Download Science aspects of the 2°C and 1.5°C global goals in the Cancun

 LDC paper series Science aspects of the 2°C and 1.5°C global goals in the
Cancun Agreements
Bill Hare, Michiel Schaeffer, Marcia Rocha
November, 2011
1 Acknowledgements
This document is an output from a project funded by the UK Department for International
Development (DFID) for the benefit of developing countries. However, the views expressed and
information contained in it are not necessarily those of or endorsed by DFID, which can accept no
responsibility for such views or information or for any reliance placed on them.
The authors would like to thank Matthias Mengel
(Potsdam Institute for Climate Impact Research (PIK), Germany)
for his review comments.
Climate Analytics Telegrafenberg A26 14473 Potsdam Germany P: +49 331 288 2481 F: +49 331 288 2478 www.climateanalytics.org 2 Summary In the international climate negotiations, long-term global targets can serve as a guideline for
policy decisions on mitigation. However, under any long-term global target, the impacts of
climate change are not equally distributed over countries. The evaluation of a global target
for limiting global warming needs to take into account this heterogeneity and the interests of
countries that take the bigger share of impacts.
This paper reviews the scientific literature on impacts for 1.5 and 2°C warming levels
with focus on risks for LDCs. We summarize observed impacts in LDCs that have been
related to global mean temperature and provide an overview of projected future changes. This
comprises a wide range of impacts along the causal chain of global warming: sea level rise,
extreme events (e.g. droughts, floods, tropical storms), impacts on natural ecosystems,
economic impacts (e.g. on agriculture, fisheries, tourism), food and water security, and
health.
In Africa, for example, malnutrition combined with higher Malaria incidence, which is a
climate sensitive disease, may lead to increased mortality rates. Furthermore, ecosystems and
biodiversity will face impoverishment, which may be accompanied by the loss of important
ecosystem services necessary for the maintenance of livelihoods and human societies over
time. In Bangladesh, the strongest increase per unit of warming in annual-mean inundated
area due to floods and sea-level rise is estimated to occur between 1.5 and 2°C warming.
The continuous effort made by the scientific community has identified risks associated
with human-induced global temperature increase at a geographic and sectoral scale most
relevant to LDCs. The findings show a negative balance for LDCs at current levels of
warming and overwhelmingly negative at levels expected on the coming century.
At the 2010 climate conference in Cancun the international community agreed to issue a
periodic review that examines the adequacy of the long-term goal and overall progress to
achieving it. So far, the focus lies on temperature goals, with a limit of 2°C increase above
pre-industrial and the option to revise it to 1.5°C. If the reviews need to take account of the
interests of LDCs, we conclude that the information inputs to the periodic review need to
include assessments on a time and spatial scale suitable for reflecting LDCs circumstances
and vulnerabilities to the adverse effects of climate change.
3 1) Introduction Global temperature targets, such as staying below 2 or 1.5°C, guide policy makers in defining
action to prevent dangerous anthropogenic interference with the climate system. However,
although constrained by the average temperature increase relative to pre-industrial levels,
impacts of climate change vary widely in frequency and intensity across regions. The
regional differences in the level of vulnerability need to be taken into account in the decisionmaking process, and better scientific knowledge of the potential local impacts of climate
change is therefore constantly required.
This briefing aims on reviewing the implications of different levels of warming for
climate risks and impacts. The focus will be on the risk and impact indicators most relevant
to LDCs, while taking into account the heterogeneity within the group. The latter implies that
a wide range of impacts needs to be addressed, including among others food and water
security, climate extreme events (e.g. droughts, floods, tropical storms), sea-level-rise, health,
economic impacts (e.g. on agriculture, fisheries, tourism) and impacts on natural ecosystems.
Additionally, the paper will address the issues of probabilities of staying below the warming
targets of 2°C and 1.5°C.
To put the warming targets discussed in this paper into perspective Figure 1 shows the
effect of assumptions of future emissions on the level of warming over the 21st century. The
red pathway (top-line) shows projected emissions under a “business-as-usual“ estimate
without climate policy beyond current policy. The minimum warming possible due to laws of
physics (“Geophysical inertia”) corresponds to the fully hypothetical case that all global
emissions were cut to zero in the year 2016, leading to an increase of roughly only 1°C
relative to pre-industrial levels by 2100 (dashed black line). The purple line (second line from
top) shows the impact of currently proposed emission reductions pledged by Parties to the
UNFCCC and is technically and economically highly feasible. This is not a minimum and
therefore this does not imply that lower pathways are not feasible. In fact, other feasible
energy-economic mitigation scenarios allow warming to be held below 1.5°C and 2°C with
high probability (blue and green lines in Figure 1), possibly after a temporary overshoot in
the case of 1.5°C.
