No abstract

Understanding anticipated climate-induced changes in the global wind-wave climate is paramount for sustainable development of coastal and ocean industry-operations, resources, ecosystems and for the mitigation of potential impacts on coastal settlements. Intensive research has been placed into global and regional wave climate projections over the past 10 years, but no systematic review has been conducted to date. Here, we present a consensus-based analysis of 91 published global and regional scale wind-wave climate projection studies to establish consistent patterns of impacts of global warming on the wind-wave climate across the globe. Furthermore, we critically discuss research efforts, current limitations and identify opportunities within the existing community ensemble of projections to resolve various sources of uncertainty amongst the sparsely sampled set of future scenarios. We find consensus amongst studies regarding an increase of the mean significant wave height ̅ s across the Southern Ocean, tropical eastern Pacific and Baltic Sea, and conversely, a decrease of ̅ s over the North Atlantic and Mediterranean Sea. Furthermore, we observe that projections of ̅ s over the eastern north Pacific and southern Indian and Atlantic Oceans lack consensus. Similarly, future projections of extreme s lack consensus everywhere, except for the Southern Ocean and North Atlantic. We note a distinct lack of research regarding projected

To study retention of waterborn larvae in a reef matrix we used a finite element unstructured numerical model with a minimum horizontal resolution of 150 m that can capture variability of currents on a spatial scale relevant to coral reefs in the Great Barrier Reef (GBR). Areas of high reef density (i.e. closely aggregated reefs) are poorly flushed because the prevailing currents are steered around and away from these regions, which is an oceanographic process called the 'sticky water' effect. The model showed that the sticky water effect leads to decreased flushing and a high exposure time in high reef density areas in the southern and central regions of the GBR matrix. In turn this generated hotspots of high self-seeding, and these hotspots existed under both calm weather conditions and wind conditions typical of those during the coral spawning season. Away from these areas, self-seeding was less likely to occur and larval replenishment would result mainly from connectivity between reefs located kilometers to tens of kilometers apart. The location of sticky water areas varied spatially within the reef matrix according to tidal and mean currents, local bathymetry and reef density (defined as the degree of aggregation by reefs). A simple analytical formula is presented that explains about ~70% of the variation in larval retention in both calm weather and windy conditions. Complex reef mosaics and the related sticky water effect may have significant implications on the fate of larvae, and thus on connectivity for coral reefs worldwide.

The accumulation of floating anthropogenic debris in marine and coastal areas has environmental, economic, aesthetic, and human health impacts. Until now, modelling the transport of such debris has largely been restricted to the large-scales of open seas. We used oceanographic modelling to identify potential sites of debris accumulation along a rugged coastline with headlands, islands, rocky coasts and beaches. Our study site was the Great Barrier Reef World Heritage Area that has an emerging problem with debris accumulation. We found that the classical techniques of modelling the transport of floating debris models are only moderately successful due to a number of unknowns or assumptions, such as the value of the wind drift coefficient, the variability of the oceanic forcing and of the wind, the resuspension of some floating debris by waves, and the poorly known relative contribution of floating debris from urban rivers and commercial and recreational shipping. Nevertheless the model was successful in reproducing a number of observations such as the existence of hot spots of accumulation. The orientation of beaches to the prevailing wind direction affected the accumulation rate of debris. The wind drift coefficient and the exact timing of the release of the debris at sea affected little the movement of debris originating from rivers but it affected measurably that of debris originating from ships. It was thus possible to produce local hotspot maps for floating debris, especially those originating from rivers. Such modelling can be used to inform local management decisions, and it also identifies likely priority research areas to more reliably predict the trajectory and landing points of floating debris.