Download SB 14-66 Climate Change: The Latest United

The Sc ottish Parliament and Scottis h Parliament Infor mation C entre l ogos .
SPICe Briefing
Climate Change: The Latest United
Nations Science
30 September 2014
14/66
Dan Barlow
Under the auspices of the United Nations, the Intergovernmental Panel on Climate Change
(IPCC) provides a regular assessment of the science of climate change. This briefing
summarises the findings of three IPCC reports published in 2013 and 2014 that together
comprise the Fifth Assessment Report:



The Physical Science Basis.
Impacts, Adaptation and Vulnerability.
Mitigation of Climate Change.
The briefing also describes a range of reactions to the publication of these reports.
Observed change in average surface temperature 1901-2012
Source: IPCC 2013a, Figure SPM 1b
CONTENTS
EXECUTIVE SUMMARY .............................................................................................................................................. 3
TERMINOLOGY ........................................................................................................................................................... 4
BACKGROUND............................................................................................................................................................ 5
IPCC ............................................................................................................................................................................. 5
ASSESSMENT REPORTS ...................................................................................................................................... 5
CLIMATE CHANGE 2013: THE PHYSICAL SCIENCE BASIS (WORKING GROUP I)............................................. 7
CHANGES IN THE CLIMATE SYSTEM - OBSERVATIONS................................................................................... 7
UNDERSTANDING THE CLIMATE SYSTEM ......................................................................................................... 9
CUASES OF CLIMATE CHANGE ............................................................................................................................ 9
FUTURE GLOBAL AND REGIONAL CLIMATE CHANGE ...................................................................................... 9
LIMITING GLOBAL TEMPERATURE RISE ........................................................................................................... 13
CLIMATE CHANGE 2014: IMPACTS, ADAPTATION AND VULNERABILITY (WORKING GROUP II) ................ 15
IMPACTS ................................................................................................................................................................ 15
ADAPTATION APPROACHES .............................................................................................................................. 16
RISKS, OPPORTUNITIES AND ADAPTATION POTENTIAL ............................................................................... 18
ADAPTATION PRINCIPLES AND PATHWAYS .................................................................................................... 18
CLIMATE CHANGE 2014: MITIGATION OF CLIMATE CHANGE (WORKING GROUP III) ................................... 21
EMISSIONS TRENDS ............................................................................................................................................ 21
EMISSION REDUCTION PATHWAYS .................................................................................................................. 22
MITIGATION COSTS ............................................................................................................................................. 23
SECTORS .............................................................................................................................................................. 24
NATIONAL MITIGATION STRATEGIES AND POLICIES ..................................................................................... 26
RESPONSES TO THE PUBLICATION OF AR5 .................................................................................................... 26
UNFCCC PROCESS – NEXT STEPS ....................................................................................................................... 28
SOURCES .................................................................................................................................................................. 29
RELATED BRIEFINGS .............................................................................................................................................. 30
2
EXECUTIVE SUMMARY
Under the auspices of the United Nations, the Intergovernmental Panel on Climate Change
(IPCC) prepare comprehensive reports about climate change at regular intervals based on the
most recent scientific, technical and socio-economic information. The Fifth Assessment Report
(AR5) sets out the current state of scientific knowledge and comprises three Working Group
reports that cover: the science of climate change; impacts, adaptation and vulnerability to
climate change; and the mitigation of climate change.
Working Group I (WG1) (on the science) reports that observations of climate change include an
average increase in land and ocean temperature of 0.85oC between 1880 and 2012, reductions
in annual mean Arctic sea ice equivalent to 3.5 - 4.1% per decade between 1979 and 2012 and
a rise in global mean sea level of 0.19m between 1901 and 2010.
The report also states that “It is extremely likely that human influence has been the dominant
cause of the observed warming since the mid-20th century” and that “substantial and sustained”
cuts in greenhouse gas emissions would be required to curb climate change. The report sets
out four emission scenarios. In three of these temperatures are likely to exceed 1.5oC by 2100
(compared to 1850-1900), and in two scenarios they are likely to exceed 2oC.
The report of Working Group II (WGII) (on impacts and adaptation) highlights impacts that
include changes in the quantity and quality of water resources, changes in the geographic range
and abundance of many species, and an overall reduction in crop yields. It also notes that
marginalised people are particularly vulnerable to the impacts of climate change. The report
finds that experience is growing in the public and private sector and within communities, and
governments are beginning to prepare adaptation plans and policies. The report notes that
greater warming will increase the likelihood of “severe, pervasive, and irreversible impacts”.
Working Group III (WGIII) considers the mitigation of climate change. The report identifies the
four largest sources of emissions in 2010 as i) electricity and heat production, ii) agriculture,
forestry and land use, iii) industry and iv) transport. Between 2000 and 2010 emissions of
greenhouse gas emissions have increased by an average of 2.2% per year. The report cites
economic growth and population growth as the two most significant drivers of increasing CO2
emissions from fossil fuel combustion. According to the WGIII report scenarios consistent with
achieving carbon dioxide concentrations in the atmosphere that are “likely”’ to limit warming to
less than 2o degrees above pre-industrial levels are characterised by reductions in global GHG
emissions of 40 to 70% in 2050 compared to 2010, rapid increases in energy efficiency and
more than tripling the share of zero- and low- carbon energy supply by 2050.
The WGIII report highlights that despite a significant increase in plans and strategies aimed at
curbing climate emissions there has “not yet been a substantial deviation in global emissions
from the past trend.” The authors also suggest that delays to mitigation efforts will make the
transition to low emission levels over the longer-term more challenging and constrain the
options available to ensure that temperature rise is limited to below 2 oC.
3
TERMINOLOGY
AR4: The Fourth Annual Report of the IPCC published in 2007.
AR5: The Fifth Annual Report of the IPCC. Working Group Reports on The Physical Science
Basis (Working Group I), Impacts, Adaptation and Vulnerability (Working Group II) and
Mitigation of Climate Change (Working Group III) have been published in September 2013,
March 2014 and April 2014 respectively. A synthesis report is due to be published in November
2014.
Atlantic Meridional Overturning Circulation: A significant current in the Atlantic Ocean that
brings warm, salty water northwards in the upper layers of the ocean and takes colder water
southwards in the lower levels. This system circulates heat from the Tropics and Southern
Hemisphere towards the North Atlantic where it is transferred to the atmosphere.
Cancún pledges: At the December 2010 United Nations (UN) Climate Conference in Cancún,
Mexico, developed and developing countries put forward pledges to reduce national emissions.
Cap and trade: A market-based approach to control pollution. A central authority (usually
governmental) sets a limit or ceiling on the volume of emissions that can be released. This limit
or cap is allocated or sold to companies as emission permits. These can be bought and sold
between companies.
CO2eq: A measure used to compare the emissions from different greenhouse gases based on
their global warming potential. The carbon dioxide equivalent for a gas is derived by multiplying
the tons of the gas by its global warming potential.
Conference of the Parties (COP): Countries who sign up to the UNFCCC are known as
‘Parties’. These parties meet annually to assess progress in dealing with climate change.
Cumulative emissions: The total amount of emissions released over a given time (usually
expressed in tonnes). Ultimately this is the primary determinant of any increase in global
temperature.
PPM: Parts per million. This is a measure of the concentration of carbon dioxide in the
atmosphere. In 2014, for the first time in human history, the concentration of carbon dioxide in
the atmosphere reached 400 ppm – an increase from a pre-industrial average of around 280
ppm.
Radiative Forcing: The difference in sunlight energy received by the Earth and radiated back
to space. Where more energy is received than is reflected the system warms up. A range of
human activities and natural factors contribute to radiative forcing including greenhouse gases,
water vapour, land surface albedo and solar irradiance.
Representative Concentration Pathways (RCP): Four greenhouse gas concentration
scenarios used in the IPCC Fifth Assessment Report. The four pathways describe different
possible climate futures depending on the volume of greenhouse gases emitted in future years.
Solar Irradiance: The power of solar energy reaching the top of Earth’s atmosphere.
Solar Variability: Changes in the amount of radiation from the sun. The sun has an 11-year
cycle, energy released by the sun during this cycle changes by about a tenth of a percent.
4
BACKGROUND
IPCC
The Intergovernmental Panel on Climate Change (IPCC) was established by the World
Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP)
in 1998 to provide a clear scientific view on the current state of knowledge in climate change
and its potential environmental and socio-economic impacts. The establishment of the IPCC
was endorsed by the UN General Assembly.
The IPCC is open to all member countries of the United Nations (UN) and WMO. Currently 195
countries are members of the IPCC. Governments participate in the review process and the
plenary sessions, where main decisions about the IPCC work programme are taken and reports
are accepted, adopted and approved.
The focus of the IPCC is to prepare comprehensive assessment reports about climate change
at regular intervals. The IPCC reviews and assesses the most recent scientific, technical and
socio-economic information produced worldwide relevant to the understanding of climate
change.
ASSESSMENT REPORTS
The IPCC’s First Assessment Report (FAR) was published in 1990. This report contributed to
the United Nations Framework Convention on Climate Change (UNFCCC), which was opened
for signature at the Rio de Janeiro Summit in 19921.
In 1995 the IPCC published the Second Assessment Report (SAR). This document fed into
negotiations of the Kyoto Protocol in 19972. The Third Assessment Report (TAR) was published
in 2001 and provided improved understanding about climate change processes, impacts and
mitigation options. In 2007 the Fourth Assessment Report (AR4) provided further information
on the integration of climate change with sustainable development and links between mitigation
and adaptation. AR4 fed in to the Thirteenth Conference of the Parties (COP-13) where the Bali
Action Plan (BAP) was adopted3.
The Fifth Assessment Report (AR5) sets out the current state of scientific knowledge relevant to
climate change. AR5 will comprise three Working Group reports and a Synthesis Report (SYR)
as follows:

