Important Data and Research Gaps for Robust Impact Analysis
In addition to their exceptional exposure to climatic hazards, small islands face additional challenges: climate science is so far insufficiently able to represent small islands in global circulation and impact models. Robust data for science-based adaptation strategies in the region remains an urgent need.
The current generation of Atmosphere Ocean General Circulation Models (AOGCM) used in the climate science community to project climate change usually provide a resolution of between 0.5 and 4°, depending on model and model components (Meehl and Bony 2011). Many island nations consist of multiple islands, smaller than the resolution of such models, therefore their signal within the oceanic environment is not adequately reflected within existing AOGCM. Regionalised climate data is so far limited, though down-scaling approaches to better represent island topography have recently been applied (Australian Bureau of Meteorology and CSIRO 2014). A recent study of aridity changes downscaled to small islands revealed the relevance of such approaches projecting mean drying of the order of observed inter-annual variability (Karnauskas et al. 2016).
Similarly, biophysical impact models to understand changes in agricultural yields or water availability, for example, are currently not able to fully represent island dynamics and regional priorities. Improved representation of Pacific Islands in biophysical models is further restricted through the limited availability of long-term data series of past observations, which are critical to calibrate models and provide robust projections of potential future developments (Australian Bureau of Meteorology and CSIRO 2014).
Many islands in the Pacific only rise a few meters above sea-level. The current vertical precision and accuracy of digital elevation models that are used to understand coastal exposure to rising sea-levels (see e.g. Hinkel and Klein 2009 on the DIVA model), is insufficient to capture the exposure that low-lying atoll islands face (Sampson et al. 2016): even a few centimetres delimit the difference between survival and constant flooding. In addition, larger waves and higher wave-driven water levels along atoll islands’ shorelines are projected in conjunction with sea-level rise, which may cause twice as much land to be flooded for a given value of sea-level rise than predicted by current models (Storlazzi et al. 2015). While the scientific knowledge base on climate change in the Pacific has constantly been increasing and data as well as regionalized studies are increasingly becoming available, an important restriction hampering progress that remains is the currently limited scientific capacity in the region. As a consequence, Pacific island issues are not well represented in the scientific literature and associated internationally recognised fora, such as the IPCC (Pasgaard and Strange 2013; Pasgaard et al. 2015).
