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A status quo, vulnerability and adaptation assessment of the physical and socio-economic effects of climate change in the Western Cape, Rep
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... The climate of this zone is influenced by the movement of warm, moist air from the Indian Ocean, producing all-year rainfall (Du Plessis and Scholms 2017). This region's climatic pattern is largely due to the subcontinent's location relative to low-pressure systems (between 40° and 50°S) (Midgley et al. 2005). Seasonally, when the westerly waves shift northward, these low-pressure systems bring rainfall to the southwestern part of the country in the form of cold fronts (Louw 2007). ...
... Seasonally, when the westerly waves shift northward, these low-pressure systems bring rainfall to the southwestern part of the country in the form of cold fronts (Louw 2007). Thus, rainfall in the Western Cape is typically caused by cold fronts and associated extratropical cyclones, or by rare westerly disturbances such as cut-off lows, which frequently cause extreme rainfall events in the spring and autumn (Midgley et al. 2005). The Western Cape region is also influenced by coastal low-pressure systems, which generate hot, dry 'berg' winds that blow from the interior and cause aboveaverage warm conditions in the spring and late winter (Louw 2007). ...
Several studies have shown that climate change may enhance the severity of droughts over the Western Cape (South Africa) in the future, but there is a dearth of information on how to reduce the impacts of climate change on water yields. This study investigates the extent to which land-use changes can reduce the projected impacts of climate change on hydrological droughts in the Western Cape catchments. For the study, the Soil Water Assessment Tool (SWAT +) model was calibrated and evaluated over several river catchments, and the climate simulation dataset from the COordinated Regional Downscaling EXperiment (CORDEX) was bias-corrected. Using the bias-corrected climate data as a forcing, the SWAT + was used to project the impacts of future climate change on water yield in the catchments and to quantify the sensitivity of the projection to four feasible land-use change scenarios in the catchments. The land-use scenarios are the spread of forest (FOMI), the restoration of shrubland (SHRB), the expansion of cropland (CRDY), and the restoration of grassland (GRSL).
The model evaluation shows a good agreement between the simulated and observed monthly streamflows at four stations, and the bias correction of the CORDEX dataset improved the hydrological simulations. The climate change projection features an increase in temperature and potential evaporation, but a decrease in precipitation and all the hydrological variables. The drying occurs across the Western Cape, with the magnitude increasing with higher global warming levels (GWLs). The land-use changes alter these climate change impacts through changes in the hydrological water balance. FOMI increases streamflow and decreases runoff, while SHRB decreases streamflow and runoff. The influence of CRDY and GRSL are more complex. However, all the impacts of land-use changes are negligible compared to the impacts of climate change. Hence, land-use changes in the Western Cape may not be the most efficient strategies for mitigating the impacts of climate change on hydrological droughts over the region. The results of the study have application towards improving water security in the Western Cape river catchments.
... Here, we explore how climate change influences shifts in species ranges among mutualists in the CFR, we applied environmental niche modelling for each of 11 birdpollinated Proteaceae species, for combined occurrences of 71 birdpollinated Proteaceae and each of two important nectar-feeding bird pollinators which are endemic to this region. A previous study has predicted that the climate of the CFR, especially in the northern limit, will get drier and warmer in the future (Midgley et al., 2005); hence, we hypothesize that bird-pollinated Proteaceae and endemic nectar-feeding bird pollinators will experience range contraction in this region under future climate scenarios. We also hypothesize that the rate of range contractions will vary between Proteaceae and bird pollinators, leading to predicted changes in the degree of geographical range overlap of bird-pollinated Proteaceae and nectar-feeding birds under future climate scenarios. ...