Working Group I. Climate Change 2013: The Physical Science Basis (published
September 2013) (IPCC 2013a)

Working Group II. Climate Change 2014: Impacts, Adaptation and Vulnerability
(published March 2014) (IPCC 2014a)
1
The United Nations Framework Convention on Climate Change is an international treaty established in 1992 to
enable countries to consider what they could do to limit increases in average global temperature and cope with
those impacts of climate change that were, by then, already inevitable.
2
The Kyoto Protocol legally binds developed countries to emission reduction targets and resulted from negotiations
to strengthen the global response to climate change.
3
The Bali Action Plan set out the path for a new negotiating process designed to tackle climate change up to and
beyond 2012 and involved sections on a shared vision, mitigation, adaptation, technology and financing.
5

Working Group III. Climate Change 2014: Mitigation of Climate Change
(published April 2014) (IPCC 2014b)

Synthesis Report. Climate Change 2014: Synthesis Report (publication due November
2014).
Each Working Group report also includes a Summary for Policymakers.
AR5 uses the following terminology to describe the likelihood of the outcome:
Term
Virtually certain
Likelihood of outcome
99–100% probability
Extremely likely
95-100% probability
Very likely
90–100% probability
Likely
66–100% probability
About as likely as not
33–66% probability
Unlikely
0–33% probability
Very unlikely
0–10% probability
Extremely unlikely
0-5% probability
Exceptionally unlikely
0–1% probability
The report also ascribes a level of certainty to some of the findings, based on evaluations by the
author teams relating to the type, amount, quality, and consistency of evidence and degree of
agreement in the scientific studies considered. Confidence is expressed qualitatively using the
following qualifiers:



very low
low
medium


high, and
very high.
6
CLIMATE CHANGE 2013: THE PHYSICAL SCIENCE BASIS
(WORKING GROUP I)
The Working Group I (IPCC 2013a) contribution to the IPCC Fifth Assessment Report provides
a comprehensive assessment of the physical science basis of climate change. The report
includes a number of new aspects including:



a new set of climate change scenarios
chapters on sea level change, carbon cycle and details relating to monsoons and El Niño
increased regional detail on impacts, adaptation and mitigation interactions.
CHANGES IN THE CLIMATE SYSTEM - OBSERVATIONS
The IPCC Summary for Policy Makers (IPCC 2013b) states that:
“Warming of the climate system is unequivocal, and since the 1950s, many of the
observed changes are unprecedented over decades to millennia. The atmosphere and
ocean have warmed, the amounts of snow and ice have diminished, sea level has risen,
and the concentrations of greenhouse gases have increased.”
Table 1 summarises some of the observed changes in the climate system presented in the
IPCC AR5 Summary for Policy Makers.
Table 1 - A summary of observed changes in the climate system
Variable
Atmosphere
Ocean
Ice and snowcover
Description

The globally averaged combined land and ocean surface
temperature has increased by 0.85°C, over the period 1880–
2012.

