Coastal environments and global change / Прибрежная среда и глобальные изменения

At the outset of this book, it is important to articulate clearly what we mean by ‘coast’, because the term means different things to different people. For most holidaymakers, the coast is synonymous with the beach. For birdwatchers, the coast generally refers to the intertidal zone; while for cartographers, the coast is simply a line on the map separating the land from the sea. Coastal scientists and managers tend to take a broader view.According to our perspective, the coast represents that region of the Earth’s surface that has been affected by coastal processes, i.e. waves and tides, during the Quaternary geological period (the last 2.6M years). The coastal zone thus defined includes the coastal plain, the  contemporary estuarine, dune and beach area, the shoreface (the underwater part of the beach), and part of the continental shelf and, in areas of isostatic or tectonic uplift, fossil raised shorelines (Fig. 1.1). At a first glance, it seems rather arbitrary and perhaps odd to take such a long-term view of the timescale involved with coastal processes and geomorphology. However, as we will see later (Chapter 2), the Quaternary was a period characterized by significant changes in sea level. In the past, eustatic, or global, sea level has been considerably lower than at present (>100m) during cold glacial periods, but also somewhat higher (up to 10m) during some of the warm interglacial periods. This implies that coastal sediments and landforms have the potential to extend considerably beyond the zone of contemporary coastal processes. In areas of former glaciations, where isostatic processes have caused crustal uplift, fossil coastal landforms can be found far above the present shoreline (Fig. 1.2a). Similarly, in tectonically active coastal areas, fossil shorelines can also be significantly displaced (Fig. 1.2b). In a lateral sense our definition means that the coastal zone can span hundreds of kilometres, especially in areas with broad continental shelves and shallow seas. For example, Fig. 1.3a shows the position of the coastline in northwest Europe during the last interglacial when sea level was several metres higher than today. <...>