Figure 1 Global-­‐mean warming trajectories resulting from various emission pathways to illustrate the levels of warming that are plausible in the 21st century. Source: Climate Analytics. 4 Two related papers accompany this overview of warming-level impacts: the briefing
“Periodic Review: Background and Analysis” which focuses on how the Periodic Review
mentioned in the Cancun Agreements links back to the negotiations and the briefing
“Mitigation - pledges, impacts and effects on LDCs” which addresses general mitigation and
feasibility of achieving emission levels, which would allow likely staying below the warming
targets of 2°C and 1.5°C.
2) Assessment of the target options on the table: link to global-­‐mean changes A number of different types of global targets have been proposed for use in international
climate policy. These include global-mean warming targets, greenhouse-gas concentration
equivalent goals, carbon dioxide concentration levels, and emissions in different years such
as 2020 and 2050. In this section we briefly review some of these and how they are related.
Identification of a global warming goal has long been recognised as not a purely scientific
issue and requires political judgments as to the level of acceptable risk and damages. Science
can inform policymakers about these risks and damages at different levels of global-mean
warming, greenhouse gas concentration, or other indicators.
While there is not unanimity in the scientific community about the “best” global warming
goal, it is also clear that several different measures are needed to define appropriate global
goals for climate policy. For example, a temperature goal needs to be operationalised and to
do this in a politically meaningful way means that emission levels at the global level need to
be, if not universally agreed upfront, at least met at different time frames. The same would
also apply to a greenhouse gas concentration equivalent goal. This section will not deal with
the complexities of these inter-relationships, but it will identify a number of the issues
involved.
Global-mean temperature goals
The Cancun agreements mention warming below 1.5 and 2°C above pre-industrial as
targets for the long-term goal. A major motivation for using global-mean temperature
increase as a goal is that many impacts and indicators of climate change, such as floods,
droughts and tropical storms are often closely linked to global warming, although to a
regionally highly diverse extent. The link between regionally heterogeneous impacts and
global-mean warming levels will be explored in section 3.
The goal to hold the increase in global average temperature below 2°C above
preindustrial was first called for by the European Union at Environment Ministers level in
1996i, and subsequently endorsed at Head of Government in 2004ii. Subsequent to the
conclusions of the IPCC 4th Assessment Report many vulnerable countries, including the
small island developing states and many least developed countries became concerned that the
impacts identified at a warming level of 2°C above preindustrial may be too severe.
Consequently in 2008, AOSIS and the LDCs proposed a goal of limiting warming to 1.5°C
above the preindustrial leveliii, and during 2009 more countries associated themselves with
i
“...the Council believes that global average temperatures should not exceed 2 degrees above pre-industrial level and that
therefore concentration levels lower than 550 ppm CO2 should guide global limitation and reduction efforts....” 1939th
Council meeting, Luxembourg, 25 June 1996.
ii
“The Council... ACKNOWLEDGES that to meet the ultimate objective of the UNFCCC to prevent dangerous
anthropogenic interference with the climate system, overall global temperature increase should not exceed 2ºC above preindustrial levels;...” Spring European Council 2004, 25-26 March 2004, Doc 7631/04 (ANNEX), page 29.
iii
The Alliance of Small Island States and the Least Developed Country group called for warming to be limited to 1.5°C at
the 14th Conference of the Parties to the United Nations Framework Convention on Climate Change in Poznan, Poland,
December 2008. ENB (2008) COP 14 Highlights: Thursday, 11 December 2008; www.iisd.ca/download/pdf/enb12394e.pdf.
5 this target. During 2009, pressure was mounting on many developed countries to support the
2°C goal and it was first agreed by the G8 in Italy and at the subsequent MEF meetingiv. At
Copenhagen this led to the situation where a global goal of 2°C above preindustrial was
referenced in the Copenhagen Accord, along with the understanding that this goal reviewed
with a view to strengthening it to a 1.5°C goal.
