Validating the impacts of climate change through long-term observations

By Johan Pauw, Jasper Slingsby and William Bond, SAEON Tweet

A study by SAEON’s Dr Jasper Slingsby and his collaborators showed that increasingly prolonged periods of severe hot and dry weather during the first summer after wild fires is inhibiting vegetation recovery and causing loss of plant diversity in the Fynbos. “The fact that the late Hugh Taylor’s work has lately found new meaning is again a signal to decision makers that the termination of well-run environmental monitoring programmes should not be considered lightly.” – Johan Pauw, SAEON MD

We have come to expect large-scale environmental impacts in response to persistent climatic change.

The nature of these impacts is predicted by models based on theories of interactions between atmospheric systems, the biosphere, and changing socio-economic systems.

Given the massive scale of factors involved, the complexity of interactions and the inherent variability of the systems, it must be acknowledged that climate change models can hardly be expected to accurately predict climate change impacts, especially at finer scales. It is thus necessary that model assumptions and predictions require validation from a combination of in situ, airborne and space-based observations of actual impacts.

The validation of predicted impacts caused by climate change is one of SAEON’s mandatory obligations as South Africa’s long-term environmental observation network. In turn, this research will inform and improve climate change modelling.

Historical environmental data sets

The ‘proof of the pudding’, so to speak, in terms of the impact of climate change is best revealed by analysing environmental data collected over long time-scales. Practically it means that if you want to start an environmental monitoring programme today, you will only be able to validate climate change impacts after some decades of observations.

It is for this reason that SAEON is continuously collating and exploring historical environmental data sets and re-commissioning relevant historical environmental observation systems.

A prime example of the value of historical data sets and re-commissioning observation systems has just been published in the prestigious Proceedings of the National Academy of Science by Slingsby, et al., which is accessible at https://t.co/c8esXMqyOV. This work is based on the periodic resampling of vegetation survey plots in the Cape of Good Hope section of Table Mountain National Park.

The climate is typically Mediterranean, with dry summers and wet winters, and the local fynbos vegetation forms part of the unique Cape Floristic Region, a Global Biodiversity Hotspot which is entirely constrained to South Africa.

It is generally accepted that plant diversity in fynbos is maintained by a fire cycle of 10-50 years. Slingsby et al. provide evidence that climate change has caused increasingly prolonged hot and dry periods, and where these periods have followed fire events, post-fire regeneration has been retarded and plant diversity has been reduced significantly.

These findings would not have been possible without the efforts of the late Hugh Taylor, who originated this vegetation survey in the 1960s. At the time, he would have been unaware of the advent of climate change.

The fact that his work has lately found new meaning is again a signal to decision makers that the termination of well-run environmental monitoring programmes should not be considered lightly. Long-term data often gather compounded interest over time and could facilitate quick answers to new and unforeseen environmental problems arising over time.

Decision-makers should therefore not just be cognisant of the long-term outcomes of their decision to terminate a monitoring programme, but in order to minimise unforeseen negative impacts also accept responsibility for archiving the programme’s accumulated data and metadata securely for possible future uses.