Impacts, Vulnerability and Adaptation in Key South African Sectors

An input into the Long Term Mitigation Scenarios process

Prepared for: Department of Environment Affairs and Tourism

South Africa

Authors:

G Midgley, R Chapman, P Mukheibir, M Tadross, B Hewitson, S Wand, R Schulze, T Lumsden, M Horan, M Warburton, B Kgope, B Mantlana,

A Knowles, A Abayomi, G Ziervogel, R Cullis and A Theron

LTMS input Report 5 (Summary report)

October 2007

ENERGY RESEARCH CENTRE

University of Cape Town

Assessing impacts, vulnerability and adaptation in key South African sectors

i

Ten free-standing chapters make up this report, and this Executive Summary and supporting Synthesis Report serve to draw together the main findings in both an abbreviated and an extended and illustrated format that focuses on main findings, but also adds a level of detail for the purpose of communicating the key results, and the uncertainties associated with them, for the benefit of a policy maker. The chapters that make up this report are compiled as separate documents as follows. These are generally reviews of the literature available, but in some cases comprise new work that has been carried out to provide information in an area that is lacking an assessment.

1 Summary (incorporating Executive Summary and Synthesis

Report)

22 pages

2 Introduction 4 pages

3 Adaptation concepts 9 pages

4 Retrospective analysis of climate change 19 pages

5 Climate science and new scenarios 16 pages

6 Water and Hydrology 77 pages

7 Agriculture

A) Winter rainfall

B) Summer rainfall

57 pages

45 pages

8 Forestry, Environment, Biodiversity and Ecosystem services 36 pages

9 Human Health 15 pages

10 Rural Livelihoods 14 pages

11 The Urban Environment 25 pages

The following citation should be used for this report:

Midgley GF, Chapman RA, Mukheibir P, Tadross M, Hewitson B, Wand S,

Schulze RE, Lumsden T, Horan M, Warburton M, Kgope B, Mantlana B,

Knowles A, Abayomi A, Ziervogel G, Cullis R and Theron A. (2007)

Impacts, vulnerability and adaptation in key South African sectors: An input

into the Long Term Mitigation Scenarios process, LTMS Input Report 5,

Energy Research Centre, Cape Town

The suite of reports that make up the Long Term Mitigation Scenario study include the

following:

A Long Term Mitigation Scenarios for South Africa

B Technical Summary

C Technical Report

C.1 Technical Appendix

D Process Report

The study was supported by the following inputs:

LTMS Input Report 1: Energy emissions

LTMS Input Report 2: Non-energy emissions: Agriculture, Forestry and Waste

LTMS Input Report 3: Non-energy emissions: Industrial Processes

LTMS Input Report 4: Economy-wide modeling

LTMS Input Report 5: Impacts, vulnerability and adaptation in key South African sectors

Assessing impacts, vulnerability and adaptation in key South African sectors

ii

PrefacePrefacePrefacePreface

Risk and uncertainty statement

Much of the impacts assessment work reviewed in this report does not deviate far from the

recently published IPCC estimate that the most likely range for global temperature response to

CO2 doubling is from 2 to 4.5ºC, with the median response (the “climate sensitivity”) not far

below 3ºC. The approach of making assessments guided by the median climate sensitivity, as we

have done here, may appear to be logical and justifiable, but it is important to point out that this

approach significantly underestimates the risks of larger impacts due to the uncertainty inherent

in the climate sensitivity. We have found that, in general, the apparently less likely scenarios of

climate change are poorly explored in the impacts literature, and thus that this high risk region

remains largely unquantified.

The IPCC fourth Assessment Report provides the most recent and comprehensive estimate of the

likelihood that human activities are causing currently observed temperature and climate change.

