Coastal Environments and Global Change

masselinkRating: ★★★★☆

Gerd Masselink and Roland Gehrels. eds. 2104. Coastal Environments and Global Change. Wiley. ISBN 987 0 470 65659 4.

“I must go down to the sea again…” Coastal areas – sources of enjoyment, wonder, human activity and, of course, highly dynamic geophysical and biological systems. Coasts have always been a major attraction to people but now, the pressure is so great in some areas that the ecosystem health of the area is under threat. This might be less obvious in a crowded nation like the UK where coasts have been a central feature but not part of everyday life for most, but in Australia – a vast continent where the vast majority of people cling to a tiny coastal margin rarely greater than 50km – coastal change is a real issue. Local authorities buy up beachside homes to address erosion concerns and the recent potential de-listing of the Great Barrier Reef, one of the most iconic on the World Heritage List. There’s no shortage of texts looking at this topic, but far fewer take a trans-disciplinary look from the environmental perspective  we see here.

The basic premise of the text is that it looks at coastal systems, shows how global climate change might alter it and how we might manage that situation. In so doing it seeks to put coastal change in a more theoretical perspective than other texts. The opening chapter might start with the usual idea of defining coasts and processes (as well as defining basic terms) but it soon goes on to consider the main paradigm – the morphodynamic model. Essentially this is a simple input-output model where inputs would be external energy forces (winds, waves etc.) which, along with the geology of the area, shapes the hydrodynamics, sediment transport and morphology of the coastal zone. This theoretical model is backed by a range of models that can be used to test coastal changes. Subsequent chapters look at individual topics, studying their basic processes and noting how change might affect them, starting with sea level. Of course, sea level is almost an oxymoron, so it makes sense to start with definitions and how one can observe and make some statements about relative changes (since this is crucial to addressing climate-induced sea level change). These ideas are then used to consider sea-level change since the Quaternary. Sea level is an energy input and one of the most obvious along with tides and currents. These have to act on a surface and so the geology of the coast, our next area of study, is crucial. It’s not just rock types but the tectonic processes involved, including plate tectonics. Coastal geology and sediments shape the coast but they also exert negative feedback on coastal energy. By the next chapter, we are back to drivers of coastal change – waves and tides. As such, these forces won’t be affected by climate change but the factors upon which they depend e.g. water depth, will be which illustrates how climate change could affect aspects far beyond the obvious.

From this point onwards, the contributions focus on one aspect per chapter. The idea of mixing the theory of formation with the implications of change are maintained. The first two in this set examine the roles of storms, tsunamis and coastal groundwater. The former create sudden and devastating effects that are very difficult to respond to (as we have seen in the Boxing Day Tsunami and the events at Fukushima); the latter might be slower but the effect can be considerable. If these examples show how water regimes can be altered, then the next three chapters focus on the movement of sediment and the impact that can have. Beaches, dunes and barriers are all the result of sediment transport and deposition, aerial and submarine. They also share a certain fragility – all are composed of unconsolidated sand – and an importance to human activity. It is also made abundantly clear that changes in sea level as a result of global warming will have significant effects. Movement of sediment is a key part of coastal morphodynamics but the impacts are not just on the topography. Tidal flats, salt marshes and mangroves all rely on sediment transport for their existence. A product of calmer waters allowing finer sediment to be trapped, these ecosystems are also crucial to the well-being of numerous key species. Any changes would be correspondingly serious for ecosystem health and productivity. Also products of sediment movement, estuaries, inlets and deltas have provided shelter and productive areas for millennia. Their finely balanced structures require constancy to avoid breakdown. Just as sensitive, but in different ways are the last three cases mentioned here. High-latitude coasts are shaped as much by ice as by water but, with the exploration of the high Arctic now in full swing, these areas will soon be under threat from a range of human activities. Rock coasts might be less vulnerable (and certainly more common with about 80% of the world’s coasts so classified) but they are also less understood. The basic ideas of erosion and transport are well known but, after that, we have far less idea of the impact of climate change than we might need. It’s clear that much more research needs to be done. It’s the exact opposite with corals reefs, our last case. These areas have been well studied and are some of the more iconic marine views. However aesthetic they might be, they are still extremely vulnerable as the cases noted at the start of this review show. A final chapter summarises all the key points – drivers of changes and our possible responses.

The value of this text lies not so much in the topic it covers (although it covers considerable ground) but in the manner of its coverage. There are any number of books that describe the coast and spend more of their time looking at human impact. This ignores the key point that coasts are first and foremost, geomorphological features. To  make truly good decisions about coastal use you need to appreciate how the areas were formed and what the most important aspects are. This is where this text comes in. The topics are not just described but explained. The environmental science of each one is carefully noted. Theoretical models are used where needed and copious diagrams and examples demonstrate how real-world cases work. The references for each chapter (following a compact summary) are not only  succinct but annotated so the reader can see which papers are worth finding first. At a time when it seems a snapshot of coasts is all that is needed, this text comes along and provides far more useful detail. The range of topics is very impressive – there are no obvious gaps. to help learning, there’s a companion site. Overall, it’s a most impressive text – one of the best looking at the issues of coastal landscape development from every angle. If we are to face significant issues for climate change then texts like this, demanding a good grounding in the topic, will be needed to show what we might be able to do.

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