1992-2011 sea level rise For the period 1992-2011, global sea level was observed to increase at a rate of 3.1(±0.4) millimeters per year. This rate is the global average and can be thought of as resulting from all the locations measured on the surface of the ocean. If we limit the region to the area around the Philippines, the rate for the same period is 5.8(±0.6) millimeters per year. This variation is further complicated by regional ocean-atmosphere dynamics. Water is pushed across the Pacific toward the Philippines by what is known as the North Pacific Subtropical Gyre. It is the clockwise circulation of water around a high-pressure area in the northern Pacific Ocean basin that is due to the Earth’s rotation. Furthermore, trade winds blowing westward along the latitude of the Philippines help intensify the current that flows northward as it encounters the Philippine coastline. At the opposite side of the Pacific, water is pulled away from land, resulting in lower sea levels. Local factors also affect sea levels. Interactions between physiography, tectonic activity, inland tides, climate patterns, and weather effects influence water levels in a particular locale differently from other areas. Therefore, sea levels will vary from one coastal area to another depending on local conditions. Assuming that the rate of change of sea level around the Philippines for the period 1992-2011 does not change, we can expect waters to rise by at least 20cm in the next 40 years. Figure 1 shows the absolute rise in sea level around the Philippine coast by 2050. This is in addition to the current average water level at any one site. Notice the spatial variation; the highest expected are along the Pacific seaboard from Samar all the way down eastern Mindanao, the Zamboangas, and the island provinces of Romblon and Marinduque in the Sibuyan Sea. 20cm is equivalent to 20% of 1m or 3.3ft. That would equate to around 8inches of water. Assuming the same rate of increase in the next 50yrs, the total rise would be around 18inches or a foot-and-a-half. How much will that eat up on our coastlines around the country? What would the impact be on low-lying urban areas by the sea?
Posted on: Thu, 15 May 2014 02:30:57 +0000
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