It is possible to “translate" a global mean temperature goal into intermediate emission
targets for different timeframes such as 2020 and 2050, but to do so means deciding with
what probability one wishes to achieve the temperature goal, given the uncertainties that
relate to these kinds of calculations. There is a rich scientific literature now on this, however
there remains a lack of certainty from the policy community about the level of probability
with which a temperature goal is to be achieved. Caution is therefore needed when
encountering claims that a certain level of emissions in a certain year is consistent with a
particular warming goal: often such claims are linked only to a 50% chance of meeting a
given warming goal and hence an equal chance of exceeding the goal.
Greenhouse gas concentration equivalent goals
Greenhouse gas concentration equivalent goals are sometimes called for on the basis that they
are easy to understand and measure (as one can measure carbon dioxide and other
greenhouse-gas concentrations in the atmosphere) and that it is easier to translate such
concentration goals into emission targets than it is for temperature goals. The opposite side of
this argument is that there is also substantial uncertainty in relating greenhouse-gas
equivalent concentration levels to global-mean warming. Using greenhouse-gas concentration
goals hence may in effect overlook these uncertainties. Concentration pathways as a policy
goal to avoid impacts linked to warming levels, could provide a false sense of confidence,
because one still needs temperature projections to link concentration targets to most climate
impacts - which are ultimately the motivation for most climate policy in the first place. In
addition, converting greenhouse gas concentration goals to emission pathways also has
substantial uncertainties and requires policy choices, the same as with the temperature goal.
However, advances in scientific understanding in the last decade permit qualification of
emission pathways consistent with concentration and temperature goals, the latter taking
account the full range of scientific uncertainties in our understanding of how the climate
system will respond to greenhouse gas forcing1.
Error! Reference source not found.Figure 2 below shows the relationship between
different greenhouse gas concentration stabilisation levels and the probability of exceeding
1.5, 2 and 3°C global-mean warming above preindustrial in the very long term
(“equilibrium“). This figure gives a good indication of the uncertainties involved in moving
from a greenhouse gas concentration level goal to a global-mean warming goal.
One greenhouse gas concentration equivalent goal often referred to is 450 ppm CO2-eq.
Sometimes this is said to be equivalent to a 2°C global-mean warming goal. However, it
should be noted that in the long run stabilisation at 450 ppm CO2-eq corresponds to a 60%
chance of exceeding 2°C global mean warming above the preindustrial level, i.e. worse than a
1-in-2 chance of holding warming below 2°C.
iv
Canada, France, Germany, Italy, Japan, Russia, the United Kingdom and the United States (2009) Responsible Leadership
for a Sustainable Future. http://www.g8italia2009.it/static/G8_Allegato/G8_Declaration_08_07_09_final,2.pdf and
Australia, Brazil, Canada, China, the European Union, France, Germany, India, Indonesia, Italy, Japan, the Republic of
Korea, Mexico, Russia, South Africa, the United Kingdom, and the United States (2009) Declaration of the Leaders of the
Major Economies Forum on Energy and Climate
http://www.g8italia2009.it/static/G8_Allegato/G8_Declaration_08_07_09_final,0.pdf
6 !"!#$%&'()(*&+,-#)./.)0#/0#
1.23.4&%54.#6,&)0#
Figure : The probability that temperature targets are exceeded for different levels of long-term stabilization of GHG concentrations.
Figure 2 The probability that temperature targets are exceeded in the long term for different level of long-­‐term stabilization of greenhouse-­‐gas concentrations. Source: Climate Analytics. Carbon dioxide concentration goals
Carbon dioxide concentration has also been proposed as a global warming goal. A level of
350 ppm was put forward by Jim Hansen and colleagues in 20082 as a marker on the way to
lower concentration levels. The authors argued that, in effect, 2°C warming was too risky in
the long run for many Earth systems and that safety may only be obtained in substantially
lower long-term warming levels. They proposed an initial CO2 level of 350 ppm at which
humanity should aim, but highlighted that this is still not a final safe level. Since that time a
significant NGO movement has built up, calling for a global goal of 350 ppm. As can be seen
in Figure 2, achieving this level of CO2-eq concentration would correspond to a high
probability of limiting warming to 1.5°C or below in the long term (low probability to exceed
1.5°C).
What could be confusing here is the association between carbon dioxide (CO2)
concentration itself and total greenhouse gas concentration expressed in CO2-equivalents
(CO2-eq), which takes into account the effects of all other greenhouse gases (like methane,
nitrous oxide and F-gases) and forcing agents (aerosols like sulphates, black carbon and
organic carbon). For practical purposes achieving a level of 350 ppm CO2 concentration may
be seen as equal to a greenhouse gas equivalent level of about the same 350 ppm level: other
greenhouse gases would add to the CO2-eq level, but human activities are likely to be
continually asserted with aerosol emissions, whose net effect is likely to be cooling, thereby
offsetting some of the additional non-CO2 gases. It should be emphasised that this is a rough
approximation and one would need to look at the detailed scenario to advise on specific
differences.
