GEOG40960 Coastal Risks

Academic Year 2023/2024

The coastal zone, often defined as land within 100 km of the ocean, constitutes about 20% of the Earth’s surface. By this definition, Ireland is almost totally a coastal landmass. Nearly all of Ireland’s population, and about 40% of the global population, lives in the coastal zone. Three quarters of Earth’s cities with a population exceeding 10,000,000 are coastal and, overall, 10% of the global human population lives on land at most 10 m above mean sea level. Coastal resources and the larger ocean economy, including fisheries, energy, shipping, culture and tourism, generate up to US$ 6,000,000,000,000 per year, accounting for up to 10% of global GDP and supporting nearly 300,000,000 jobs. The coast is home to species, habitats and resources that are crucial to the functioning of the marine ecosystem and to a significant proportion of human economic activity. For example, coral reefs are possibly the most biodiverse ecosystem on Earth, probably exceeding the biodiversity of tropical rainforests. Directly, food resources from coral reefs sustain about 1,000,000,000 people. However, corals provide both the structural and nutritional foundation of a marine food chain that encompasses 90% of all marine species – and over 50% of the human population relies on food from the ocean for their primary nutrition. However, the coastal zone is extremely sensitive to climate change and its broader environmental consequences.

At present, the Earth is in an interglacial period – a time of warmth between the more typical glacial periods that have defined the Quaternary Period, the last 2,600,000 years of Earth history. In that time, it is known that interglacial periods have been characterised by atmospheric CO2 levels twice that of a glacial period. However, because of anthropogenic greenhouse gas emissions, the Earth’s atmosphere presently has a CO2 concentration almost twice the natural concentration of the gas during previous interglacial periods. Consequently, both atmospheric and oceanic temperatures are rising. However, the ocean has absorbed more of the excess heat generated by anthropogenic greenhouse gas emissions than the atmosphere; even the top 5 m of the global ocean contains more heat than the entire atmosphere. Globally, this situation means that, as both atmospheric and ocean temperatures rise, the Greenland and Antarctic Ice Sheets, the Earth’s largest stores of freshwater, are melting at increasingly rapid rates and the volume of the global ocean is expanding. Consequently, sea level is rising, the atmosphere is becoming stormier and precipitation is intensifying. These impacts of anthropogenic climate change mean that the coastal zone is especially sensitive. Because problems such as coastal erosion, flooding, water resource stress and habitat loss have the potential to affect a huge part of the Earth’s natural systems, and the lives of billions of people dependent on them, a better understanding of the stresses imparted on our coasts by climate change is required now, as never before. In that context, this module has three broad aims: firstly, to introduce students to the coastal zone, its varying characteristics and processes; secondly, to identify the most pressing issues faced by both the natural and human systems supported by the coastal zone, and; thirdly, to introduce students to the integrated strategies being developed in coastal zone management, in an era of accelerating climate change and environmental sensitivity.