... Bird pollinators in South Africa, especially our study species with ranges restricted to the CFR, are at the greatest risk of population decline due to climate change, as they may be unable to adapt to new suitable environment under future climate conditions (Simmons et al., 2004). The climate projection of the CFR shows the region will get warmer and drier, leading to extreme events such as drought and wildfire (Hewitson & Crane, 2006;Midgley et al., 2005). For Proteaceae, which are sensitive to temperature and precipitation change, climate change may inhibit seedling germination or increase seedling mortality and the development of resprouting Proteaceae in this region (Mustart et al., 2012), as temperature above species thermal range will induce poor development and decline in Proteaceae diversity (Louw et al., 2015). ...
Aim: Climate change influences species distribution in space and time, but predicting
the overlap in the range of interacting species under different climate scenarios
remains a challenge. Here, we explore how climate change influences shifts in species
ranges among mutualists.
Location: Cape Floristic Region (CFR), South Africa.
Taxon: Proteaceae and Passeriformes.
Methods: We used machine-learning
algorithms (random forest and boosted-regression
trees) and regression model (generalized additive models) to predict range
shifts of 11 bird-pollinated
Proteaceae species, combined occurrence prediction of
71 bird-pollinated
Proteaceae and their two most important, endemic, pollinator
bird species. We determined the degree of overlap in geographical ranges of nectar-feeding
birds and Proteaceae under different climate scenarios. Species ranges were
projected to the years 2050 and 2070 using representative concentration pathways
(RCP) 4.5 and 8.5 and three global climate models.
Results: The majority of Proteaceae species in our model are predicted to experience
range contractions, which ranged from 1% under 2050 RCP 4.5 CCSM4 to 79% under
2070 RCP 8.5 CNRM-CM5
climate scenarios, leading to 55% and 62% range loss for
Cape sugarbird and orange-breasted
sunbird, respectively, under extreme climate
scenarios. Proteaceae species are predicted to experience least overlap with nectar-feeding
birds in the northern and eastern range under future climate scenarios.
Main Conclusion: Climate change threatens species occupying the mountain range of
the northern limit and other regions of the CFR. Reduced range overlap of mutualists
may have significant implications for the reproduction and persistence of Proteaceae.
We suggest active monitoring of Proteaceae populations in regions where species are
predicted to lose their range, particularly so for threatened species with small ranges.
... [6][7][8]) have shown evidence of (a) a changing rainfall seasonality for the December -January -February period, which is also the main rainfall season for large parts of southern Africa, (b) a decrease in rainfall during September -October -November period suggesting a reduction in early season rainfall, and (c) a possible decline in the winter rainfall for the western region of South Africa. Furthermore, in the assessment of the implications of climate change for South Africa's Western Cape Province Midgley GF, et al. [9] found evidence of significant warming trends for particular seasons in the Western Cape. Kruger A [10] reported significant decreases in annual rainfall the northern parts of Limpopo, as well as significant increase0073 in annual rainfall for areas including the northern part of North-West. ...
... In other words, households from the Western Cape Province have a higher probability of paying for their solid wastes disposals than with their counterparts from other provinces. This could be due to the Western Cape Province's single largest contributor to the region's economy with agricultural produce and wine dominating exports (Midgley et al., 2005). Additionally, the coefficients of age (−0.0153) and household's frequency of waste recycling (0.2168) were significant (p < 0.01). ...
With rapid population growth and urbanization, the global annual waste generation is expected to increase to 3.40 billion tonnes by the year 2050, while improper waste disposal poses a potential threat of growing concern. Using a South African nationally representative survey dataset, the General Household Survey, this study unraveled the determinants of solid waste generation and factors influencing payment for its disposal. The estimation approach employed was essentially based on descriptive (percentage, standard deviation, mean) statistics. Additionally, Tobit regression of the composite solid waste were generated from the Principal Component Analysis, while Probit Regression model assessed the factors influencing the household’s payment for solid waste. The empirical results revealed that household’s socio-economic characteristics contributes to solid waste generation and payment for its disposal. The results of the two models indicated that, although household’s asset portfolio (financial, physical, natural, and human assets) appear intangible, they contributed significantly to solid waste generation and payment for its disposal. Therefore, policy incentives targeted at investment in human capital, environmental awareness programmes and clearer solid waste management strategies should be encouraged in South Africa, given that environmental sustainability is key to the households’ health and economic prosperity.