The increased global-mean atmospheric concentration of CO2 has direct impacts other
than warming. Uptake of CO2 by the ocean leads to acidification of the ocean near-surface
layers that sustain life and fisheries worldwide, as has been observed over the past decades35. Organisms that use calcium for growth are inhibited to do so if the water is more acid.
This affects coral reefs and all shell organisms, as well as fish species that depend on these
and hence the fisheries and tourism sectors. Recent scientific research shows that corals
around the world are likely to stop growing once atmospheric CO2 concentration rises above
about 450 ppm and will start dissolving above 550 ppm (Figure 3). If multiple stressors are
included, like higher ocean surface-water temperatures due to global warming, sea-level rise,
and deterioration in water quality, a CO2 level of below 350 ppm is required for the longterm survival of coral reefs. As Figure 3 shows, a level of emissions that holds temperature
below 2°C (orange line) with a medium probability (about 50% chance) is associated with
7 CO2 concentrations around 450 ppm in the 21st century. Global emission levels lower than
50% of 1990 levels by 2050, and negative emissions after the 2050s are required to hold
warming well below 2°C and to hold CO2 concentrations below 450 ppm to gradually let
CO2 levels decline to 350 ppm and below (blue and green lines). About such emission
reductions, see the associated CDKN paper “Mitigation - pledges, impacts and effects on
LDCs”.
Figure 3 Global atmospheric CO2 concentration is closely linked to global-­‐mean temperature increase (Figure 1), with temperatures responding to concentrations with a time delay of decades. For explanation of line coloring, see Figure 1. Source: Climate Analytics. Sea level rise
Another crucial global climate-change indicator other than temperature is global sea level
rise. A crucial difference to other key indicators is the very slow response of sea level to
changes in global temperatures. Part of sea-level rise originates from warming of the oceans
and therefore expansion of the ocean water. The full effect of this only comes about after heat
penetrates from the surface to the deep oceans, which takes decades to multiple centuries. A
major part of sea level rise up to today has been caused by this “thermal expansion”. The
other major part of sea level rise originates from melting of land-based ice masses, including
both mountain glaciers of all continents and the large polar ice sheets of Greenland and
Antarctica. Recent research shows that in particular the contribution of the polar ice sheets to
global sea level rise has accelerated in the past decade6.
Figure 4 shows how sea level rise responds if emissions were hypothetically cut to zero in
2016 (dashed line). This illustrates that even just the past emissions of the previous century
until the year of the 2015, when the review will be held, will lead to continuing sea level rise
far into the 21st century. It also shows that even the strongest global mitigation in the 21st
century will not be able to cut sea level rise by 2100 by more than half of the total (compare
dashed black line to business-as-usual in red, in which the latter includes all 21st century nonmitigated emissions). It is very important to note, however, that the half that can be avoided
can be achieved by realistic mitigation options in line with warming well below 2°C (blue
and green lines). Most importantly, only if warming is limited to well below 2°C, sea-level
rise slows down by 2100 so much that sea level has a chance to stabilize at a level well below
a rise of 2 meters or more in later centuries. By contrast, sea level rise of over 2 meters in the
next two centuries is likely both in the case of business-as-usual emissions (no mitigation)
and in the case of targeting mitigation to limit warming to below 2°C with only a “medium”
50% chance.
8 Figure 4 Global sea level rise responds to temperature changes (Figure 1) with a delay of decades to multiple 7
centuries. For explanation of line coloring, see Figure 1. Source: Climate Analytics and PIK . Global emission goals
As mentioned at the outset of this discussion a global temperature or concentration goal
needs to be operationalised ultimately through emission goals and the reference years of 2020
and 2050 have been discussed extensively to implement this.
In relation to the issue of a global 2050-emission goal, levels such as a 50% reduction by
2050 from emission levels pertaining to a recent period 1990 have been discussed extensively
over the past decade, including in the G8 contextv. Agreement on 2050 reduction goals has
however not been achieved, with the issue being left open from both the Copenhagen and
Cancun climate talks. There are several different elements to this discussion, which are
vitally important. One of these elements relates to the relationship between an emission
reduction in 2050 and the achievement of a temperature goal and the other relates to basic
equity considerations. The latter involves an understanding about the emission reductions
from different groups of countries and will be discussed briefly.