Significant variation exists between years and between
decades within the long term warming trend.

The upper ocean (0-700 m) has warmed from 1971 to 2010
(‘virtually certain’) and warmed between the 1870s and 1971
(‘likely’).

Globally ocean warming nearer the surface (upper 75m)
increased by 0.11°C per decade over the period 1971–2010.

Reductions in the annual mean Arctic sea ice over the period
are equivalent to 3.5 to 4.1% per decade between 1979 and
2012 (‘very likely’) (See Figure 1 below).

Northern Hemisphere snow cover extent decreased 1.6% per
decade for March and April, and 11.7% per decade for June,
over the 1967–2012 period.
7
Extreme weather
Sea level
CO2 concentration
Ocean acidification

An increase in the frequency of heat waves in large parts of
Europe, Asia and Australia since 1950 (‘likely’).

An increase in the frequency or intensity of heavy
precipitation events in North America and Europe since 1950
(‘likely’).

Global mean sea level rose by 0.19 m between 1901–2010.

The mean rate of global average sea level rise was 1.7 mm
per year between 1901 and 2010, 2.0 mm per year between
1971 and 2010 and 3.2 mm per year between 1993 and 2010
(‘very likely’).

Concentrations of CO2 substantially exceed the highest
concentrations recorded in ice cores during the past 800,000
years.

CO2 concentrations have increased by 40% since preindustrial times, primarily from fossil fuel emissions and
secondarily from net land use change emissions.

The pH of ocean surface water has decreased by 0.1 since
the beginning of the industrial era (‘high confidence’).
Observed changes over time in snow cover, the extent of Arctic summer sea ice, upper ocean
heat content and sea level change are also shown in Figure 1.
Figure 1 - Observed indicators of a changing global climate (Northern Hemisphere spring
snow cover, Arctic summer sea ice extent, change in global average upper ocean heat
content, global average sea level change).
Source: IPCC 2013a Figure SPM.3
8
UNDERSTANDING THE CLIMATE SYSTEM
The report summarises observed changes in our climate system as follows:
“Human influence on the climate system is clear. This is evident from the increasing
greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed
warming, and understanding of the climate system.”
The report notes that climate models have improved since the previous IPCC analysis (IPCC,
2007), with models reproducing observed continental-scale surface temperature patterns and
trends over many decades, including the more rapid warming since the mid-20th century and
the cooling immediately following large volcanic eruptions (‘very high confidence’).

The long-term climate model simulations show a trend in global-mean surface
temperature from 1951 to 2012 that agrees with the observed trend (‘very high
confidence’).

There are differences between simulated and observed trends over periods as short as
10 to 15 years (e.g., 1998 to 2012).

The observed reduction in surface warming trend over the period 1998–2012 as
compared to the period 1951–2012, is due in roughly equal measure to a reduced trend
in radiative forcing and a cooling contribution from internal variability, which includes a
possible redistribution of heat within the ocean (‘medium confidence’).

The reduced trend in radiative forcing (see glossary) is primarily due to volcanic eruptions
and the timing of the downward phase of the 11-year solar cycle.
CAUSES OF CLIMATE CHANGE
The report considers the factors that are causing climate change and suggests that “It is
extremely likely that human influence has been the dominant cause of the observed warming
since the mid-20th century.”
The report states that:

Changes in total solar irradiance have not contributed to the increase in global mean
surface temperature over the period 1986 to 2008 (‘high confidence’).

The 11-year cycle of solar variability influences decadal climate fluctuations in some
regions (‘medium confidence’).
FUTURE GLOBAL AND REGIONAL CLIMATE CHANGE
According to the report “Continued emissions of greenhouse gases will cause further warming
and changes in all components of the climate system.”
Four scenarios are identified in the AR5 report (Table 2). The scenarios are called
Representative Concentration Pathways (RCPs) and relate to the approximate total radiative
forcing in year 2100 relative to 1750. This is the difference between the amount of energy
received by the Earth from the sun and radiated back to space.
9
Table 2 - A summary of the emission concentrations associated with the four scenarios
identified in the AR5 report
Scenario
Description
RCP2.6
Radiative forcing peaks and
declines by 2100
Radiative forcing stabilises by 2100
RCP4.5
RCP6
RCP8.5
Radiative forcing increases beyond
2100
Radiative forcing increases beyond
2100.
CO2 equivalent
concentrations (ppm
by 2100)4
475
630
800
1313
On the basis of these four scenarios projections of mean surface temperature changes and
mean sea level rise are similar to those set out in AR4. Depending on scenario the mean
surface temperature change range from 1.0 to 2.0 oC over the period 2046-2065 and 1.0 to 3.7
o
C over the period 2081-2100. The average sea level rise ranges from 0.24 to 0.3 m and 0.4 to
0.63 m over the 2046-2065 and 2081-2100 periods respectively.
Table 3 - Mean global surface temperature change and sea level rise associated with the
four scenarios included within AR5.
2046-2065
2081–2100
Mean
Mean
Global Mean Surface Temperature Change (°C)
1.0 – 2.0
1.0 – 3.7
Global Mean Sea Level Rise (m)
0.24 – 0.3
0.40 – 0.63
Table 4 and Figure 3 summarise the projected impact of the four IPCC global emission
scenarios on the climate, including an assessment of the likelihood associated with many of
these changes.
4
Prescribed CO2 equivalent concentrations used in most of the simulations
10
Table 4 - The projected impact of the four IPCC global emission scenarios (RCPs) on a
number of climate variables including temperature, extreme weather, ice, sea level and
acidification.
Variable
Temperature
Extreme weather
Description

In all but one of the emission scenarios mean global surface
temperatures are ‘likely’ to exceed 1.5°C relative to 1850 to
1900 by 2100. In two scenarios (RCP6.0 and RCP8.5) it is
‘likely’ to exceed 2°C and for RCP 4.5 ‘more likely than not’ to
exceed 2°C (Table 3).