... Moreover, the effect of anthropogenic climate change and resulting shifts in plant flowering phaenology 35 on past and present pollen seasons cannot be discounted. Therefore, considering predicted changes in climate and seasonal rains to come (e.g., Ref. 36) continued long-term pollen monitoring with the addition of more sites will become increasingly important to predict changing allergy seasons in the future. ...
Background: Pollen monitoring has been discontinuously undertaken in South Africa, a country with high biodiversity, a seasonal rainfall gradient, and nine biomes from arid to subtropical. The South African Pollen Monitoring Network was set up in 2019 to conduct the first long-term national aerospora monitoring across multiple biomes, providing weekly reports to allergy sufferers and healthcare providers.
Methods: Daily airborne pollen concentrations were measured from August 2019 to August 2021 in seven cities across South Africa. Updated pollen calendars were created for the major pollen types (>3%), the average Annual Pollen Index over 12 months was calculated, and the results were compared to available historical data.
Results: The main pollen types were from exotic vegetation. The most abundant taxa were Poaceae, Cupressaceae, Moraceae and Buddleja. The pollen season start, peak and end varied widely according to the biome and suite of pollen taxa. The main tree season started in the last week of August, peaked in September and ended in early December. Grass seasons followed rainfall patterns: September–January and January–April for summer and winter rainfall areas, respectively. Major urban centres, for example, Johannesburg and Pretoria in the same biome with similar rainfall, showed substantive differences in pollen taxa and abundance. Some major differences in pollen spectra were detected compared with historical data. However, we are cognisant that we are describing only 2 years of data that may be skewed by short-term weather patterns.
Conclusions: Differences in pollen spectra and concentrations were noted across biomes and between geographically close urban centres. Comparison with historical data suggests pollen spectra and seasons may be changing due to anthropogenic climate change and landscaping. These data stress the importance of regional and continuous pollen monitoring for informed care of pollinosis.
... There is hardly any quantitative analysis on the impact of climate change or weather changes on South African wine production, even if Midgley et al.(2005) found significant warming trends for minimum and maximum temperatures at 12 weather stations for the period 1967-2000 and Bonnardot and Carey found (2008) a significant increase in annual temperatures for the period 1942-2006 for South African wine regions. Vink et al. (2012) suggest that climate change has an impact on the diversity of the South African wine industry and Conradie et al. (2002); Bonnardot et al. (2005); White et al. (2006); and Deloire et al. (2009Deloire et al. ( , 2010) as well suggest changing wine styles, but there is no focus on specific regions or grape varieties. ...
Our study aims to examine the effects of climate change and irrigation on grape yields in South Africa. To accomplish this, we employ artificial neural networks to construct a robust regression model. By leveraging this model, we delve into the intricate dependencies between climate parameters, various irrigation techniques, and grape yields. Through our analysis, we seek to elucidate the complex relationships that exist within this domain.
... Improved stormwater strategies may be necessary as a rise in sea level, storm surge and heavy rainfall are expected to exacerbate water pollution, compromise drinking water and damage coastal treatment plants (Kessler 2011). Climate shocks and stressors are posing physical risks to the Western Cape (including the City of Cape Town) that will pose risks to the economy as well (Midgley et al. 2005;Cartwright et al. 2012; City of Cape Town 2022). ...
Estimating the economic risks of climate shocks and climate stressors on spatially heterogeneous cities over time remains highly challenging. The purpose of this paper is to present a practical methodology to assess the economic risks of climate change in middle-income cities to inform municipal climate response strategies. Building on a capital-based framework (CBF), spatially disaggregated baseline and future scenario scores for economic wealth and its exposure to climate change are developed for six different classes of capital across 77 major suburbs in Cape Town, South Africa. Capital-at-risk was calculated by combining relative exposure and capital scores across different scenarios, with population impacted for major suburbs and the city’s eight main planning districts. The economic risk assessment presented here provides a generic approach to assist city managers through an enhanced understanding of the relative levels of capital endowment across the city vis-à-vis relative levels of exposure to climate-related hazards over time.
