Sea level rise in the Pacific
Written, edited and directed by Greg Downey.
Sea level rise will affect the Pacific Islands long before they go under the ocean -- they may become inhabitable before they sink because of the problem of water shortage.
By Greg Downey, 2015
By the end of the Twenty-First Century, the Intergovernmental Panel on Climate Change estimates that global warming could lead to an increase in global sea level of between 18 and 59 centimetres. Increased sea levels pose extreme challenges to coastal communities, especially in the Pacific, where island nations are particularly vulnerable.
Sea level rises with climate change for a number of reasons, most importantly, glaciers and polar ice caps melt. As the temperature warms, glaciers melt, and millions of tons of water that is locked on land in places like Antarctica and Greenland runs into the oceans. In fact, careful study of these large stores of ice make some scientists worry that sea level rise over the next fifty to eighty years could be even greater, as the glaciers may be melting faster that temperature change alone would predict.
At the same time, water in the oceans also expands when it warms. About half of the sea level change that we have already witnessed is due to this thermal expansion rather than to glacier run-off.
Even if only the most conservative estimates are accurate, sea level change will disrupt many people’s lives. The global population is disproportionately distributed along the continents’ coasts. Major cities such as New York, Mumbai, Jakarta, and Guangzhou have millions of residents living in areas that will face increased threat of flood. Miami is already struggling with the effects of sea level rise, which threatens some of the most valuable real estate in this Caribbean capital.
Change in sea level can be devastating, especially to low-lying coastal regions. The islands of the Pacific are particularly vulnerable, in part, because so many of those islands are scarcely above sea level. An increase in sea level of one meter could place 80% of Majuro atoll in the Marshall Islands and over 12% of Kirabati under water. 77,000 km of coast lines across all the islands will be affected.
But Pacific nations are also vulnerable because they are so dependent upon coastal areas economically. Warmer oceans, especially as they acidify due to carbon absorption, may cause coral bleaching or deplete reefs that provide crucial coastal breeding grounds for fish. Since the beginning of the industrial revolution, the oceans have grown more acidic, making it harder for tiny corals to build their skeletons by dissolving calcium carbonate.
For a country like Tuvalu, with only ten square mile (26 square kilometres) of dry land in total, even a small change in area can stress the population and force them to migrate. Local food production is essential to support the population, so changes in the available land can make life on these islands much more difficult.
Because coral atolls are dynamic, however, growing and changing shape as tides bring ashore new material, just as they also erode other parts of these islands, some Pacific Islands will actually change in size due to sea level changes, perhaps even adding some area as the sediment from coral reefs gets washed ashore.
But the effects of a rise in sea level will strike these communities even before the oceans wash over the land. Sea level rises mean that high tides as well as the storm surges that accompany hurricanes will reach further inland, doing more erosion damage, fouling wetlands, and flooding coastal areas. When king tides or storm surges recede, they will leave behind soil with more salt and fewer nutrients.
As soils become more saline, farmers on small islands have to adapt, trying to find ways to keep the salt out of gardens or raise plants above the level of the increasingly-saline ground water. To grow pulaka, for example, the starchy root that is one of the most important staples in the traditional diet of Tuvalu, farmers are trying to find ways to fight salt, including planting the root in compost-filled, concrete-lined pits (for more, see National Geographic).
Increased sea levels leads salt water to infiltrate the porous stone layers under Pacific islands, the same layers that hold ground water vital for agriculture and drinking water. Sea level rises lead to fouled wells and groundwater increasingly unsuitable for human use or agriculture.
With changes in rainfall patterns also likely from climate change, the increasing salination of groundwater may give rise to an arid irony in some Pacific Islands: sea level rise may force some Pacific Islanders to flee their homes, not because the waves are at their front doors, but because they run out of drinkable water.
Sea level rise may paradoxically bring desert to some islands.
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Qin, D., Plattner, G. K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., ... & Midgley, P. M. (2014). Climate change 2013: The physical science basis. T. Stocker (Ed.). Cambridge, UK, and New York: Cambridge University Press.
The idea for this video came from discussions with Sama Penaia, Johanna Beasley, Christina González Martín, and Tomasi Domomate.