While emission levels in 2020 consistent with meeting either the 2°C or 1.5°C global
temperature goal are quite close, levels of reductions in 2050 required for each of these goals
are quite different. Halving global emissions by 2050 gives a roughly 50% chance of
exceeding 2°C in the 21st century, but about a 90% chance of still exceeding 1.5°C by 2100.
By contrast, if emissions are reduced to 80-85% below 1990 by 2020, there is only roughly
20% chance of exceeding 2°C. At this emissions level in the 2050s and strong net-negative
CO2 emissions by 2070 and beyond, the chance of exceeding 1.5°C by 2100 can be reduced
to 65%. The latter would also keep CO2 concentrations below 450 ppm and start on a
downward path towards 350 ppm.
A global 2050 emission goal is unlikely to be agreed on, however, without an
understanding on the implied relative level of emissions in Annex I and non-Annex I
countries (between developed and developing countries). This means that a 2050 emission
reduction globally of 80 to 85% from 1990 levels, which would be required to give a high
probability of limiting warming to 1.5°C ultimately, would require 95% or more reductions
from the developed countries by 2050 in order for global per capita emissions to be
v
The G8 did not agree a base year. 9 approximately equal in that yearError! Reference source not found.. Of the Annex I
countries, only the European Union has a position that comes close to this and then only at
the outer boundaries of its demands for Annex I countries (80 to 95%).
Table 1 Implications for non-­‐Annex I remission reductions by 2050 under different combinations of global and Annex I reduction targets. The column on the right shows per capita emissions by 2050 in non-­‐Annex I compared to Annex I for these target combinations. Notes: *global target assumes deforestation emissions reach zero by 2050, but no reductions in emissions by international aviation and shipping; **deforestation emissions reach zero by 2050, and emissions by international aviation and shipping return to 1990 levels by 2050. Sources: Climate Analytics, UN (2010). Global emissions Annex-­‐I emissions non-­‐Annex I emissions Non-­‐Annex-­‐I emissions per capita relative to Annex I emissions per capita (% relative to 1990) (% relative to 1990) (% relative to 1990) (rough estimate using UN (2010) population projections) -­‐50%* -­‐50%* -­‐50%* -­‐85%** -­‐80% -­‐90% -­‐95% -­‐95% -­‐20% -­‐5% 0% -­‐70% Non-­‐Annex I per cap ½ × Annex I per cap equal Non-­‐Annex I per cap 2½ × Annex I per cap equal 3) Regional climate risks and impacts at different target options Policy-makers are clearly interested not so much in an abstract global warming limit as in
identifying and avoiding severe risks and damages at local, national and regional levels.
Science has advanced a long way in associating different levels of global-mean warming with
different levels of risks, impacts and vulnerabilities, although uncertainties remain. In this
section we outline some of the considerations that may be relevant to determining what levels
of warming may be acceptable by indicating some of the results from the IPCC 4th
Assessment Report and more recent scientific literature. It is not possible to be
comprehensive in this brief summary of issues and hence what is presented below should be
seen more as a snapshot of the authors’ perceptions than an authoritative guide the
implications of a vast literature.
IPCC Fourth Assessment Report
The IPCC 4th Assessment Report (AR4) identified global warming posing a significant risk to
sustainable development in many vulnerable regions, particularly in Africa, reporting: “Very
likely that climate change can slow the pace of progress towards sustainable development.”
According to the report: “Over the next half-century, climate change could impede
achievement of the Millennium Development Goals.” For the first time, this assessment
showed a relationship between global-mean warming at different time frames and risks in
different regions. Figure 5Error! Reference source not found. provides an overview of
these risks worldwide.
