.
SYR Topic 4 p.2
Societies across the world have a long record of adapting and reducing their vulnerability to the impacts of weather- and climate-related events such as floods, droughts and storms. Nevertheless, additional adaptation measures will be required at regional and local levels to reduce the adverse impacts of projected climate change and variability, regardless of the scale of mitigation undertaken over the next two to three decades.
However, adaptation alone is not expected to cope with all the projected effects of climate change, especially over the long term as most impacts increase in magnitude.
SYR Topic 4 p.1
But adaptation alone is not expected to cope with all the projected effects of climate change

17. IV. Adaptation and mitigation options
All stabilisation levels assessed can be achieved by deployment of a portfolio of technologies that are currently available or expected to be commercialised in coming decades
This assumes that investment flows, technology transfer and incentives are in place for technology development
There is high agreement and much evidence that all stabilisation levels assessed can be achieved by
deployment of a portfolio of technologies that are either currently available or expected to be
commercialised in coming decades, assuming appropriate and effective incentives are in place for their development, acquisition, deployment and diffusion and addressing related barriers.
Without substantial investment flows and effective technology transfer, it may be difficult to achieve emission
reduction at a significant scale. Mobilizing financing of incremental costs of low-carbon technologies is important.
{5.5}

18. Key mitigation technologies
IV. Adaptation and mitigation options
Key mitigation technologies
Efficient lighting; efficient appliances; improved insulation; solar heating and cooling;
alternatives for fluorinated gases in insulation and appliances
Efficiency; fuel switching; renewables; combined heat and power; nuclear power; early applications of CO2 capture & storage
Energy
Supply
Transport
More fuel efficient vehicles; hybrid vehicles; biofuels; modal shifts from road transport to rail and public transport systems
Buildings
SYR SPM 18

19. IV. Adaptation and mitigation options
Key mitigation instruments, policies and practices:
Regulations and standards
Taxes and charges
Effective carbon-price signal
Appropriate energy infrastructure investments
Research, development and demonstration
A wide variety of policies and instruments are available to governments to create the incentives for mitigation action. Their applicability depends on national circumstances and sectoral context (Table SPM.5). {4.3}
They include integrating climate policies in wider development policies, regulations and standards, taxes and
charges, tradable permits, financial incentives, voluntary agreements, information instruments, and research,
development and demonstration (RD&D). {4.3}
An effective carbon-price signal could realise significant mitigation potential in all sectors. Modelling studies
show global carbon prices rising to US$/tCO2-eq by 2030 are consistent with stabilisation at around 550
ppm CO2-eq by For the same stabilisation level, induced technological change may lower these price ranges to 5-65 US$/tCO2-eq in {4.3}
There is also high agreement and medium evidence that changes in lifestyle, behaviour patterns and management practices can contribute to climate change mitigation across all sectors. {4.3}
Greater cooperative efforts and expansion of market mechanisms will help to reduce global costs for achieving a
given level of mitigation, or will improve environmental effectiveness. Efforts can include diverse elements such
as emissions targets; sectoral, local, sub-national and regional actions; RD&D programmes; adopting common
policies; implementing development oriented actions; or expanding financing instruments. {4.5} SYR SPM p.19
Future energy infrastructure investment decisions, expected to exceed 20 trillion US$16 between 2005 and 2030,
will have long-term impacts on GHG emissions, because of the long life-times of energy plants and other infrastructure capital stock. The widespread diffusion of low-carbon technologies may take many decades, even if
early investments in these technologies are made attractive. Initial estimates show that returning global energyrelated CO2 emissions to 2005 levels by 2030 would require a large shift in investment patterns, although the net additional investment required ranges from negligible to 5-10%. {4.3} SYR SPM p.18
International and regional cooperation
Changes in lifestyle & management practices