Warming is ‘unlikely’ to exceed 4°C for RCP2.6, RCP4.5 and
RCP6.0 (‘high confidence’) and is ‘about as likely as not’ to
exceed 4°C for RCP8.5 (‘medium confidence’).

Estimates of ocean warming in the top one hundred metres
range from 0.6°C (RCP2.6) to 2.0°C (RCP8.5) by 2100.

The Atlantic Meridional Overturning Circulation (AMOC) will
weaken over the 21st century (very likely) however it is ‘very
unlikely’ that the AMOC will undergo an abrupt transition or
collapse in the 21st century for the scenarios considered.

More frequent hot and fewer cold temperature extremes over
most land areas on daily and seasonal timescales are
‘virtually certain’.

As global mean temperatures increase it is ‘very likely’ that
the frequency and duration of heat waves will increase.

Extreme precipitation events over most of the mid-latitude
land masses and over wet tropical regions will ‘very likely’
become more intense and more frequent by the end of this
century, as global mean surface temperature increases.

Globally, it is ‘likely’ that; the area encompassed by monsoon
systems will increase over the 21st century; monsoon winds
will weaken and monsoon precipitation intensify.
11
Ice
Sea Level
Acidification

Predicted reductions in Arctic sea ice by the end of the 21st
century range from 43% to 94% in September and from 8% to
34% for in February depending on scenario (medium
confidence).

By the end of the 21st century, the global glacier volume,
excluding glaciers on the periphery of Antarctica, is projected
to decrease by 15 to 55% (RCP2.6), and 35 to 85% for
RCP8.5 (medium confidence).

The area of Northern Hemisphere spring snow cover is
projected to decrease by 7% for RCP2.6 and by 25% in
RCP8.5 by the end of the 21st century for the model average
(medium confidence).

Global mean sea level rise for 2081−2100 relative to 1986–
2005 will likely be in the ranges of 0.26 to 0.55 m in the
lowest scenario and 0.45 to 0.82 m in the highest scenario
(medium confidence).

Sea level rise will not be uniform. By the end of the 21st
century, it is ‘very likely’ that sea level will rise in more than
about 95% of the ocean area. About 70% of the coastlines
worldwide are projected to experience sea level change
within 20% of the global mean sea level change.

Ocean acidification is predicted to increase and (Figure 2).
12
Figure 2 – Modelled global annual mean surface temperature, Northern Hemisphere
September sea ice extent, and global mean ocean surface pH for the period 1950 to 2100
Source: IPCC 2013a Figure SPM.7
LIMITING GLOBAL TEMPERATURE RISE
The scale of global temperature rise will depend on the total amount of greenhouse gas
emissions released into the atmosphere. This concept is sometimes referred to as either the
area under the curve or as cumulative emissions. Figure 3 highlights the corresponding
temperature increase by 2100 as it relates to four different cumulative emission scenarios
(RCP2.6, RCP4.5, RCP6.0 and RCP8.5).
13
Figure 3 - Projections of global mean surface temperature increase in response to
cumulative total global CO2 emissions
Source: IPCC 2013a SPM.10
The report sets out the total amount of carbon dioxide (in gigatonnes of carbon dioxide GtC) that
could be released if climate warming is to be limited to less than 2°C above the 1861–1880
period. The report provides this information on the basis of three different probabilities of
achieving this warming limit: 33%, greater than 50% and greater than 66% (Table 5)
Table 5 - Cumulative CO2 emissions associated with different probabilities of limiting
warming to 2oC.
Maximum cumulative CO2 emissions (GtC)
33%
Excluding non-CO2
radiative forcing
1560
Including non-CO2
radiative forcing
880
>50%
1210
840
>66%
1000
800
Probability
14
The AR5 report notes that cumulative CO2 emissions lower than those set out in Table 5 would
be required to:

Achieve a lower warming target.

Have a greater likelihood of remaining below a specific warming target

Account for the warming effects of increases in non-CO2 greenhouse gases, reductions
in aerosols, or the release of greenhouse gases from permafrost.
By 2011 541 GtC were emitted. On the basis of the four scenarios used in AR5 the report
provides an assessment of the cumulative CO2 emissions available in the period 2012-2100
(Table 6).
Table 6 - Cumulative emission totals associated with four different RCP scenarios
Scenario
Mean
Range
Cumulative CO2 Emissions 2012–2100 (in GtC)
RCP2.6
270
140 to 410
RCP4.5
780
595 to 1005
RCP6.0
1060
840 to 1250
RCP8.5
1685
1415 to 1910
CLIMATE CHANGE 2014: IMPACTS, ADAPTATION AND
VULNERABILITY (WORKING GROUP II)
The Working Group II contribution to the IPCC Fifth Assessment Report provides a
comprehensive assessment of the impacts and risks of climate change and the scope for
adapting to it. The report details:

Observed impacts of climate change.

Approaches that are being adopted to adapt to the impacts of climate change.

Risks and opportunities resulting from climate change.
IMPACTS
The report finds that climate change is already having a range of impacts and sets out that:

Changes in precipitation or melting snow and ice are impacting on the quantity and
quality of water resources (medium confidence).

The geographic range, seasonal activity, migration pattern and abundances of many
terrestrial, freshwater and marine species have changed.

A greater number of studies report negative impacts of climate change on crop yields
rather than positive impacts. In particular reduced wheat and maize yields have been
observed in many regions.
15

The burden of ill-health from climate change is relatively small compared with other
causes. Mortality relating to heat has increased and relating to cold has decreased.

Poor people are especially vulnerable to climate change.

The impacts of recent climate-related extremes, for example heat waves, droughts,
floods and cyclones highlight that many human systems and some ecosystems are very
vulnerable.

Hazards posed by climate change can add to other challenges to impact of livelihoods.