Impacts of climate change on LDCs
The IPCC AR4 found the climate change is likely to threaten the achievement of the
sustainable development goals in the most vulnerable countries:
Sustainable development can reduce vulnerability to climate change, and climate change could impede nations’ abilities to achieve sustainable development pathways. It is very likely that climate change can slow the pace of progress toward sustainable development either directly through increased exposure to adverse impacts or indirectly through erosion of the capacity to adapt. Over the next half-­‐century, climate change could impede achievement of the Millennium Development Goals. 9 10 Figure 5 Selected regional impacts associated with various reductions in global greenhouse-­‐gas emissions. Source: Parry 8
et al . Global climate change has already shown observable effects on LDCs. For example, in
Ghana, increased drought and aridification, along with rising temperatures led to a decrease
in water level in the Akosombo Reservoir, causing major problems in the production of
hydroelectric power10-13. In northern African countries, water resources have been affected in
that the frequency of extreme events such as floods or extended droughts has increased14. A
direct consequence is crop loss, causing starvation of human populations, or livestock, if
alternative food sources are not available. In fact, rainfall receipts have decreased by around
15%, which threatens eastern and southern African countries dependent on rain-fed
agriculture. Anthropogenic warming has probably already produced societally dangerous
climate change by increasing poverty and vulnerability of rural populations15.
For a global-mean warming of around 1.5°C above pre-industrial levels, more drastic
effects of climate change are to be expected. The largest sea port in East Africa, Mombasa
(Kenya) faces major risks due sea level rise and to climate extremes such as flooding, causing
major damage yearly, often accompanied by loss of lives16. In contrast, in Mediterranean
Africa, an up to 40% decrease of precipitation is expected with a 2°C increase in
temperature17. A recent study showed that by mid-century, aggregate production changes in
the Sub-Sahelian Africa will amount to -22, -17, -17, -18 and -8% for maize, sorghum, millet,
groundnut and cassava30.
11 At these temperatures, increasing risks of severe impacts on natural ecosystems and
biodiversity are expected: 10 to 15% of Sub-Saharan species will likely be at extinction
risk18. Additionally, all coral reefs will have beached and many will be widely damaged19.
Humankind is inherently dependent on their natural environment and healthy ecosystems and
rich biodiversity provide human societies with indispensable services for their development
and maintenance over time. In the long run, the impoverishment of ecosystems and loss of
biodiversity present potentially catastrophic consequences for societies. In Haiti, for example,
extreme storm events, attributed also to climate change, led to human disasters, mainly due to
very impoverished ecosystems: deforested mountainsides caused flooding of coastal plains
and rivers often overflow due to oil erosion, burying houses and people in mud20. Whilst
climate change is not the cause of deforestation, it serves to illustrate the danger of loss of
services from ecosystems such as forests.
South Asia is one of the more flood-vulnerable regions in the world. In Bangladesh,
analysis shows that most of the expected changes in flood depth and extent would occur
between 0 and 2°C above pre-industrial levels. At 1.5°C above 10% of area will probably be
lost due to a sea level rise of 45 cm21.
Figure 6 and Table S1 (Appendix) contain examples of on impacts of special relevance
for LDCs. Most of the scientific literature concerns examples impacts in different regions of
Africa, or the Indian subcontinent that includes Bangladesh, Nepal and Bhutan. Limited data
is available for Small Island Developing States.
Figure 6: Information from IPCC AR4 on impacts in Africa (see also Figure 5). Conclusions
The findings of the scientific community assessed in IPCC AR4 and published more recently
show a negative balance for LDCs at current levels of warming and overwhelmingly negative
at levels expected on the coming century. The evaluation of a global target for limiting global
warming needs to take into account this heterogeneity and the interests of countries that take
the bigger share of impacts. The periodic review mentioned in the Cancun Agreements will
assess the adequacy of the 2 and 1.5°C global goals. However, given that these goals are only
an approximate indicator for climate impacts in LDC and other regions and the vulnerability
of LDCs to the adverse impacts of climate change indicate that the review must also address
global-mean indicators other than temperature change such as concentrations and sea level
and contain sufficient information and regional detail to define “acceptable“ levels of
warming for LDCs. Comparable to the selection of climate impacts on LDCs discussed
above, the terms of reference for the review need to be established to make sure the review
will contain the required scientific information for reflecting LDCs interests, as well as their
vulnerabilities to the adverse effects of climate change.
12 Appendix
Table S1: Overview of scientific literature findings on climate-change impacts across global-warming levels, and regions and sectors. Focus on LDCs.
