Sea level rising, but islands growing...?!

A couple of weeks ago I talked about how many island nations were at serious risk of inundation if sea levels rose. However there has in fact been some evidence that seems to have contradicted this! It has been argued that these islands are in fact growing! But how could this be possible, after having seen all the other existing evidence, pictures, and videos that clearly show how much of a threat the waters are to these islands?

A recent study by Kench and Webb (2010), where they used historical aerial photos and satellite images, has shown that 23 out of the 27 central Pacific islands studied either retained the same land area, or actually increased in size over the last 19-61 years, whilst the sea level rose by 2mm during this same period. (Edwards, 2010). 

Eroded coral debris had in fact been pushed back up towards the coasts by a mixture of wind and strong waves due to changing weather patterns  - Kench claimed that this showed how the islands were coping with the changes (Daily Mail, 2010).

So this study has given us a completely different perspective on sea level rise, and really makes one think about what other changes are taking place alongside it. Hunter made a good point by mentioning other issues which may affect this further, such as ocean warming, and acidification (Daily Mail, 2010).

There are clearly a number of different forces acting upon global ocean patterns and these small islands. Sea levels may be rising, but I think that in order to determine the fate of these islands, it depends on which forces have the greatest impact. The strength of the sea itself may be stronger and more destructive in some areas compared to others. Kench believed that the islands are simply moving with the changes. (Daily Mail, 2010). 

The diagram below is just an example that depicts changes in reef island characteristics of a selected part of Tuvalu (Funafuti Atoll) from 1984-2003.

It shows how these islands have altered their shape over this period of time.

However, one point to note with this study as a whole was that it explored Pacific reef islands; it does not account for other parts of the world, different coastlines, or even the other oceans and associated islands – sea level rise does still pose a threat to many other areas of the world and so the findings here cannot be generalised. Just thought it was interesting though, as the evidence does seem to legitimately show the islands that were studied have grown! This is still quite a fresh discovery, and I think more studies are required to explore these findings, and to show us further evidence that this really is the case.

References

Anonymous (2010) ‘Low-lying Pacific islands 'growing NOT sinking' as sea levels rise’, Daily Mail: http://www.dailymail.co.uk/sciencetech/article-1283669/Low-lying-Pacific-islands-growing-sinking-sea-levels-rise.html#ixzz2DeAXQ4Qr

Edwards, T. (2010) ‘Pacific islands ‘growing not sinking’, as sea levels rise’, The Week: http://www.theweek.co.uk/politics/14185/pacific-islands-%E2%80%98growing-not-sinking%E2%80%99-sea-levels-rise#

Kench, P. & A. Webb (2010) The dynamic response of reef islands to sea-level rise: Evidence from multi-decadal analysis of island change in the Central Pacific, Global and Planetary Change, 72 (3): 234-246 http://www.pacificdisaster.net/pdnadmin/data/original/SOPAC_2010_The_dynamic_response.pdf

New York, New York

The Big Apple. Recently hit by “frankenstorm” Hurricane Sandy. Something this article mentioned caught my attention. The storm resulted in sea levels reaching 14 feet higher than the average low-tide mark (9 feet higher than the high tide average). But the danger isn’t the actual surge, but the return to normal – the high water mark has changed. The frequency of such storms is likely to increase due to warming of waters – sea level rise means that these surges will have even more of an impact in the future (Childs, 2012). It has now been suggested that New York should invest in the building of storm surge barriers, to prevent such destruction in the future. 

So what can New York expect over the coming years in terms of rising sea levels? A study by Horton et al states that sea level projections in this region are higher than overall global projections. They attribute this, partly, to the gradual subsiding of this area by around 3-4inches per century. The weakening of the Gulf Stream will also impact this region (US northeast coast) and contribute to rising sea levels. The possibility of more frequent extreme events (such as Sandy) will also lead to more flooding. (Horton et al, 2010).

The video from this site has emerged following Sandy, where we find out the opinions from some New Yorkers themselves. (sorry I could not get it to embed within this post, but it's definitely worth watching!)

The question, is safety vs. beauty... would they rather be safe from future threats, or prefer a better view from their windows?

If it were up to me, I would definitely advise them to take action as soon as possible. The threats are imminent and seem to only be getting worse. It is expensive to build the infrastructure, however it will be a worthy investment, and save, at least to some extent, the future of New York.

References:

Childs, C. (2012) Our Latest High-Water Mark, The New York Times (WWW) http://www.nytimes.com/2012/11/03/opinion/our-latest-high-water-mark.html

Horton, R. et al (2010) Climate Observations and Projections, Annals of the New York Academy of Sciences, 1196: 41-62

PBS (2012) Protecting New York From Future Superstorms as Sea Levels Rise:

 http://www.pbs.org/newshour/bb/climate-change/july-dec12/sandy_11-20.html

Rosenzweig, C. and W. Solecki (2012) Rising Sea Levels Are Serious, The New York Times (WWW) http://www.nytimes.com/roomfordebate/2012/11/02/should-new-york-build-sea-gates/we-must-take-rising-sea-levels-seriously?smid=tw-roomfordebate&seid=auto

More on Venice...

What comes to mind when I say Venice?  For most, I’d assume a romantic, picturesque, and pretty place, known for its canal system. But things are changing here in terms of its water level…

The relative sea level rose by 25cm over the last century (Pilkey, 2009). Flooding has increasingly become a common occurrence for Venice, and it is prone to progressive submersion over time. The picture below marks just how much water level has risen since 1792.

 (taken from Carbognin, 2009)

The particular threats that this region faces are flooding, erosion, and the permanent inundation of low-lying land. The exposure of the land to such high tides is known as ‘acqua alta’. These primarily occur due to strong winds around the Northern Adriatic Sea, creating a surge of water. (Barale, 2010)

Venice is no newcomer to flooding events. They have constructed raised wooden pathways (known as ‘passarelle’) for times when footpaths cannot be walked on (Keahey, 2002). Additionally, during high tides, boats cannot travel down the canals, as they would not be able to pass under bridges.

One of the major flooding events that occurred was in 1966, where the tide was over 1 metre high, causing a lot of destruction, and eroding the coastline hence exposing and damaging coastal towns. Action has been taken to try and safeguard the city from acqua alta. They have become more frequent, and the risk of major events such as that of 1966, or even the flooding that occurred a few weeks ago, has increased.

The high tides cause damage to some of Venice’s construction – the salt water soaks into soft brick, and eventually can lead to its deterioration. Additionally, the waters damage some of Venice’s relics, and interiors also as the tides get higher and the water is able to seep through an increasing number of places.  

So they essentially need to prepare for the worst. A flood management system is still under construction and aims to be complete by 2014. But this is still 2 years away, and, especially after recent events, they need to act fast... 

References:

Barale, V. et al (2010) Oceanography from Space: Revisited, New York: Springer

(http://books.google.co.uk/books?id=hH2NkL_318wC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false)

Carbognin, L. et al (2009) Global change and relative sea level rise at Venice: what impact in term of flooding, Climate Dynamics, 35 (6): 1039-1047

(http://www.springerlink.com/content/f121075417614286/fulltext.html)

Keahey, J. (2002) Saving Venice From the Sea, Nova: http://www.pbs.org/wgbh/nova/tech/saving-venice.html

Pilkey, O. et al (2009) The Rising Sea, Washington: Island Press

(http://books.google.co.uk/books?id=U4JV91-gZZUC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false)