... The Western Cape accounts for 12% of South Africa's total agricultural area, provides 20% of the nation's total agricultural production outputs, and nurtures a world-famous wine appellation [21,22]. The climate conditions across the region are the temperate Mediterranean, with warm, dry summers and mild, moist winters, rendering it favorable for cereal farming such as wheat, oats, barley, and viticulture [23][24][25]. Average summer temperatures range from 5˚C to 27˚C, while winter temperatures range from 5˚C to 22˚C [26]. ...
The growing effect of CO2 and other greenhouse gas (GHG) emissions on the extreme climate risks in the Western Cape, South Africa, calls for the need for better climate adaptation and emissions-reduction strategies to protect the region’s long-term social-economic benefits. This paper presents a comprehensive evaluation of changes in the future extreme events associated with drought and heatwave under three different greenhouse gas (GHG) emissions scenarios: Representative Concentration Pathway (RCP) 2.6, RCP 4.5, and RCP 8.5, from moderate to severe, respectively. Various diagnostic indices were used to determine how future heatwaves and drought will respond to each different RCP climate scenario in Western Cape based on Max Planck Institute-Earth System Model/REMO (MPI-ESM/REMO). The projected simulation results revealed that drought and heatwave extreme climate indices suggest strong relationships between future extreme climate risks and GHG emissions for Western Cape, South Africa. Anthropogenic activities and growing GHG emissions will lead to severer extreme climate stress in terms of drought and the duration, frequency, and magnitude of heatwave stresses. As a result, we believe that reducing the GHG emissions to alleviate future extreme climate stress becomes a practical solution to protect the local’s socio-economic system and further maintain the region’s economic prosperity.
Introduction
There are mounting demands to undertake climate risk and vulnerability (CRV) assessments for policy, planning, funding, insurance, and compliance reasons. In Africa, given the adaptation imperative, this is particularly important. Increasingly, it has become clear that sub-national assessments are needed to inform adaptation practice. However, there has been relatively little guidance on how to undertake these more local assessments and aggregate them making it difficult for national governments to know the extent and variability of climate vulnerability and risk across the country.
Methods
In South Africa, the national government, led by the Department of Forestry, Fisheries and the Environment (DFFE), undertook to establish a common framework to guide the development and review of CRV assessments. This paper presents the framework that was co-developed through a series of engagements with stakeholders active in implementing and supporting CRV assessments.
Results
The framework is intended to provide guidance on what to consider when undertaking CRV assessments within diverse South African contexts in order to enable alignment, comparison, and aggregation between them and work towards an effective climate adaptation response across scales. Rather than standardizing a methodology, the framework promotes the use of a standard set of concepts as the basis for each assessment and profiles a diversity of methods, tools and data sources for applying the concepts in a contextually sensitive way. This provides a flexible yet structured sequence of three interlinked steps in a risk and vulnerability assessment process, namely: (1) Planning, (2) Scoping and (3) Assessing. The framework guides users through the choice and application of three assessment depths, depending on decision-context, resourcing and extent of pre-existing data and information. It encourages the integration of participatory and indicator-based methods through an impact chain approach, profiling more than 30 freely available tools and resources. This process builds a strong evidence base and a deepening set of engagements and shared understanding between relevant stakeholders, upon which to act.
Discussion
This South African process can provide insight and support for actors driving the climate agenda in other countries looking to develop comparable assessments as the basis to drive equitable and transformative climate action and learning.