By damaging assets that can support adaptation, for example infrastructure and natural
resources, violent conflict can increase vulnerability to climate change.
ADAPTATION APPROACHES
WGII reports that progress is being made in incorporating adaptation into planning processes,
experience in the public and private sector and within communities is growing and governments
are beginning to prepare adaptation plans and policies. Table 5 summarises some approaches
to adaptation in different regions of the world as set out in WGII.
Table 7 - Examples of climate change adaptation responses in different regions of the
world.
Region
Nature of adaptation responses

National governments developing governance systems.

Vulnerability being reduced through adjustments in technologies and
infrastructure, the implementation of ecosystem approaches,
implementation of public health measures.

Adaptation policy developed across multiple levels of government.

Some adaptation planning reflected in coastal and water
management, land planning and disaster risk management.

Mainstreaming climate adaptation into subnational development
planning. In some areas.

Actions include warning systems, water resource management
approaches and coastal reforestation of mangroves.
Australasia

Planning associated with sea-level rise and reduced water availability
becoming adopted.
North
America

Incremental adaptation planning at government level.

Proactive adaptation in areas like energy and public infrastructure.
Central &
South
America

Ecosystem-based adaptation approaches including protected areas
and community management of natural areas.

Approaches being adopted in the agricultural sector in some areas
include the use of resilient crop varieties and integrated water
resource management.
Africa
Europe
Asia
16
Figure 4 - Global impacts attributed to climate change including an indication of the confidence with which the impacts have been
attributed to climate change.
Source IPCC 2014, Figure SPM.2
17
RISKS, OPPORTUNITIES AND ADAPTATION POTENTIAL
The Working Group II report notes that greater warming will increase the likelihood of “severe,
pervasive, and irreversible impacts” and that limiting the rate and magnitude of climate change
will reduce the impacts. The report also sets out the particular risks that each sector faces and
the potential within these sectors for adaptation. Table 8 summarises some of this information.
ADAPTATION PRINCIPLES AND PATHWAYS
WGII summarises a number of principles for effective adaptation and pathways to increase
climate resilience. These principles include:

Pursuing approaches that reflect and integrate actions across a range of levels –
national, sub-national and local governments, the private sector, communities and
individuals.

Reducing vulnerability to current climate variability as a way of increasing resilience to
future change.

Utilising economic instruments (e.g. public private finance partnerships, loans, resource
pricing, charges and subsidies) to support adaptation by providing incentives.

Drawing on synergies between responses aimed at reducing emissions with those
focused on adaptation and managing trade-offs.
The report highlights that the scope for pursuing climate-resilient pathways in the future is
related to the success of efforts to reduce emissions given that mitigation would reduce the rate
and scale of warming and increase the time available for adaptation noting that “Delaying
mitigation actions may reduce options for climate-resilient pathways in the future.”
18
Table 8 - A summary of some of the risks and potential adaptation responses by sector.
Sector
Freshwater:
Risks/adaptation potential
 Greater proportion of global population at threat from
water scarcity and major river flooding.

Water resources at high latitudes set to increase.

Water quality set to reduce and pose a threat to
drinking water quality.

A “large fraction” of terrestrial and freshwater species
face an increased risk of extinction during and beyond
21st century.

Under mid- and high-range emission scenarios many
species will be unable to track suitable climates.

Interventions like maintenance of genetic diversity,
assisted species migration and dispersal and
reduction of other stressors can reduce risks of
impacts and increase capacity of ecosystems to
adapt.
Coastal systems and lowlying areas

Adverse impacts including submergence, coastal
flooding and coastal erosion set to result from sealevel rise through the 21st century and beyond.
Marine systems

Fisheries catch potential projected to increase, on
average, at mid and high latitudes (high confidence)
and decrease at tropical latitudes (medium
confidence).

Under medium to high emission scenarios, ocean
acidification poses significant risks to marine
ecosystems, especially for polar ecosystems and coral
reefs.
Food security and food
production systems

Without adaptation major crop production (wheat, rice
and maize) in tropical and temperate regions is
predicted to reduce.
Urban areas

People in urban areas are set to be at threat from a
range of factors including heat stress, extreme
precipitation, flooding, landslides and water scarcity.

Improving the provision of basic services, quality of
housing and building resilient infrastructure could
reduce vulnerability.
Terrestrial and freshwater
ecosystems
19
Rural areas
Economic sectors and
services
Human health
Human security
Livelihoods and poverty

Major impacts in rural areas associated with water
availability and supply, food security and agricultural
incomes expected.

Poor people in rural areas likely to be particularly
impacted.

Potential for rural considerations to be reflected in
adaptation measures associated with agriculture,
water, forestry and biodiversity.

Reduced energy demand for heating and increased
demand for cooling.

Increase in losses associated with more
severe/frequent weather events.

Significant uncertainty in economic impacts.

Increases in ill-health in many regions, especially
developing countries with low income to be expected
throughout the 21st century (examples include an
increase in the likelihood of disease and death
associated with more intense heat waves and undernutrition as a result of diminished food production in
poor regions).

Some reduction in cold related mortality.

Overall severity and magnitude of negative impacts
expected to outweigh positive impacts over the 21 st
century.

Vulnerability can be reduced through improvements in
public health care, greater disaster response capacity
and alleviating poverty.

Increase in displacement of people expected over the
21st century.

Opportunities to decrease vulnerability include
increasing opportunities for mobility.

Over the 21st century impacts are projected to “slow
down economic growth, make poverty reduction more
difficult, further erode food security and prolong
existing and create new poverty traps”.

The impact of climate change is expected to
exacerbate poverty in most developing countries.