20. V. Mitigation targets Characteristics of stabilisation scenarios
Stabilization
level
(ppm CO2-eq)
Global mean temp. increase
(ºC)
Year CO2 needs to peak
Global sea level rise above pre- industrial from thermal expansion
(m)
445 – 490
2.0 – 2.4
2000 – 2015
0.4 – 1.4
490 – 535
2.4 – 2.8
2000 – 2020
0.5 – 1.7
535 – 590
2.8 – 3.2
2010 – 2030
0.6 – 1.9
590 – 710
3.2 – 4.0
2020 – 2060
0.6 – 2.4
Table SPM.6. Characteristics of post-TAR stabilisation scenarios and resulting long-term equilibrium global average temperature and the sea level rise component from thermal expansion only. {Table 5.1}a
Mitigation efforts and investments over the next two to three decades will have a large impact on opportunities to achieve lower stabilisation levels. Delayed emission reductions significantly constrain the opportunities to achieve lower stabilisation levels and increase the risk of more severe climate change impacts.
Sea level rise under warming is inevitable. Thermal expansion would continue for many centuries after GHG
concentrations have stabilised, for any of the stabilisation levels assessed, causing an eventual sea level rise much larger than projected for the 21st century. The eventual contributions from Greenland ice sheet loss could be several metres, and larger than from thermal expansion, should warming in excess of °C above preindustrial be sustained over many centuries. The long time scales of thermal expansion and ice sheet response to warming imply that stabilisation of GHG concentrations at or above present levels would not stabilise sea level for many centuries. {5.3, 5.4}
SYR SPM p.21
Mitigation efforts over the next two to three decades will have a large impact on opportunities to achieve lower stabilisation levels

21. V. Mitigation targets Impacts of mitigation on GDP growth
(for stabilisation scenario of ppm CO2-eq)
GDP
Cost of mitigation in 2030: max 3% of global GDP
Mitigation would postpone GDP growth by one year at most over the medium term
GDP without mitigation
GDP with stringent mitigation
Current
Time
2030
Schematic graph

22. - less than 0.12 percentage points in annual GDP
V. Mitigation targets
In 2050, global average costs for mitigation are between a 1% gain and 5.5% decrease of global GDP
- less than 0.12 percentage points in annual GDP
Mitigation actions can result co-benefits that may offset a substantial fraction of mitigation costs
Costs of impacts of climate change will increase as temperatures increase
Impacts of climate change are very likely to impose net annual costs which will increase over time as global
temperatures increase. Aggregate estimates of costs mask significant differences in impacts across sectors, regions and populations and very likely underestimate damage costs because they cannot include many non-quantifiable impacts. {5.7}
SYR SPM p.23
In 2050, global average macro-economic costs for mitigation towards stabilisation between 710 and 445ppm CO2-eq are between a 1% gain and 5.5% decrease of global GDP (Table SPM.7). This corresponds to slowing average annual global GDP growth by less than 0.12 percentage points. {5.6}
SYR SPM p.22
There is high agreement and much evidence that mitigation actions can result in near-term co-benefits (e.g.
improved health due to reduced air pollution) that may offset a substantial fraction of mitigation costs. {4.3}
Early mitigation actions would avoid further locking in carbon intensive infrastructure and reduce climate change and associated adaptation needs.
Choices about the scale and timing of GHG mitigation involve balancing the economic costs of more rapid
emission reductions now against the corresponding medium-term and long-term climate risks of delay. {5.7}
Choices about the scale and timing of mitigation involve balancing the economic costs of more rapid emission reductions against the medium and long term risks of delay

23. Beyond the Kyoto Protocol
V. Mitigation targets
Beyond the Kyoto Protocol
Developed countries need to significantly reduce their emissions below 1990 levels:
10-40% by 2020
40-95% by 2050
The Kyoto Protocol is currently constrained by the modest emission limits. It would be more effective if the first commitment period is followed-up by measures to achieve deeper reductions and the implementation of policy instruments covering a higher share of global emissions.
Under most equity interpretations, developed countries as a group would need to reduce their emissions significantly by 2020 (10–40% below 1990 levels) and to still lower levels by 2050 (40–95% below 1990 levels) for low to medium stabilization levels (450–550ppm CO2-eq). Under most of the regime designs considered for such stabilization levels,
developing-country emissions need to deviate below their projected baseline emissions within the next few decades.
WG3 TS p.89
Coordinated policies and measures could be an alternative to or complement internationally agreed targets for emission reductions. A number of policies have been discussed in the literature that would achieve this goal, including taxes (such as carbon or energy taxes); trade coordination/liberalization; R&D; sectoral policies and policies that modify foreign direct
investment. Under one proposal, all participating nations – industrialized and developing alike – would tax their domestic carbon usage at a common rate, thereby achieving cost-effectiveness.
WG3 TS p.91
Developing country emissions need to deviate below their projected baseline within the next few decades

