Maps, laws and planning policy: working with biophysical and spatial uncertainty in the case of sea level rise

Rapid sea level rise over the 21st century threatens coastal settlements and populations worldwide. Significant land-use policy reform will be needed to mitigate exposure to hazards in the coastal zone. Sea-level rise maps that indicate areas that are potentially prone to future inundation are a valuable tool for policymakers and decision makers. However, errors, assumptions, and uncertainties inherent in spatial data are not often explicitly recognised or communicated. In 2011, the state of Queensland, Australia, published a series of ‘state of the art’ sea-level rise maps as part of its coastal planning regime. This article uses the Queensland coastal planning regime as a case study to explore how errors, uncertainties and variability in physical, geographical and biological processes in the coastal zone pose challenges for policy makers. Analysis of the case study shows that the use of spatial data in sea-level rise policy formulation is complicated by the need to: (1) acknowledge and communicate uncertainties in existing and projected rates of rise; (2) engage in site-specific mapping based upon best available scientific information; (3) incorporate probabilities of extreme weather events; (4) resolve whether coastal engineering solutions should be included in mapping; (5) ensure that mapping includes areas required for future ecosystem migration; (6) manage discretion in planning and policy decision-making processes; (7) create flexible policies which can be updated in line with scientific developments; and (8) balance the need for consistency with the ability to apply developments in science and technology. Scientists working with spatial data and governments developing and implementing coastal planning policies can recognise, communicate, and seek to overcome uncertainty by addressing these factors