The Pacific nation of Tuvalu—long seen as a prime candidate to disappear as climate change forces up sea levels—is actually growing in size, new research shows.
A University of Auckland study examined changes in the geography of Tuvalu's nine atolls and 101 reef islands between 1971 and 2014, using aerial photographs and satellite imagery. It found eight of the atolls and almost three-quarters of the islands grew during the study period, lifting Tuvalu's total land area by 2.9 percent, even though sea levels in the country rose at twice the global average.
It found factors such as wave patterns and sediment dumped by storms could offset the erosion caused by rising water levels.The Auckland team says climate change remains one of the major threats to low-lying island nations.
But it argues the study should prompt a rethink on how such countries respond to the problem. Rather than accepting their homes are doomed and looking to migrate to countries such as Australia and New Zealand, the researchers say they should start planning for a long-term future.
https://phys.org/news/2018-02-pacific-nation-bigger.html
Three and four years ago I suggested a similar process:
ReplyDeleteZephyr López Cervilla Jan 27, 2015
A question that I've never seen to have been addressed is the effect of sea level rise on the settlement of coastal and river sediments. I would expect a shift of the process upstream as a result of a precocious slowing of the velocity of the river flow. The slower the flow, the greater the amount of sediments that will settle.
Likewise, every flooding event would tend to pile more sediment deposits in the flooded areas as a result of a slower drainage, or alternatively, the flooded areas would extend upstream and more sediments would settle there.
This effect would be expected to be particularly relevant in deltas, such as the case of the Ganges Delta and upstream basin:
en.wikipedia.org/wiki/Ganges_Delta
en.wikipedia.org/wiki/Bangladesh
This process would explain how the present delta formed during or after the sea level rise that occurred at the end of the last glacial period and subsequent post-glacial period:
commons.wikimedia.org/wiki/File:Holocene_Sea_Level.png
commons.wikimedia.org/wiki/File:Post-Glacial_Sea_Level.png
<< The lower "figure shows sea level rise since the end of the last glacial episode based on data from Fleming et al. 1998, Fleming 2000, & Milne et al. 2005."[7]
"[A]t least one episode of rapid deglaciation, known as meltwater pulse 1A, is agreed upon and indicated on the plot. A variety of other accelerated periods of deglaciation have been proposed (i.e. MWP-1B, 2, 3, 4), but it is unclear if these actually occurred or merely reflect misinterpretation of difficult measurements. No other events are evident in the data presented above."[7]
"The lowest point of sea level during the last glaciation is not well constrained by observations (shown here as a dashed curve), but is generally argued to be approximately 130 +/- 10 m below present sea level and to have occurred at approximately 22 +/- 3 thousand years ago. The time of lowest sea level is more or less equivalent to the last glacial maximum. Prior to this time, ice sheets were still increasing in size so that sea level was decreasing almost continuously over a period of approximately 100,000 years."[7] >>
Source:
en.wikiversity.org/wiki/Hydromorphology#Sea_level
en.wikipedia.org/wiki/Last_glacial_period
en.wikipedia.org/wiki/Meltwater_pulse_1A
en.wikiversity.org/wiki/Radiation_geography#Sea_level
Presumably, 22 thousand years ago the coastal deltas would be found at about 130 metres below present sea level. As sea level began to rise, the coastal deltas moved upstream, filling up with sediments the lower stretches of river basins.
According to the lower graphic, between 8 thousand and 7 years ago, the sea level rise would have been of about 10 m, that's about one-meter rise per century. Did the coastal deltas regenerate at that pace? And the lower stretch of the river basins, were they filled with sediments at similar pace? This question could be answered by determining the age of the sediments at different depths and comparing it with the estimated sea level over that period.
I expect that if the sea level continues to rise, such process will occur in some extent over the next decades and centuries, whose intensity will be dependent (among other factors) on the amount of sediments carried by the flow of each river.
ReplyDeleteIf so, the land of coastal river deltas and nearby basins that is presently occupied by millions of people would progressively be covered by a layer of river sediments, thus countering at least partially the sinking of that land with respect to sea level.
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URL G+ posts source comment:
plus.google.com/+johncbaez999/posts/AKMU2D7ALfj
plus.google.com/+ZephyrLópezCervilla/posts/HXTZQNEDX9s
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sophie helfrich Oct 23, 2013
+Zephyr López Cervilla I feel so much better now! Tons of sediments driven by the Rhin will save the netherlanders from the sea. Or maybe our friends the sediments will stay for a while in these charming towns they have in Switzerland and Germany? If you have some other link showing how frequent collapse of industrial building in Dacca will save Bangladesh from permanent flood, please, let me know.
So, don't think I feel boried by this conversation, but I have a shovel to buy, in the very unlikely hypothesis of lost sediments invading my basement instead of going to Rotterdam.
Zephyr López Cervilla Oct 24, 2013
+sophie helfrich: "Tons of sediments driven by the Rhin will save the netherlanders from the sea."
— The reason why sealevel along the coast of Netherlands isn't expected to rise significantly isn't related to river sediments. It's caused by local factors and the effect is spread along all North Sea (as well as other areas).
As for the river sediments, in my opinion, those sediments would limit the loss of land area in those areas where the sea level would rise, such as in countries like Bangladesh (thanks to the sediments coming from the Ganges river).
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URL G+ posts source comment:
plus.google.com/+BetsyMcCall/posts/6G6FriqGrAz
plus.google.com/+ZephyrLópezCervilla/posts/DYipjjfA49y
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Zephyr López Cervilla Sep 23, 2013
Clearly, that extrapolation on the population affected by the sea level rose hasn't taken into account the effect of sedimentation on the coastline, estuaries and deltas. In many of those areas people won't have to move anywhere else because the land will be progressively covered with a layer of lime/mud/sand, thus effectively rising the height of the land surface above sea level.
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URL G+ posts source comment:
plus.google.com/+NatureNewsComment/posts/Eg7jxSBzqVz
plus.google.com/+ZephyrLópezCervilla/posts/DYipjjfA49y
plus.google.com - Ancient ice If the Greenland ice sheet completely melts, the sea will rise 7...
Ah Tuvalu; where roughly 16% of the GDP is from it's domain name.
ReplyDeleteApparently, the main export is Tugboats to Thailand; followed by frozen fish (which is only slightly more than the $5.5 million that Verisign pays them). Interestingly, this page does not list IP as a major export:
https://atlas.media.mit.edu/en/profile/country/tuv/