Impact/Vulnerability To Present 1°C to 1.5 °C about 2 °C above 2.5°C Water stress Mali is experiencing a climate zone shift with a shift of agro-­‐
ecological zones to the south, evidenced by a decrease in average rainfall of about 200 mm over the past 50 years and an average increase in temperature 22
of 0.5 °C 75 to 250 million people at risk of 18
increased water stress by 2020 350-­‐600 million people at risk of 18
increased water stress by 2050 Mediterranean Africa: Up to 40% 17
decrease of precipitation Proportion of arid and semi-­‐arid lands in Africa likely to increase by 5% to 8% (60-­‐90 million ha) by 35
2080s Reduced power generation from hydro-­‐electric plants (due to water stress) alone is estimated to provide a climate induced loss in national GDP of up to 1.7% in 23
2030 (Tanzania) Increasing risk Increasing frequency of droughts and floods in North African countries. The region experienced one drought every 10 years at the beginning of the th
20 century, to a level of five or six droughts every ten years by 14
2003 Haiti: extreme weather events (four hurricanes and tropical storms) hit the island in the space of a few weeks, having catastrophic consequences for 20
the local population Energy supply Increased drought and aridification, along with rising temperatures have led to major problems with the Akosombo dam hydroelectric power 10-­‐13
production in Ghana
Increasing risk 13 Impact/Vulnerability To Present 1°C to 1.5 °C about 2 °C above 2.5°C Ecosystems and biodiversity Observed shifts in species distribution caused by increasing 24,25
aridification in West Africa
. Increase aridification leading to adverse changes in Okavango delta region of 26-­‐28
southern Africa
Increasing risk of severe impacts on ecosystems and 18,31
biodiversity
10-­‐15% Sub-­‐Saharan species at risk of extinction (assuming no 18
migration of species) 25-­‐40% Sub-­‐Saharan species at risk of extinction (assuming no 18
migration of species) Endemic flora of southern Africa on average reduced by about 40% in habitat specific species richness. Assumptions underpinning the underlying methods might lead to over-­‐
estimates of rate and extent of 32
potential impacts (around 2°C) Projections of 5,197 studies suggest that 25%–42% of African plant species could lose all 32
suitable range by 2085 (3-­‐3.5°C) Wildlife populations have suffered from increasing 29,30
drought
Agriculture and crop production Increasing aridity in eastern and southern Africa is exacerbating 15
rural poverty and vulnerability In some countries the projected reductions in yield could be as 18
much as 50% by 2020 Up to 2,5% decrease yield of rice 33
in Bangladesh 6% to 15% loss in agriculture and 22
livestock production (Mali) 0.7% to 1.7% reduction in GDP due to losses in agriculture and 22
livestock (Mali) Climate induced increase of malnutrition is up to 120% 34
(Tanzania) (around 1.5°C) Bangladesh: flooding risk increases most rapidly between 0 21
to 2°C warming (around 1.5°C) Economic costs of losses agricultural production likely to reach between 2-­‐3% and 17-­‐18% of 2002 GDP by 2050, on low terrain (e.g., Kiribati) islands for warming of 1.5-­‐1.9°C increase by 34,35
2050
(around 1.5°C) 14 Risk of highly adverse and severe impacts on food production in 36
some African countries o
(1.5-­‐2.0 C) In South Africa crop net revenues could fall by as much as 90% by 2100, with small farmers being 18
the most affected Agricultural losses possibly severe for several areas in Africa: Sahel, 18
East Africa and southern Africa Estimated agricultural losses of GDP by 2100: 2% to 7% in parts of the Sahara, 2% to 4% in western and central Africa, and 0.4% to 1.3% in northern and 35
southern Africa Decreases in cereal production for some crops in low latitude 36
o
poor regions (1.5-­‐2.0 C) 20% decrease yield of millet in Sahel, regionally the major food 37
crop (with sorghum) (around 2°C) 30% reduction of maize 38
production in South Africa , 15% reduction of millet in Central Africa and 15% reduction in 38
Cowpea in East Africa Sub Sahelian Africa: 95% probability crop damages exceed 7%, and 5% probability that they Wheat production likely to 35
disappear from Africa by 2080 Sub Sahelian Africa: 40% 37
decrease yield of millet (around 3-­‐3.5 °C ) Bangladesh: Small further increases flooded area (most flood-­‐prone areas already 21
flooded) (around 3-­‐3.5°C). Impact/Vulnerability To Present 1°C to 1.5 °C about 2 °C above 2.5°C exceed 27% by the 2050s (around 2°C). 39
Bangladesh: 24-­‐30% increase in 21
mean flooded area (around 21
2°C) >20% reduction in length of growing period in agricultural areas in arid and semi arid (livestock only) and semi-­‐arid 40