Possibilities to increase resilience include insurance
programs, social protection measures and disaster
risk management.
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CLIMATE CHANGE 2014: MITIGATION OF CLIMATE CHANGE
(WORKING GROUP III)
The Working Group III contribution to the IPCC’s Fifth Assessment Report provides a
comprehensive assessment of the scientific, technological, environmental, economic and social
aspects of climate change mitigation. The report includes an assessment of a range of
mitigation options and the social impacts of different mitigation policies.
EMISSIONS TRENDS
Figure 5 shows the source of global greenhouse gas emissions by sector in 2010. The four
largest sources of emissions are electricity and heat production, emissions from agriculture,
forestry and land use (AFOLU), industry and transport. Emissions from electricity and heat are
further broken down to reflect how the electricity and heat are consumed and these are
sometimes referred to as “indirect” emissions.
Figure 5 - Global greenhouse gas emissions by sector
Source: IPCC 2014b, Figure SPM.2
Figure 6 shows changes in greenhouse gas emissions between 1970 and 2010. Between 2000
and 2010 emissions of greenhouse gas emissions have increased by 1.0 Gt CO2 per year,
equivalent to 2.2% per year. This compares to an increase of 0.4 Gt CO2 per year between
1970 and 2000 (1.3% per year).
Since 2000 GHG emissions have increased in all sectors except for agriculture, forestry and
other land use.
Emissions of carbon dioxide from the combustion of fossil fuels and industrial processes are
responsible for 78% of the total increase in GHG emissions between 1970 and 2010. CO 2
emissions from fossil fuels increased by a further 3% between 2010 and 2011 and 1-2%
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between 2011 and 2012.
In 1970 the cumulative CO2 emissions total from fossil fuel combustion, cement production and
flaring since 1750 were estimated at 420 Gt CO2. By 2010 the cumulative total had increased
by a factor of three to 1300 Gt CO2.
Figure 6 Global anthropogenic greenhouse gas emissions between 1970 and 2010
Source IPCC 2014b Figure SPM.1
Key: CO2 from fossil fuel combustion and industrial processes; CO 2 from Forestry and Other Land Use (FOLU);
methane (CH4), nitrous oxide (N2O), fluorinated gases covered under the Kyoto Protocol (F-Gases). The right side
of the figure indicates associated uncertainties with emissions of each these gases as indicated by error bars.
The report cites economic growth and population growth as the two most significant drivers of
increasing CO2 emissions from fossil fuel combustion. This increase outstrips reductions from
improvements in energy efficiency and the authors state that:
“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.”
EMISSION REDUCTION PATHWAYS
According to the WGIII report mitigation scenarios that are ‘likely’ to limit warming caused by
GHG emissions to less than 2o degrees above pre-industrial levels are ‘characterised’ by
atmospheric concentrations of around 450 ppm CO2eq in 2100. Mitigation scenarios in which
CO2 concentrations reach 530 to 650 ppm CO2eq by 2100 are ‘more unlikely than likely’ to keep
temperature change below 2oC, and those where CO2 concentrations reach 650 ppm CO2eq by
2100 are ‘unlikely’ to limit temperature change to below 2 oC.
Scenarios resulting in atmospheric concentrations of CO2 equivalent of 450 ppm by 2100 are
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characterized by reductions in global GHG emissions of 40 to 70% in 2050 compared to 2010
and near zero or below zero in 2100. Such scenarios are also characterised by rapid increases
in energy efficiency, more than tripling the share of zero and low carbon energy supply by 2050.
The report notes that those mitigation scenarios associated with achieving 450 ppm CO2 (and
many associated with achieving 500 to 550 ppm) in 2100 typically include a period when CO2
concentrations peak above this level and rely on the extensive deployment of technology that
would remove emissions from the atmosphere. Such technology includes combining biomass
as an energy source with carbon capture and storage and the report does note that the
availability and scale of such approaches are uncertain.
The WGIII assessment also highlights that estimated global GHG emissions levels in 2020
based on emission cuts pledged at Cancún (the ‘Cancún Pledges’) are “not consistent with costeffective long-term mitigation trajectories that are at least ‘as likely as not’ to limit temperature
change to 2oC relative to pre-industrial levels” and are “broadly consistent with cost-effective
scenarios that are likely to keep temperature change below 3 oC relative to pre-industrial levels.”
The authors suggest that delays to mitigation efforts will make the transition to low emission
levels over the longer term more challenging, noting that:
“Delaying mitigation efforts beyond those in place today through 2030 is estimated to
substantially increase the difficulty of the transition to low longer-term emissions levels
and narrow the range of options consistent with maintaining temperature change below
2oC relative to pre-industrial levels (high confidence).”
According to the report cost-effective mitigation scenarios that make limiting temperature to less
than 2oC and are ‘as least as likely as not’ tend to be characterised by annual GHG emissions in
2030 of 30 to 50 GtCO2eq.
MITIGATION COSTS
The Working Group III report highlights that significant variations exist in the estimates of
aggregate economic costs of mitigation with estimates very sensitive to assumptions, model
design and the details included within scenarios. However, on the basis of a number of
assumptions, scenarios that result in atmospheric CO2eq concentrations of around 450 ppm by
2100 result in reductions in the global consumption of goods and services of between 3% and
11% in 2100 (compared to baseline scenarios of growth of between 300% and 900%). The
assessment concludes that this equates to an annual reduction in growth of between 0.04% and
0.14%.
23
SECTORS
Table 9 summarises the scale and scope for emissions reduction in some significant
sectors.
Sector
Energy
supply
Transport
Emission reduction potential – scale and scope
 Decarbonisation of electricity generation is a “key component” of costeffective mitigation strategies that achieve low CO2 stabilization levels
(430-530 ppm CO2eq). Under these strategies the share of low-carbon
electricity supply increases from approximately 30% to over 80% by
2050 and fossil fuel power generation without CCS is phased out
almost entirely by 2100 in most scenarios.

Significant improvements in performance and cost reductions in many
renewable technologies achieved since the publication of AR4 has
supported deployment at scale.

Many renewable technologies continue to require support to boost their
market share.

Scope to reduce GHG emissions from energy supply by replacing coalfired power plants with very efficient gas combined-cycle power plants
or combined heat and power (subject to availability of natural gas and
ensuring that emissions associated with extraction and supply are low
or mitigated.

Carbon capture and storage (CCS) technology could play a role in
reducing GHG emissions of fossil fuel plants, however regulatory
incentives and or high carbon prices or direct financial support likely
required.

Many low CO2 concentration stabilisation scenarios involve bioenergy
combined with CCS (BECCS).

Efficiency and vehicle performance improvements range from 30-50%
in 2030 relative to 2010.

Modal shifts have the potential to reduce transport GHG emissions by
20-50% in 2050 compared to baseline.

