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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          

   

     

 

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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  

 

     

 

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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.

     

 

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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 decision-making 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.  

     

 

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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 pre-industrial 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.

     

 

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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

     

 

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     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 decades3-5. 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 long-term 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

!"!#$%&'()(*&+,-#)./.)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.

     

 

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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 non-mitigated 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.

     

 

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Figure   4   Global   sea   level   rise   responds   to   temperature   changes   (Figure   1)   with   a   delay   of   decades   to  multiple  centuries.  For  explanation  of  line  coloring,  see  Figure  1.  Source:  Climate  Analytics  and  PIK7.  

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.  

     

 

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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  

(%  relative  to  1990)  

Annex-­‐I  emissions  

(%  relative  to  1990)  

non-­‐Annex  I  emissions  

(%  relative  to  1990)  

Non-­‐Annex-­‐I  emissions  per  capita  relative  to  Annex  I  emissions  per  capita  

(rough  estimate  using  UN  (2010)  population  projections)  

-­‐50%*   -­‐80%   -­‐20%   Non-­‐Annex  I  per  cap    ½  ×    Annex  I  per  cap  -­‐50%*   -­‐90%   -­‐5%   equal  -­‐50%*   -­‐95%   0%   Non-­‐Annex  I  per  cap    2½  ×    Annex  I  per  cap    -­‐85%**   -­‐95%   -­‐70%   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    

     

 

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 Figure  5  Selected  regional  impacts  associated  with  various  reductions  in  global  greenhouse-­‐gas  emissions.    Source:  Parry  et  al8.    

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.

     

 

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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.  

     

 

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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  of  0.5  °C22  

Increasing  frequency  of  droughts  and  floods  in  North  African  

countries.  The  region  experienced  one  drought  every  10  years  at  the  beginning  of  the  20th  century,  to  a  level  of  five  or  six  droughts  every  ten  years  by  

200314  

Haiti:  extreme  weather  events  (four  hurricanes  and  tropical  

storms)  hit  the  island  in  the  space  of  a  few  weeks,  having  

catastrophic  consequences  for  the  local  population20  

75  to  250  million  people  at  risk  of  increased  water  stress  by  202018  

 

350-­‐600  million  people  at  risk  of  increased  water  stress  by  205018  

Mediterranean  Africa:  Up  to  40%  decrease  of  precipitation17  

Proportion  of  arid  and  semi-­‐arid  lands  in  Africa  likely  to  increase  by  5%  to  8%  (60-­‐90  million  ha)  by  

2080s35  

Energy  supply   Increased  drought  and  aridification,  along  with  rising  temperatures  have  led  to  major  problems  with  the  Akosombo  dam  hydroelectric  power  production  in  Ghana10-­‐13  

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  

2030  (Tanzania)23  

 

Increasing  risk   Increasing  risk  

     

 

14  

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  aridification  in  West  Africa24,25.    Increase  aridification  leading  to  adverse  changes  in  Okavango  

delta  region  of  southern  Africa26-­‐28  

Wildlife  populations  have  suffered  from  increasing  

drought29,30  

Increasing  risk  of  severe  impacts  on  ecosystems  and  biodiversity18,31  

10-­‐15%  Sub-­‐Saharan  species  at  risk  of  extinction  (assuming  no  

migration  of  species)18  

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  potential  impacts32  (around  2°C)  

 

25-­‐40%  Sub-­‐Saharan  species  at  risk  of  extinction  (assuming  no  

migration  of  species)18  

Projections  of  5,197  studies  suggest  that  25%–42%  of  African  

plant  species  could  lose  all  suitable  range  by  208532  (3-­‐3.5°C)    

Agriculture  and  crop  production   Increasing  aridity  in  eastern  and  southern  Africa  is  exacerbating  rural  poverty  and  vulnerability15  

Up  to  2,5%  decrease  yield  of  rice  in  Bangladesh33  

In  some  countries  the  projected  reductions  in  yield  could  be  as  

much  as  50%  by  202018  

6%  to  15%  loss  in  agriculture  and  livestock  production  (Mali)22  

0.7%  to  1.7%  reduction  in  GDP  due  to  losses  in  agriculture  and  

livestock  (Mali)22  

Climate  induced  increase  of  malnutrition  is  up  to  120%  (Tanzania)34  (around  1.5°C)  

Bangladesh:  flooding  risk  increases  most  rapidly  between  0  to  2°C  warming21  (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  

205034,35  (around  1.5°C)  

Risk  of  highly  adverse  and  severe  impacts  on  food  production  in  

some  African  countries36  (1.5-­‐2.0oC)  

Agricultural  losses  possibly  severe  for  several  areas  in  Africa:  Sahel,  East  Africa  and  southern  Africa18  

Decreases  in  cereal  production  for  some  crops  in  low  latitude  poor  regions36  (1.5-­‐2.0oC)  

20%  decrease  yield  of  millet  in  Sahel,  regionally  the  major  food  

crop  (with  sorghum)37  (around  2°C)  

30%  reduction  of  maize  production  in  South  Africa38,  15%  reduction  of  millet  in  Central  Africa  and  15%  reduction  in  Cowpea  in  East  Africa38  

Sub  Sahelian  Africa:  95%  probability  crop  damages  exceed  7%,  and  5%  probability  that  they  

In  South  Africa  crop  net  revenues  could  fall  by  as  much  as  90%  by  2100,  with  small  farmers  being  

the  most  affected18  

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  

southern  Africa35  

Wheat  production  likely  to  disappear  from  Africa  by  208035  

Sub  Sahelian  Africa:  40%  decrease  yield  of  millet37  

(around  3-­‐3.5  °C  )  

Bangladesh:  Small  further  increases  flooded  area  (most  flood-­‐prone  areas  already  flooded)21  (around  3-­‐3.5°C).  

