Rising Sea Levels: Causes, Projections, Implications

11/17/20222 min read

Global mean sea levels (“GMSL”) increased by more than 6 centimetres between 1993 and 2014 (POST 2017).

Rising sea levels are caused primarily by sea waters becoming warmer and from the melting of glaciers and ice sheets (POST 2017), both of which are results of global warming induced by anthropogenic emissions of greenhouse gases (POST 2017).

As water heats up, by a process of thermal expansion, water molecules gain energy and move farther away from each, thereby causing them to expand and increase their volume (UoW). 40% of the GMSL rise is attributed to thermal expansion. 45% is a result of the melting of glaciers and ice sheets, of which half can be traced back to Greenland and the Antarctic (POST 2017). As Greenland loses surface ice melts at a faster rate than it accumulates snowfall, the volume of the Greenland ice sheet decreases (POST 2017). In Antarctica, ice loss is caused by ice shelves becoming thinner and/or disintegrating, a a result of warmer atmospheric air and increased sea surface temperatures -- as this happens, more ice sheets flow toward the ocean (POST 2017).

Future GMSL depends on several factors including future rates of greenhouse gas emissions, and their associated temperature increases (POST 2017). However, current projections envisage that GMSL will between 43cm and 84cm by the year 2100 (Oppenheimer et al 2019). In the UK, the relative sea level (was estimated in 2009 to increase by 190cm by 2100 (POST 2017).

If GMSL continues to rise, the UK can expect increased coastal erosion, more frequent storm surges and coastal flooding, as well as more regular extreme sea level events (POST 2017).

In the next 50 years ago, more than 2,000 coastal properties could be destroyed due to coastal erosion (POST 2017). Further, the existing coastal flood defences installed along 200km of coastline could fail if RSL hits 50cm, and if so, approximately 312,000 properties could be exposed to floods and surges.

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