The challenges associated with energy storage and the low energy
density of low-carbon transport fuels constrain the options and speed
for decarbonising the transport sector.
24
Buildings
Industry
Agriculture,
Forestry and
Other Land
Use
Human
Settlements,
Infrastructure
and Spatial
Planning

Improvements in technologies, knowledge and policies provide
opportunities to stabilise or reduce energy use in the building sector by
2050.

The adoption of very low energy building codes important for new
buildings and retrofit programmes for countries with established stock
have a strong role to play.

Lifestyle and behavioural changes for developed countries could
reduce energy demand by up to 50% of present levels by mid-century.

Reducing emissions from buildings provide significant additional
benefits for example energy security, tackling fuel poverty and
providing employment opportunities.

The use of best available technologies has the potential to improve the
energy efficiency of the industry sector by around 25% compared to the
current level.

Further emission reductions could be achieved through more efficient
material use, recycling and re-use of materials and reductions in
demand.

Afforestation, reducing deforestation and sustainable forestry
management provide cost effective mitigation options for forestry.

Cost-effective mitigation options for agriculture include cropland and
grazing land management and restoration of organic soils.

Bioenergy can play an important role in reducing emissions. However
issues including the sustainability of practices and efficiency of systems
need to be considered and barriers to the deployment at scale include
concerns about GHG emissions from land and biodiversity
conservation.

Cities in Annex I countries tend to have lower levels of energy use per
capita compared to the national average, and those cities in Annex II
tend to have higher levels.5

Opportunities exist to address emissions from urban areas in the
coming decades as a result of the development of many of these areas
during this time.