 

     

 

15  

Impact/Vulnerability   To  Present   1°C  to  1.5  °C   about  2  °C   above  2.5°C  

  exceed  27%  by  the  2050s39  (around  2°C).  

Bangladesh:  24-­‐30%  increase  in  mean  flooded  area21  (around  

2°C)21  

>20%  reduction  in  length  of  growing  period  in  agricultural  areas  in  arid  and  semi  arid  

(livestock  only)  and  semi-­‐arid  (crop/livestock)  in  Africa40  

Malnutrition   Droughts  and  declining  rainfall  have  had  an  adverse  impact  

along  with  other  factors  in  sub-­‐Saharan  Africa41,42  

The  climate  induced  increase  of  malnutrition  is  estimated  to  reach  up  to  120%  (Tanzania)34  

Increasing  risk   Increasing  risk  

Rainfall   Spatial  extent  of  drought  has  increased  over  the  last  fifty  years,  

with  largest  effects  in  West  Africa43  

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  

region  of  Tanzania,  respectively34  

  Projected  decrease  in  annual  mean  rainfall  by  20%  along  the  Mediterranean  coast,  extending  into  the  northern  Sahara  and  along  the  west  coast  to  15  °N18  

Decrease  in  austral  winter  (June  to  August)  rainfall  in  much  of  southern  Africa  (30%  decrease  under  the  SRESA2  scenario),  especially  in  the  extreme  west  

(up  to  40%  decrease)18  

Increase  in  annual  mean  rainfall  in  tropical  and  eastern  Africa  by  

around  7%18  

Malaria   Observed  increase  in  highland  Malaria  linked  to  warming44  and  is  known  to  be  climate  sensitive  

disease45-­‐48    

 Increasing  risk   Previously  malaria-­‐  free  highland  areas  in  Ethiopia,  Kenya,  Rwanda,  and  Burundi  could  experience  modest  incursions  of  malaria  by  

205018    

There  is  strong  evidence  that  the  

5%-­‐7%  potential  increase  (mainly  altitudinal)  of  malaria  distribution  

in  Africa  by  210018  

Areas  currently  with  low  rates  of  malaria  transmission  in  central  

Somalia  and  the  Angola  highlands  

     

 

16  

Impact/Vulnerability   To  Present   1°C  to  1.5  °C   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  this  value49  

could  become  highly  suitable  by  208018  

     

 

17  

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  infrastructure)34  

 

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  

stress”16.  Tourism  resources  such  as  beaches,  historic  and  cultural  

monuments  and  port  infrastructure,  would  be  negatively  affected16  

Egypt:  Sea-­‐level  rise  of  0.4  m  would  significantly  reduce  food  self-­‐sufficiency    from  60%  in  1990  

to  10%  by  206050  

Bangladesh:  loss  of  10%  of  area  due  to  sea  level  rise  of  45  cm21  

(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  threats35  (around  1.5°C)  

 

Small  islands  of  the  Indian  Ocean  and  the  Caribbean  are  expected  

to  face  similar  threats35  

Substantial  losses  predicted  for  some  countries  up  to  14%  of  

GDP51.  Costs  of  adaptation  could  amount  to  at  least  5%-­‐10%  of  

GDP52  

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  

(Samoa)35  (around  2°C)  

In  Kenya,  losses  for  three  crops  (mangoes,  cashew  nuts  and  

coconuts)  could  cost  almost  US$  500  million  (~2%  of  GDP  in  2007)  

for  a  1  m  sea  level  rise18  

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  

two  port  cities53  

Loss  of  about  17%  of  area  for  1  m  sea  level  rise54  (around  3-­‐3.5°C)    

Coral  reefs   Coral  reef  bleaching  event  in  Kenya:  severe  effects  already  

Increased  frequency  of  mass  coral  bleaching  events  due  to  

All  coral  reefs  bleached  with  widespread  damages  to  coral  reef  

Widespread  mortality  of  coral  reefs,  with  reefs  overgrown  by  

     

 

18  

Impact/Vulnerability   To  Present   1°C  to  1.5  °C   about  2  °C   above  2.5°C  

observed  from  199855,56  

 

thermal  stress19  

Risk  of  severe  bleaching  every  five  years  in  Indian  Ocean  

between  10-­‐15oS  latitude  by  2010-­‐202557  

 

systems19  

Risk  of  loss  of  coral  reefs  in  Indian  Ocean  between  0-­‐15oS  latitude57  

Due  to  ocean  acidification,  corals  around  the  world  are  likely  to  stop  growing  once  atmospheric  CO2  concentration  climbs  above  about  450  ppm58,59  (1.5  to  2°C)  

algae,  due  to  thermal  stress19  (2.5-­‐3.5°C)  

Due  to  ocean  acidification,  corals  around  the  world  are  likely  to  start  dissolving  above  550  ppm  

CO258,59  (2.5-­‐3.5°C).  The  global  

CO2  concentration  is  projected  to  reach  these  levels  in  the  period  of  

2050-­‐2080  

     

 

19  

 

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20  

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