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COP17 - SAEON’s contribution toward understanding climate change impacts
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COP17. More talk and political posturing, or some clear-headed decision-making amongst the countries of this globe about the looming threat of climate change?
Well, what could make a difference is vastly improved information about the effects of climate change on the world’s marine, terrestrial and aquatic systems. With COP 17 taking place in our own country, it behoves us to take a closer look at SAEON’s efforts to date in providing such information for South Africa.
This article summarises what fewer than a dozen scientists have established in five or less years for meeting this need in conjunction with SAEON’s partners. Notwithstanding severe resource constraints, we have attempted to pursue both breadth and depth through efficient streamlining and dovetailing of individual efforts across the six SAEON nodes and with partners.
Monitoring our oceans
Our climate is driven by the oceans. SAEON is addressing potential climate-change impacts from the level of the southern hemisphere through to local marine or coastal areas in order to understand the links between climate change, ocean dynamics, and consequent effects on climate as well as the marine and coastal environment.
The Egagasini (marine) Node has been involved in research programmes and oceanographic modelling of the Southwest Indian ocean and the influence of the Agulhas current system flowing along our east coast in regulating our climate. A special emphasis is to distinguish climate change effects from natural variability.
Shifts in the wind field in the Southern Hemisphere have led to an increase in transport of the Agulhas current which has subsequently warmed. This could result in an increase of coastal upwelling and local cooling, the influx of warmer, saltier water into the coastal zone, coastal currents, storminess, storm surges and sea level rise.
The Elwandle (coastal) and Egagasini nodes have developed a site for intensive observation known as the Algoa Sentinel Site. Detailed monitoring (including sea temperatures, sea levels, salinity, currents, waves) of South Africa’s south and east coastal and shelf ocean, inshore of the Agulhas current, should reveal if the expectation of increased upwelling and local cooling is occurring.
Complementary monitoring is being conducted on the impact of expected changes on the marine and coastal environment. Already temperature effects on the distribution and community composition of estuarine fishes have become apparent that is expected to continue as subtropical species advance and temperate species retreat southwards.
Marine Protected Areas are proving an essential tool for monitoring of climate change impact on sub-tidal temperate marine reef biota, especially fishes, because other human impacts are ostensibly lessened. Special attention is being paid to food web structure that should reveal some of the complexity of responses.
Impact of sea-level rise (already greater than 2 mm per annum) on sediment accretion within salt marshes is being undertaken in the Knysna, Kromme, and Swartkops estuaries in order to assess whether these marshes will persist, or will drown.
Marine and coastal observation is not restricted to the east and south coast. The Benguela current flowing up the west coast and adjacent coastline traditionally served as the ‘fish-‘ and ‘lobster-baskets’ of the country. Upheaval of these systems has been well documented. SAEON is paying specific attention to the demersal fish community and lobsters. We are further contributing to analysis of historical and long-term monitoring data of fish and lobster stocks from government departments.
SAEON is also a participant of a project examining the phenomenon of coral bleaching, recognised globally as an indicator of climate change, in Maputaland.
Freshwater - the most important natural resource in this country
The diversity of the country’s terrestrial and aquatic environments provides a considerable planning challenge for SAEON. Freshwater is, however, arguably the most important natural resource in this country. Available modelling predictions of regional-scale effects on rainfall beg for long-term data of rainfall trends and consequent effects on water delivery.
The Fynbos Node has taken a lead position by assuming responsibility for maintaining monitoring of the experimental catchments in the Jonkershoek mountains above Stellenbosch – one of the four longest-running catchment experiments in the world. Rigorous statistical analysis has been undertaken of the 60 years of baseline data in order to identify trends to date in rainfall and stream flow.
The newly established (less than one year old) Grassland, Forest, and Wetlands (GFW) Node is following suit by resurrecting the sister set of catchment experiments at Cathedral Peak in the Drakensberg. A similar analysis of rainfall trends is being undertaken for the national parks across the country.
Will our valuable fynbos starve to death?
What are the consequences for changes in water availability on the vegetation cover regulating the delivery of this valuable resource? The astounding richness of fynbos vegetation may obscure the effects of climate change, but a combination of continued monitoring of long-term vegetation plots and process-based research on the response of plants to water deficits offer a first few steps toward improving projections of impact on the Cape Flora.
“Will fynbos plants starve to death or die from dehydration if there are longer dry periods?” is a fundamental research question being addressed by the Fynbos Node.
Monitoring change in the biota of our biomes
An initial focus of all terrestrial nodes is to examine whether there is any evidence for expected changes in the distribution and abundance of the biota of each biome. Climate-induced changes should be easily detected in mountain environments on account of their well defined climatic gradients and associated vegetation gradients over altitudinal gradients.
Accordingly, SAEON’s Ndlovu (savanna) Node has established a set of mountain observatories across the Limpopo and Mpumalanga provinces at which weather stations have been established and change in the distribution of certain plant, insect, and vertebrate species is being monitored. The GFW Node is set to follow suit in the Drakensberg.
Detecting impending changes
Most of our country is, however, characterised by more subdued relief. Can we detect impending changes in the distribution of major vegetation assemblages including biomes?
To this end, the Ndlovu Node is assessing potential range expansion of the mopane tree by mapping its current boundary in parts of the Lowveld.
The GFW Node is assisting study of expansion of savanna woody elements into the grassland biome, a key anticipated biome change, through follow-up of historical photography.
At a number of monitoring sites distributed across lowveld savanna, tree demography and phenology are being measured across current climatic gradients. The rivers traversing the lowveld are the lifeblood of the area. Determination of fish distributions in relation to water temperature, and the impact of infrequent flood or drought events on the aquatic environment of the Olifants River are selected observation tasks.
Elsewhere, the recently fledged Arid Node in Kimberley is collaborating with the National Department of Agriculture in maintaining monitoring of long-term grazing trials at Middelburg (the longest running in the world) that, apart from their obvious agricultural focus, offer a long-term record of putative climate-related impacts on Karoo vegetation. Incipient biome shifts may already be evident. Long-term veld monitoring in the Kalahari is to be used in much the same manner.
Involving citizens in our science
Citizen-science projects offer one of the most efficient means of engaging a large number of people in observing change. Importantly, they promote awareness and work best when concerned with objects of widespread interest or with easily implemented ideas. An obvious starting point has therefore been the bird-watching community. Monitoring includes the date of arrival of migratory birds in the lowveld and distributional changes of garden birds in the Pietermaritzburg area.
The Ndlovu (savanna) Node is promoting the planting of gardens of selected plant species at 50 schools in Mpumalanga and Limpopo Provinces so their phenology, a known sensitive indicator of climate change, can be followed. A similar approach is being prepared for other biomes.
SAEON is currently operating “uit die diepte van ons see, oor ons ewige gebergtes, en oor ons ver verlate vlaktes”1. Its efforts will, it believes, ultimately assist in improving the lives of those on this blessed continent.
1 From South Africa’s national anthem, freely translated as “from the depth of our oceans, across our ever-lasting mountains, and across our distant, desolate plains”.
