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Section 5
Likely climate change impacts on protected areas KEY MESSAGES Studies suggest that under moderate change scenarios protected area systems will be reasonably robust in terms of sustaining biodiversity, if they are designed to take future climate change into account, include resilience building principles, and are fully ecologically representative and well managed. This is not always the case at present. Impacts will come from habitat loss, loss of suitable conditions for individual species, poor connectivity, pressures from invasive species, alteration of fire and other disturbance regimes and extreme weather events, and associated human pressures, especially those resulting from the impacts of climate change on human settlements and resource use. The challenge Modelling exercises, backed by field observations, provide the basis for assessment of climate change impact on ecosystems. Changes are expected everywhere, but the areas projected to be most vulnerable include the Amazon region, threatened by drought, forest dieback and wildfire; parts of the boreal forest; and the Arctic tundra, at risk from forest invasion528. In some areas, climate change is likely to have a transformational impact on ecosystems, leading to extreme risk of species extinction, and major changes in ecosystem functions and ecological processes. Researchers at The Nature Conservancy studied potential climate-related vegetation shifts at an ecoregional level and found potential vegetation changes on 34 per cent of global non-ice areas from 1990-2100, varying from an average of 24 per cent in Africa to 46 per cent in Europe529. Climate models undertaken in South Africa have indicated that large areas in the south and western parts of the country, within the Succulent and Nama Karoo, and parts of the fynbos biome will be transformed to more arid, desert like conditions – an ecosystem not presently found within the boundaries of the country. A loss of the fynbos biome of between 51 and 65 per cent is expected by 2050, based on the bioclimatic model and scenario used 10 per cent of endemic Proteaceae have restricted ranges within areas of the biome that are likely to be lost. It might be expected that protected areas, which have fixed locations and are often isolated, will be particularly vulnerable. In fact modelling and field observations show mixed responses. Many individual protected areas are likely to lose habitats and species, but there is evidence that well designed protected area systems may be able to withstand climate change reasonably well. One study modelled shifts in distribution of all sub-Saharan African breeding birds. It predicted that species turnover (local extinction and replacement by other species) across Africa’s Important Bird Area (IBA) network will involve over half the priority species at 42 per cent of IBAs by 2085; but in the whole network 88–92 per cent of priority species would find suitable
habitat in one or more of the IBA(s) where they are currently found. Only seven or eight species were predicted to lose all suitable habitats530. Similarly, research on 1,200 plant European species, using an “ideal” rather than the actual reserve network, found theoretical losses of 6-11 per cent of the bioclimatic range of species within Europe by 2050531. These studies look at climate impacts alone and assume that species are otherwise secure, in well managed, ecologically representative protected area networks. Another study applied distribution modelling in three regions: Mexico, the Cape Floristic Region of South Africa and Western Europe. Assuming a completed protected area network, the study found that in the Cape 78 per cent of species met the representation target for future range, in Mexico 89 per cent retained full representation, and in Europe 94 per cent. However, if the current protected area system was assessed, survival of many more species was jeopardised532. In fact, few protected area systems are ‘complete’ – a global analysis estimated that 6-11 per cent of mammals and 16-17 per cent of amphibians were “gap species” with inadequate protection, with the percentage larger for threatened species533. So as things stand, climate change may have even greater impacts for protected areas than elsewhere as systems are not fully representative and there is a northerly bias in protection where more extreme climate change is predicted534. For example one study estimated that between 37-48 per cent of Canada’s protected areas could experience a change in terrestrial biome type due to climate change535. These findings are important indicators of future trends under changing climate. What is less well understood is the relationship between ecosystem resilience and the maintenance of ecosystem services upon which so much of climate mitigation and adaptation action depends. For now, we are making the assumption that an important component of maintaining ecosystem resilience is the maintenance of the underlying composition, structure and function of natural ecosystems.