24. VI. Towards a new development path
Our settlements and communities presently lack the resilience to enable them to weather future energy and environmental shocks
The only way forward is creating a sober society, where resources are more valorised and consumption is reduced
Atmosphere, land, water, biodiversity and human society are linked in a complex web of interactions and feedbacks
By unleashing our individual & collective genius, we can build ways of living that are more connected, more enriching and that recognise the biological limits of our planet
Transition Initiatives are based on four key assumptions:
1) That life with dramatically lower energy consumption is inevitable, and that it‟s better to plan for it than to be taken by surprise
2) That our settlements and communities presently lack the resilience to enable them to weather the severe energy shocks that will accompany „Peak Oil‟.
3) That we have to act collectively, and we have to act now.
4) That by unleashing the collective genius of those around us to creatively and proactively design our energy descent, we can build ways of living that are more connected, more enriching and that recognise the biological limits of our planet.
WWF UK published earlier this year a report entitled Weathercocks and Signposts: The environment movement at a crossroads (WWF UK, 2008). recognises „that environmental challenges will not be met while maintaining a narrow focus on the happy coincidence of economic self-interest and environmental prudence‟.
The Earth functions as a system: atmosphere,
land, water, biodiversity and human
society are all linked in a complex web of
interactions and feedbacks.
The interconnections of global problems call for the search of global, comprehensive solutions by opposition to sectoral approaches. Hence the need for inter-disciplinary cooperation allowing a comprehensive understanding of the implications of each individual and collective choice. The pleasure to be part of a collective effort, driven by cooperation, must replace the fight for individual profit, driven by competition, which has become a basis of our living together.
The only way forward is creating a sober society, where resources become more valorized and consumption is reduced.
Each human being possesses under-exploited resources of wisdom and creativity to understand the depth of the changes needed and find one’s own solutions to resolve the crisis. 24

25. VI. Towards a new development path
The dominant path to industrialization has been characterized by high concurrent GHG emissions
Committing to alternative development paths would require major changes in areas other than climate change:
Economic structure
Technology
Geographical distribution of activities
Consumption patterns
Urban design and transport infrastructure
Demography
Institutional arrangements and trade patterns
For much of the last century, the dominant path to industrialization was characterized by high concurrent GHG emissions.
The IPCC Third Assessment Report concluded that committing to alternative development paths can result in very different future GHG emissions. Development paths leading to lower emissions will require major policy changes in areas other than climate change.
GHG emissions are subject to human intervention. Such factors include economic structure, technology, geographical distribution of activities, consumption patterns, urban design and transport infrastructure, demography, institutional arrangements and trade patterns.
WG3 Chapter 12 p.11

26. Key policies Improving scientific understanding of the issues at stake
Promoting research & development and technology transfer
Informing and educating
Mainstreaming environmental policies in decision making
Internalising the environmental costs of economic activity
E.g. effective carbon-price signal
Effective policies are those that provide long-term signals and incentives on a predictable basis
A wide variety of policies and instruments are available to governments to create the incentives for mitigation action. Their applicability depends on national circumstances and sectoral context (Table SPM.5). {4.3}
They include integrating climate policies in wider development policies, regulations and standards, taxes and charges, tradable permits, financial incentives, voluntary agreements, information instruments, and research, development and demonstration (RD&D). {4.3}
There is also high agreement and medium evidence that changes in lifestyle, behaviour patterns and management practices can contribute to climate change mitigation across all sectors. {4.3}
Greater cooperative efforts and expansion of market mechanisms will help to reduce global costs for achieving a given level of mitigation, or will improve environmental effectiveness. Efforts can include diverse elements such as emissions targets; sectoral, local, sub-national and regional actions; RD&D programmes; adopting common policies; implementing development oriented actions; or expanding financing instruments. {4.5} SYR SPM p.19
Future energy infrastructure investment decisions, expected to exceed 20 trillion US$16 between 2005 and 2030, will have long-term impacts on GHG emissions, because of the long life-times of energy plants and other infrastructure capital stock. The widespread diffusion of low-carbon technologies may take many decades, even if early investments in these technologies are made attractive. Initial estimates show that returning global energyrelated CO2 emissions to 2005 levels by 2030 would require a large shift in investment patterns, although the net additional investment required ranges from negligible to 5-10%. {4.3} SYR SPM p.18
An effective carbon-price signal could realise significant mitigation potential in all sectors. Modelling studies show global carbon prices rising to US$/tCO2-eq by 2030 are consistent with stabilisation at around 550ppm CO2-eq by For the same stabilisation level, induced technological change may lower these price ranges to 5-65 US$/tCO2-eq in {4.3} 26

27. Gandhi was once asked if he expected India to attain the same standard
of living as Britain. He replied:
It took Britain half the resources of the planet to achieve this prosperity.
How many planets will a country like India require!