Successful approaches to mitigation require the integration of policies,
for example to co-locate high residential and high employment density
areas, invest in public transport and demand management measures.
5
Annex 1 countries include those industrialised countries that were members of the Organisation for Economic Co-operation
and Development (OECD) in 1992, plus countries with economies in transition, including the Russian Federation, the Baltic
States, and several Central and Eastern European States. Annex II countries comprise those countries that were members of
the OECD but exclude economies in transition. They are required to provide financial support to enable developing countries to
reduce their emissions and adapt to climate change.
25
NATIONAL MITIGATION STRATEGIES AND POLICIES
The WGIII report highlights that despite a significant increase in national and sub-national plans
and strategies aimed at curbing climate emission there has “not yet been a substantial deviation
in global emissions from the past trend.” The report also suggests that policies that are sector
specific are more widespread than those that are economy-wide. The authors suggest that:
“..most economic theory suggests that economy-wide policies for the singular objective of
mitigation would be more cost-effective than sector-specific policies, since AR4 a growing
number of studies has demonstrated that administrative and political barriers may make
economy-wide policies harder to design and implement than sector-specific policies.”
The report also considers the impact of cap and trade systems for greenhouse gas emissions.
A cap and trade approach works by setting a limit is set on the amount of greenhouse gases
that can be emitted by specific sectors (e.g. power stations). Within the limit companies can
receive or buy emission allowances and trade them as needed. The report suggests that the
impact of such systems has been limited because the caps have been set at relatively high
levels. The authors note that in some countries, tax-based policies designed to curb
greenhouse gas emissions have helped reduce the amount of emissions released per unit of
economic activity. They also refer to projections that reductions in global emissions by midcentury could be achieved through the removal of fossil fuel subsidies in all countries.
RESPONSES TO THE PUBLICATION OF AR5
Some individuals and organisations including the Global Warming Policy Foundation (GWPF)
have challenged the findings and conclusions of the IPCC AR5 report, however their views are
not shared by the majority of climate scientists. A wide range of politicians, scientists and
environmental bodies responded to the publication of the AR5 Working Group reports.
Commenting on the release of the WGI report on the physical science of climate change EU
Commissioner for Climate Action Connie Hedegaard noted the need to follow the science and
Europe’s role in cutting emissions (European Commission 2013):
“The issue is not whether to believe in climate change or not. The issue is whether to
follow science or not. The day when all scientists with 100% certainty warn you against
climate change, it will be too late. If your doctor was 95% sure you had a serious
disease, you would immediately start looking for the cure. Why should we take bigger
risks when it's the health of our planet at stake? Europe will continue to lead the fight
against climate change. We have ambitious legislation in place. We are reducing our
emissions considerably, expanding renewables and saving energy. And we are getting
ready for the next step: climate and energy targets for 2030 that the Commission will
present before the end of the year. The reality is that others are now following suit.
Europe will continue to demand more action from all the emitters.''
The UK Secretary of State for Energy and Climate Change, Edward Davey set out the need to
take action (DECC 2013):
“The message of this report is clear - the Earth’s climate has warmed over the last
century and man-made greenhouse gases have caused much of that global warming.
26
The gases emitted now are accumulating in the atmosphere and so the solutions must be
set in motion today. The risks and costs of doing nothing today are so great, only a
deeply irresponsible government would be so negligent.”
Paul Wheelhouse, Scottish Government Minister for Environment and Climate Change set out
the need for a global deal on climate change (Scottish Parliament 2013):
“The IPCC report sends a stronger than ever warning that human activity is changing the
global climate and that reducing global greenhouse gas emissions is the only way of
limiting the extent of future climate change. It also shows that without global action,
surface temperature could increase by up to 4.5°C and the sea level by up to 0.82m by
the end of the century… given the IPCC’s warning, Scotland’s actions alone are not
enough and we need the rest of the United Kingdom, our European neighbours and
indeed all countries to share our ambition. We want an ambitious global deal on climate
change to be agreed in 2015 and have been calling for the European Union to raise its
pre-2020 emissions target.”
Professor David MacKay FRS, Chief Scientific Advisor to the Department of Energy and Climate
Change highlighted the risks of delaying action (DECC 2013):
“One important message of this new report is that, while there remains some uncertainty
about the precise sensitivity of the climate to greenhouse gas emissions, the impact on
climate is largely determined by the cumulative total of humanity’s carbon emissions.
This means that waiting a decade or two before taking climate change action will
certainly lead to greater harm than acting now.”
James Curran, Chief Executive of the Scottish Environment Protection Agency (SEPA) noted
the risks and dangers of positive feedback (SEPA 2013):
“…this report crucially states that there is now high confidence that feedback between
climate and the Earth’s own carbon cycle is positive. That is so very dangerous: it means
as climate change progresses, polar ice disappears, which means sunshine can heat the
revealed land and oceans more effectively; and as permafrost melts, the soggy soils can
release methane into the atmosphere; as oceans become acidic, plankton don’t soak up
carbon as much; as forests or peatlands die back, they don’t absorb carbon, but in fact
release it. That’s the danger zone we must keep away from, and nations around the
world have agreed we step into that danger zone when planetary temperature has risen
by about 2oC.”
The UK Committee on Climate Change (UKCCC) set out the scale of the change required to our
energy systems if the two-degree target is to be hit, UKCCC member Professor Jim Skea
(UKCCC 2013) said:
“Hitting the two-degree target has not been ruled out, but the IPCC has concluded in its
report that major changes would be needed to energy systems, requiring technological
and institutional change on a massive scale.
“This could imply a tripling or quadrupling, by 2050, of cleaner electricity sources such as
renewables, nuclear or fossil fuels, along with carbon capture and storage, and the
aggressive pursuit of energy efficiency opportunities.”
Global responses include the United States. Commenting on the release of the Working Group
27
II Report Secretary John Kerry (US Embassy 2014) said:
“Read this report and you can't deny the reality: Unless we act dramatically and quickly,
science tells us our climate and our way of life are literally in jeopardy. Denial of the
science is malpractice.
There are those who say we can’t afford to act. But waiting is truly unaffordable. The costs of inaction
are catastrophic.”
In October 2013 the House of Commons Energy and Climate Change Committee launched an
inquiry6 into the Fifth Assessment Report. The inquiry considered the latest conclusions of the
IPCC, how robust the conclusions are and their impact on national and international policy
making. In July 2014 the Committee published their report (House of Commons 2014).
Amongst their conclusions the Energy and Climate Change Committee concluded that:
“the WGI contribution to AR5 is the best available summary of the prevailing scientific
opinion on climate change currently available to policy-makers. Its conclusions are
derived with a high confidence from areas of well understood science. Uncertainty
remains in a small number of important areas but these are diminishing….The overall
thrust and conclusions of the report are widely supported in the scientific community and
summaries are presented in a way that is persuasive to the lay reader.”
UNFCCC PROCESS – NEXT STEPS
At the United Nations Climate Change Conference in Durban in 2011 (Conference of the Parties
17) those countries signed up to the UNFCCC agreed to develop a new legal agreement to be
adopted in Paris in late 2015 to cover all countries from 2020 and scale up efforts before 2020
to curb emissions.
In parallel those signatories to the UNFCCC agreed to review the adequacy of the 2°C upper
limit of acceptable warming and progress towards limiting warming in line with this. The Director
for Implementation Strategy of the UN Climate Change Secretariat has already noted (UNFCCC
2013) that
“We know that the sum total of on-going efforts to limit warming will not add up to what is
needed to bend the curve and mankind is not on track to limit warming to 2°C.”
AR5 provides an important resource that is likely to be drawn on in informing and developing the
next steps of the UNFCCC process including the development of a new agreement on climate
action over the coming year for consideration at a Conference of the Parties meeting in 2015 in
Paris.
6
http://www.parliament.uk/business/committees/committees-a-z/commons-select/energy-and-climate-changecommittee/inquiries/parliament-2010/the-ipcc/
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SOURCES
DECC. 2013. Media release: https://www.gov.uk/government/news/response-tointergovernmental-panel-on-climate-change-ipcc-fifth-assessment-report-ar5-the-latestassessment-of-climate-science [Accessed 15th May 2014]
European Commission. 2013 Media release: http://europa.eu/rapid/press-release_MEMO-13827_en.htm [Accessed 15th May 2014]
House of Commons. 2014 Energy and Climate Change - First Report. Intergovernmental
Panel on Climate Change Fifth Assessment Report: Review of Working Group I contribution
[Accessed 23rd September 2014].
IPCC. 2007 Climate Change 2007 The AR4 Synthesis Report. Available at:
http://www.ipcc.ch/publications_and_data/publications_and_data_reports.shtml [Accessed 8th
May 2014].
IPCC. 2013a Climate Change 2013 The Physical Science Basis. IPCC Working Group I
contribution to AR5. http://www.climatechange2013.org/ [Accessed 8th May 2014]
IPCC. 2013b Climate Change 2013 The Physical Science Basis. IPCC Working Group I
contribution to AR5. Summary for Policymakers. Available at:
http://www.climatechange2013.org/images/report/WG1AR5_SPM_FINAL.pdf [Accessed 8th
May 2014].
IPCC 2014a Climate Change 2014. Impacts, Adaptation and Vulnerability. IPCC Working
Group II contribution to AR5. Available at: http://ipcc-wg2.gov/AR5/ [Accessed 8th May 2014]
IPCC 2014b Climate Change 2014. Mitigation of Climate Change. IPCC Working Group III
contribution to AR5. Available at: http://www.mitigation2014.org/ [Accessed 8th May 2014]
SEPA. 2013. SEPA View IPCC Latest Climate Report: our CEO’s views. Available at
http://www.sepaview.com/2013/09/ipcc-latest-climate-report-our-ceos-views [Accessed 15th
May 2014]
Scottish Parliament. 2013. Official Report 1st October 2012. Available at
http://www.scottish.parliament.uk/parliamentarybusiness/28862.aspx?r=8893 [Accessed 15th
May 2014].
UKCCC. 2014 Renewable solution needed: our response to the third IPCC report. Available at:
http://www.theccc.org.uk/blog/renewable-solution-needed-our-response-to-the-third-ipcc-report/
[Accessed 15th May 2014].
UNFCCC. 2013. Opening Statement 12th Session of IPCC Working Group 1. Available at
http://unfccc.int/files/press/statements/application/pdf/20132309_ht_ipcc.pdf [Accessed 15th
May 2014].
US Embassy. 2014. Statement by Secretary Kerry – Release of Intergovernmental Panel on
Climate Change Working Group 2 Report. Available at:
http://iipdigital.usembassy.gov/st/english/texttrans/2014/03/20140331297180.html#axzz3En8Ay
OAQ [Accessed 30th September 2014]
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