Biodiversity as a Resource for Adapting to Climate Change
by Andrew Muir
South Africa has a wealth of natural resources that are key to our development as a nation. Our natural resources include our minerals, our soil, our water and our biodiversity – for example, fish stocks, medicinal plants and game. Natural resources are a form of capital, like infrastructure, land, labour or finance – we can call them “natural capital”.
As a nation, we need to invest in maintaining, restoring and building our natural capital, so that it can help support socio-economic development for all our people. Investing in looking after our biodiversity is a way of ensuring that it works for us, to fulfil our goals of:
- Creating work and sustainable livelihoods
- Achieving rural development, food security and land reform
- Delivering water for the nation’s needs
- Providing protection against climate change
South Africa is one of the most biodiverse countries in the world: with a land area of 1,2 million km2 – representing just 1.24% of the Earth’s surface – South Africa contains almost 10% of the world’s known bird, fish and plant species, and over 6% of mammal and reptile species.
Under a “business as usual” scenario, global temperatures are predicted to increase by 4-6.4°C by 2099, and sea level to rise by 0.59m (IPCC, 2007). Impacts on Southern Africa are likely to be significant. Over the next 50 years scientists predict that the interior of our country will become warmer, and the western part of the country will become drier, with more intense and frequent fires. Rainfall patterns are expected to become less regular countrywide – with more sudden downpours and more flooding. Increased storm surges at sea may cause coastal erosion.
Mitigation measures are interventions to reduce the sources of or enhance sinks for greenhouse gases. The South African government has committed itself to reducing our emissions by significantly more than the minimum required of developing countries by the Kyoto Protocol. Adaptation measures involve adjustments to human and natural systems in response to anticipated change. Creating landscape-level corridors of biodiversity helps a region become more resilient to climate change, e.g. by retaining water in catchments and creating corridors for species to move through.
Although scientists’ predictions vary, sea level could rise by up to a metre by the end of this century, with serious implications for low-lying areas along the coast of Cape Town, Durban, Port Elizabeth and East London. Risk assessment studies are currently underway to see which parts of coastal cities may become inundated with seawater.
A study for Cape Town also predicts an 85 percent chance of extreme winds causing a 4.5 metre rise in the level of storm surges in the next five years, which could cause about R20 billion of damage to infrastructure. Storm surges along the KwaZulu-Natal North Coast in 2007 damaged roads and made a dent in tourism earnings. The Integrated Coastal Management Act will play an important role in establishing and managing set-back lines for future coastal development.
Maintaining natural habitat along the coastline can protect human settlements against storm surges and coastal flooding. In South Africa, however, many of the natural buffers provided by functioning ecosystems have already been removed or damaged. This has occurred through land reclamation, removal of coastal dunes, removal of mangroves on the east coast, stabilisation of sand that historically replenished beaches, development of estuaries and mining of sand – all of which have made the coast more vulnerable to damage from increasingly variable and rising seas
In some cases, engineering approaches to adaptation may be
appropriate, such as sea walls, groynes, dolosse and gabions. More cost-effective, however, and less vulnerable to damage themselves, are “natural solutions” that maintain biodiversity and ecosystem functioning along the coast. Examples of this approach could be maintaining sand dunes along the coast that allow beaches to shift and reform, protecting coastal mangrove swamps that buffer storms, rehabilitating estuaries and wetlands to maintain the balance between seawater and freshwater resources, and conserving kelp beds that buffer tidal swells offshore. Sometimes a combination of natural and engineered methods may be best, for example, the Milnerton golf course in Cape Town might be saved by creating vegetation buffers along the coastal dunes.
The Overberg and Garden Route in the Southern Cape have seen a number of large flood events in the past few years, some due to inappropriate development of coastal resorts and holiday homes in low-lying coastal areas allowed by municipalities. In other cases of flooding, informal settlements were inappropriately located in river floodplains because residents had no other options.
Maintaining indigenous vegetation along rivers can prevent the banks from being eroded when rivers swell during heavy rainfall. Erosion is bad because it means valuable soil resources are lost to agriculture, and also because it puts a large amount of sediment into rivers, which pollutes drinking water supplies further downstream and silts up river mouths where fish breed. Conservation agencies recommend that farmers keep a band of 20-30 metres of indigenous vegetation on either side of the river to enable this ecosystem service to be maintained.
Keeping wetland ecosystems in a healthy state is also critical to preventing floods. About 115 000 wetlands covering 4.21 million hectares, or 3.5 % of our country’s surface area, have been mapped in South Africa. These wetlands are part of our natural infrastructure for gathering, managing and delivering water – improving water quality, controlling erosion, sustaining river flows and reducing the impact of floods.
Wetlands act like giant sponges, absorbing large amounts of water during wet periods and floods, and releasing water slowly during drier periods. The destruction of more than 50% of our original wetlands has left us vulnerable to floods in many areas, a situation made worse by climate change. The Working for Wetlands programmes is investing in protecting and restoring wetlands as a critical part of adaptation to climate change, as well as creating work opportunities for unemployed people in rural areas.