(crop/livestock) in Africa Malnutrition Droughts and declining rainfall have had an adverse impact along with other factors in sub-­‐
41,42
Saharan Africa
The climate induced increase of malnutrition is estimated to 34
reach up to 120% (Tanzania) Increasing risk Increasing risk Rainfall Spatial extent of drought has increased over the last fifty years, with largest effects in West 43
Africa 10% decrease of the annual amount of rainfall with a 25% increase of variability and 20% decrease of annual amount of rainfall with 50% increase in variability under a “moderate” and “high” scenario for central 34
region of Tanzania, respectively Projected decrease in annual mean rainfall by 20% along the Mediterranean coast, extending into the northern Sahara and 18
along the west coast to 15 °N Decrease in austral winter (June to August) rainfall in much of southern Africa (30% decrease under the SRESA2 scenario), especially in the extreme west 18
(up to 40% decrease) Increase in annual mean rainfall in tropical and eastern Africa by 18
around 7% Malaria Observed increase in highland 44
Malaria linked to warming and is known to be climate sensitive 45-­‐48
disease
Increasing risk Previously malaria-­‐ free highland areas in Ethiopia, Kenya, Rwanda, and Burundi could experience modest incursions of malaria by 18
2050 There is strong evidence that the 15 5%-­‐7% potential increase (mainly altitudinal) of malaria distribution 18
in Africa by 2100 Areas currently with low rates of malaria transmission in central Somalia and the Angola highlands Impact/Vulnerability To Present 1°C to 1.5 °C 16 about 2 °C above 2.5°C impact on health would be greater with warming in excess of 2 C of global mean temperature before the end of this century than warming that remains below 49
this value could become highly suitable by 18
2080 Impact/Vulnerability To Present 1°C to 1.5 °C about 2 °C above 2.5°C Sea level rise Tanzania has 800 km of coast line and multiple islands where impact of sea level rise can already be seen (salination of wells, destruction of 34
infrastructure) The largest sea port in East Africa, Mombasa faces major risks. For 0.3m sea level rise around 17% of Mombasa's area could be submerged, and a “larger area rendered uninhabitable or unusable for agriculture because of water logging and salt 16
stress” . Tourism resources such as beaches, historic and cultural monuments and port infrastructure, would be 16
negatively affected Substantial losses predicted for some countries up to 14% of 51
GDP . Costs of adaptation could amount to at least 5%-­‐10% of 52
GDP In Kenya, losses for three crops (mangoes, cashew nuts and coconuts) could cost almost US$ 500 million (~2% of GDP in 2007) 18
for a 1 m sea level rise A 0.5m sea level rise combined with the projected wave and storm surge effects of a 1-­‐in-­‐50 year cyclone expected to overtop port facilities damaging wharves and flooding of the hinterland 35
(Samoa) (around 2°C) In Eritrea, a one meter sea level rise is estimated to cause damage of over US$ 250 million (~18% of GDP in 2007) as a result of the submergence of infrastructure and other economic installations in Massawa, one of the country’s 53
two port cities Egypt: Sea-­‐level rise of 0.4 m would significantly reduce food self-­‐sufficiency from 60% in 1990 50
to 10% by 2060 Loss of about 17% of area for 1 m 54
sea level rise (around 3-­‐3.5°C) Bangladesh: loss of 10% of area 21
due to sea level rise of 45 cm (around 1.5°C ) South Pacific region small islands sea level rise of 0.25-­‐0.58m projected to put much of the infrastructure at serious risk from inundation, flooding and physical damage associated with coastal land loss. Small islands of the Indian Ocean and the Caribbean are expected to face similar 35
threats (around 1.5°C) Small islands of the Indian Ocean and the Caribbean are expected 35
to face similar threats Coral reefs Coral reef bleaching event in Kenya: severe effects already Increased frequency of mass coral bleaching events due to 17 All coral reefs bleached with widespread damages to coral reef Widespread mortality of coral reefs, with reefs overgrown by Impact/Vulnerability To Present observed from 1998
1°C to 1.5 °C 55,56
19
19
thermal stress systems Risk of severe bleaching every five years in Indian Ocean o
between 10-­‐15 S latitude by 57
2010-­‐2025 Risk of loss of coral reefs in Indian o
57
Ocean between 0-­‐15 S latitude about 2 °C 18 Due to ocean acidification, corals around the world are likely to stop growing once atmospheric CO2 concentration climbs above 58,59
about 450 ppm
(1.5 to 2°C) above 2.5°C 19
algae, due to thermal stress (2.5-­‐3.5°C) Due to ocean acidification, corals around the world are likely to start dissolving above 550 ppm 58,59
CO2
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