Meeting the needs of multiple users and uses of freshwater resources is becoming progressively challenging. The response to the 2015–2018 Western Cape drought in South Africa offers lessons for both commercial crop growers and policymakers to enhance resilience. The drought highlights the complex interactions between water supply for urban and agricultural uses. This study employed a mixed-methods approach by combining the five capitals (natural, physical, financial, human, and social) of the sustainable livelihoods framework with semi-structured interviews to assess the impacts of the hydrologic and socio-economic drought on irrigated apple production. Data used for the study included production statistics, dam and water flow, weather data, and interviews. Results highlight a progressive weakening of the natural and physical capital between 2015 and 2018. Human capital in the form of expert consultants together with social capital of networks proved key to mitigating the impact of drought on apple production. The study also found that growers’ adaptive capacity was high as they made use of multiple capitals available to them. This resulted in lower than anticipated impacts on production and in turn stabilized financial capital available to farmers. Lessons from the drought show that building human and social capital can significantly improve the resilience of commercial farms which form part of complex water systems. Urban water-related vulnerabilities and demand are closely interlinked with the vulnerability and adaptive capacity of irrigated agriculture. Thus, policies which facilitate the in-tandem adaptation of these sectors are likely to be most successful in building resilience.
Informal or ‘spontaneous’ settlements located in the cities of the developing world have long been the subject of international donor agency debates and spending (Abrams, 1966; Davidson, 1984; Van de Laar, 1980; Marcuse, 1992), academic discourse (Bond, 1996; Huchzermeyer 1999; Hindson & McCarthy 1994; Kellet & Napier 1995), civic organisation activism (Dev. Action Group 1996) and official government angst (Turner 1976).
Advocacy groups who have directed their efforts at addressing the problems of inadequate urban housing have been involved in the ongoing attempt to get governments to priorities shelter issues. Governments used to be urged to address the problem of sub-standard housing because of the sanitary threat unserviced and overcrowded settlements posed to formal residents of cities (McGranahan, Jacobi, Songsore, Surjadi & Kjellen; 2001). Subsequently the discussion was contextualised within the demographic trends of population growth, migration and urbanisation (Abrams, 1964; Gilbert and Gugler, 1992). A recurring theme for more than thirty years has been the importance of systems of land tenure, and the need to grant appropriate forms of tenure to the urban poor (Angel, 1983). More work was done around the environmental health aspects of living in unhealthy housing and an attempt was made to alert authorities to the real costs of ill health and loss of productivity that resulted from life in informal housing (WHO, 1999; Ranson, 1991). Recently work on urban poverty alleviation has demonstrated the sensitivity or vulnerability of the livelihoods of people living in poor urban circumstances (Moser, 1998; DFID …
Aim To compare theoretical approaches towards estimating risks of plant species loss to anthropogenic climate change impacts in a biodiversity hotspot, and to develop a practical method to detect signs of climate change impacts on natural populations.
Location The Fynbos biome of South Africa, within the Cape Floristic Kingdom.
Methods Bioclimatic modelling was used to identify environmental limits for vegetation at both biome and species scale. For the biome as a whole, and for 330 species of the endemic family Proteaceae, tolerance limits were determined for five temperature and water availability-related parameters assumed critical for plant survival. Climate scenarios for 2050 generated by the general circulation models HadCM2 and CSM were interpolated for the region. Geographic Information Systems-based methods were used to map current and future modelled ranges of the biome and 330 selected species. In the biome-based approach, predictions of biome areal loss were overlayed with species richness data for the family Proteaceae to estimate extinction risk. In the species-based approach, predictions of range dislocation (no overlap between current range and future projected range) were used as an indicator of extinction risk. A method of identifying local populations imminently threatened by climate change-induced mortality is also described.
Results A loss of Fynbos biome area of between 51% and 65% is projected by 2050 (depending on the climate scenario used), and roughly 10% of the endemic Proteaceae have ranges restricted to the area lost. Species range projections suggest that a third could suffer complete range dislocation by 2050, and only 5% could retain more than two thirds of their range. Projected changes to individual species ranges could be sufficient to detect climate change impacts within ten years.