Their essential conclusions are that:

“Warming of the climate system is unequivocal, as is now evident from observations of increases

in global average air and ocean temperatures, widespread melting of snow and ice, and rising

global mean sea level”

and that

“Most of the observed increase in globally averaged temperatures since the mid-20th century is

very likely due to the observed increase in anthropogenic greenhouse gas concentrations”.

This level of certainty translates to a >90% probability (9/10 chance) that human activities are

responsible for the global warming observed since the 1950’s.

This finding itself provides some level of support for a policy response, but the urgency of the

response needed is better judged on what the projected warming is likely to be, given a range of

societal choices regarding fossil fuel use, land cover change and then a range of other less critical

decisions. It is these projections that depend on the estimate of climate sensitivity. A truly risk-

averse strategy should consider fully the impacts of higher climate sensitivities, especially

because certain key feedbacks to climate from the biosphere are not yet incorporated in climate

models. But we find that these are lacking in the literature, thus providing us with published

material that yields what may be conservative estimates of impacts.

Assessing impacts, vulnerability and adaptation in key South African sectors

iii

Contents

1.1 EXECUTIVE SUMMARY 1

1.2 SYNTHESIS REPORT 6 1.2.1 Observed climate trends during modern human history 6 1.2.2 Climate science and new scenarios 7 1.2.3 Adaptation to climate change 10 1.2.4 Impact on water resources and hydrology 11 1.2.5 Impact on agriculture 12 1.2.6 Impact on forestry 14 1.2.7 Impact on terrestrial ecosystems and biodiversity 15 1.2.8 Impact on health 16 1.2.9 Impact on rural livelihoods 17 1.2.10 Impact on the urban environment 18 1.2.11 Indicative costs of climate change impacts 18

Assessing impacts, vulnerability and adaptation in key South African sectors

1

1.1.1.1. SummarySummarySummarySummary

1.11.11.11.1 EXECUTIVE EXECUTIVE EXECUTIVE EXECUTIVE SUMMARYSUMMARYSUMMARYSUMMARY

The IPCC Fourth Assessment Report (AR4) concluded in 2007 that there is a greater than 90% chance that human

activities such as fossil fuel burning and deforestation are changing the earth’s climate system. The evidence for

climate change is clear and unambiguous. Changes in climate have already been observed that are generally

consistent with model projections, and are likely to continue to occur for many decades to come even if mitigation

efforts are successful, because of lags and inertia in the global biosphere response. The global projections for a range

of assumptions of climate sensitivity and societal development scenarios are for between a 1.2º and 5.8ºC rise in

global temperature by 2100. The range of climate change projected clearly remains broad even at the global level, and

the potential impacts remain uncertain to a greater or lesser degree depending on the affected sector in question.

However, it is possible to assess sensitivities, vulnerabilities and risk associated with climate change at the national

and sub-national levels. It is also possible to explore potential adaptation options and estimate their possible costs in

relation to the costs of inaction.

Modelling studies project a range of possible scenarios and impacts in South Africa, given the uncertainties in global

greenhouse gas emissions scenarios and in the response of the climate system. Some of these projected impacts are

alarming and of immediate societal relevance – for example, a projected change in available water supply in South

Africa would have major implications in most sectors of the economy, but especially for urban and agricultural

demands. The set of studies presented here reviews currently available information on observed climate trends,

projected changes and the vulnerability to climate change across an array of key sectors that are known to show

sensitivity to climatic drivers. Where possible, adaptation responses have also been reviewed per sector, and the costs

of adaptation and damage costs due to a lack of action have been extracted – although examples of this level of work

are currently very few. The projected impacts of anthropogenic climate change in South Africa provide an important

motivation for the Long Term Mitigation Scenario project (LTMS). The main findings are summarised as follows:

▪ Climate observations and trends: Analysis of climates during the last 10 000 years, at least, indicate that the current levels of temperature in this region have seldom, if ever, been significantly exceeded. Extended dry spells in

various regions of South Africa, on the other hand, have induced severe drought conditions in living memory and

recorded history that have had major disr