Low lying coastal areas are in general disproportionally the location for both urban and environmental disasters, and climate change looks like adding to the woes of people living in such areas. The rising tides expected as a result of climate change will increase the flood risk to low lying areas, and this risk will be further enhanced by the increasingly stronger tropical storms that are expected. In this post I will use data published in a study by McGranahan et al (2007) to explore settlement patterns in low lying coastal zones and thus provide an insight into the number of people that any rise in sea level is likely to have an impact upon.
Low lying coastal areas have long been seen by humans as favourable locations for settlements as they provide a large number of important resources as well as enabling travel and trade. McGranahan et al (2007) explain that the rise of colonialism and the subsequent rise in international trade resulted in a boom in the growth of low lying coastal settlements. However, while coastal locations can be seen to have a number of favourable attributes they are also very vulnerable to flooding, especially when high tides coincide with storm surges or high river flows. With respect to flooding it is the poor which are most vulnerable as while the wealthy can choose to locate in the more suitable areas, away from the threat of rising tides, the poor are often forced to settle on flood plains as cannot afford to locate elsewhere.
By overlaying geographic data layers McGranahan et al (2007) where able to calculate the size of the population living in the low elevation coastal zone for 224 countries as well as the land area which the LECZ accounted for. The LECZ was defined as “land area contiguous with the coastline up to a 10-metre rise elevation” using satellite radar topography measurements. Immediately it can be seen that as sea level in the 21st century is only expected to rise maximum of 0.59cm this leaves a large margin of safety, however, the authors justify this definition as sea level rise and storm surges can affect people living well above the sea level.
Globally this study calculated that while the LECZs contain 2% of the world's land they account for around 10% of global population, therefore showing how disproportionately high settlement in these areas is. Of all regions it is the small island states which have the largest share of their land in the LECZ; the Maldives, Tuvalu, Marshall Islands, Cayman Islands and the Turk and Caicos have over 90% of their land in this zone.
The countries with the greatest population living in the LECZ are China, India, Bangladesh, Vietnam and Indonesia. These five countries account for around three quarters of people living in the zone with China alone having 143,880 citizens in such areas. However it is more important to look at the percentage of the total population of each country living in the zone. Of the aforementioned top five, both Bangladesh and Vietnam have a large proportion of their population living in these zones, the figure for Bangladesh is 55% and Vietnam 46%. This means that in Bangladesh there are 62,524 people living in the LECZ and in Vietnam there are 43,051. This illustrates well that it is not just small islands at risk due to sea level rise but much larger countries where the number of people at risk is much greater. For these countries the idea of trying to move the population out of the zone is one that would be extremely difficult to execute due to the large scale of the endeavour. In addition while the LECZ for China only accounts for one-fiftieth of its total land area, in Bangladesh this figure is two-fifths and thus finding somewhere to relocate these people to is much more difficult.
Even more worrying is that even in the face of sea level rise, in many countries the size of the population living in the LECZ is expanding, due mainly due to economic growth which is driving movement to favourable urban coastal locations.
Overall it can thus be seen that there are large numbers of people globally that are extremely vulnerable to sea level rise and that the threat posed is not simply confined to those more limited populations that inhabit small islands. It therefore highlights the importance of tackling the issue of climate change and also highlights the need for global collaboration in planning for a worst case scenario. I think the idea of global collaboration is key to this issue as many of the countries likely to be affected by rising tides are of lower income and it is therefore unlikely that alone they will have the resources to tackle what is such a large threat. It is also important that action is taken as soon as possible to implement adaptive measure, because, as I have mentioned before in this blog, the idea that mass migration is the solution to this problem is extremely unfavourable with those most under threat. In addition as shown in this post, migration is an extremely large task which would involve relocating not just a few thousand but hundreds of thousands of people.
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