Main conclusions The biome-level approach appears to underestimate the risk of species diversity loss from climate change impacts in the Fynbos Biome because many narrow range endemics suffer range dislocation throughout the biome, and not only in areas identified as biome contractions. We suggest that targeted vulnerable species could be monitored both for early warning signs of climate change and as empirical tests of predictions.
The water resources of the Western Cape province, and the catchment areas that produce them, need to be carefully managed if future demands for water are to be met. Good catchment management, in the form of programmes to control alien invasive plants, provides an additional means for preventing losses of water, but needs to be justified financially. Previous programmes aimed at the control of alien plants have been curtailed due to a lack of funds in the recent past, as they were conducted for reasons of nature, rather than water, conservation. However, recent studies have highlighted the impacts of alien plants on water resources, and have forced planners to take these impacts into account. In this paper, we review the history of alien plant control programmes, and assess the costs (financial) and benefits (in the form of reduced losses of water from invaded catchments) that would arise from such control. We use the standard practice of discounting future costs and benefits arising from planned and existing water supply schemes to estimate the relative efficiency of the schemes. By modelling the spread and effects of alien plants on streamflow, we show that alien plant control is effective and efficient. In the case of the proposed Skuifraam scheme (the preferred next option to supply water to Cape Town), water can be delivered at a cost of 57 and 59 c kl-1, respectively, with and without the management of alien plants, for example, indicating that such management is cost-effective. Clearing invasive plants from the existing Theewaterskloof catchment would deliver additional water at only 13.6% of the cost of delivery from the new Skuifraam scheme (unit reference values of 8 and 59 c kl-1 respectively). The analyses also show that an early investment in clearing is more cost effective than a later investment, as costs increase and yields decrease the longer the catchment is left to become more invaded. Many other benefits, including avoiding serious impacts on biodiversity, catchment stability and fire management, and enhancing social upliftment, have not been included in this assessment, and add to the argument for implementation of the programme for clearing invasive alien plants.
Sources of brown haze was investigated in the Cape Town region to minimize health risks and its degrading effect on the tourist industry. Brown haze is the brown-colored smog during wintertime in the Cape Town region which comes from different soils, road dust, sea salt, coal and oil fired boilers, refinery emissions, fertilizer factory emissions, diesel combustion, petrol combustion, wood tires, grass fires, and tire burning. Sampling was conducted from July 1995 to June 1996 in a 12 hr filter loading of haze. Ambient particulate sampling took place at four sites, namely, Wynberg, Goodwood, Table View, and Central Business District, which fall into four of the six meteorological zones that were identified in the Cape Town Metropolitan Area. Using the Chemical Mass Balance Model, diesel vehicles were the largest single source of PM2.5, and emission inventory was used to apportioned sulfates and nitrates, indicating that heavy fuel oil was the largest single source of SO2, petrol was the largest single source of NOx and volatile organics, and diesel vehicles were the largest single source of PM2.5. PM2.5 emissions were the most important cause of brown haze.
Seeds of 13 Aspalathus species and three other Fabaceae species from the fynbos vegetation of the Western Cape Province, South Africa were exposed to pre-germination treatments comprised of combinations of four different temperatures (60°C, 80°C, 100°C, 120°C) and three time durations (5, 15 or 30 minutes). The 'heat-sum' (product of temperature and time) most effective in stimulating germination in a particular species was shown to be negatively correlated with a specific seed characteristic, namely the proportion of whole seed to embryo plus cotyledon mass. It may thus be possible to predict the temperature-time combination most effective for stimulating germination in Aspalathus species and possibly other members of the Febaceae by using this ratio. However, predicting the number of seeds likely to germinate in the field after fires of different intensity requires further information concerning the distribution of seeds in the soil which is currently unknown for fynbos legumes.