Tropical Storms and SLR: The Perfect Storm?

In my introductory blog I mentioned how SLR was affecting the damage caused by major hurricanes including Sandy (2012) and Matthew (2016). Now as a Christmas present to my dear readers I will (finally!) address this and show how the small incremental change of SLR is having a large effect on the damage that these hurricanes are causing.

Along with the projected increase in cases of extreme (category 4 & 5) hurricanes in the future as a result of climate change (Goldenberg et al., 2001), SLR is projected to increase which means that storm surges associated with hurricanes will inundate further affecting more and more infrastructure and homes. A significant amount of the damage caused by Hurricane Matthew has been attributed to storm surging, while Hurricane Sandy saw large parts of New York under water. 

Flooded taxis in New York following Hurricane Sandy. Source

There is an element of luck to how bad a storm surge will be, if the peak surge coincides with high tide then that can raise the height of the surge by many metres. This occurred during Hurricane Sandy in New York, causing significantly more damage than had it been at low tide. The acceleration in SLR (see below) is being particularly affected by thermal expansion with a further acceleration being reported in the last decade (see below), disproportionately so on the Atlantic Coast of North America (Rietbroek et al., 2016). This is thought to be due to a combination of meltwater fingerprinting and changing ocean cycles as I have indicated in earlier posts, the regional signal of SLC is critical in some areas.

Source

Hurricane Matthew caused up to $6 billion of damage in both Haiti and America, with the state of North Carolina experiencing $1.5 billion worth of damage alone. SLR contributes significantly to this due to the rising of the base sea level, so what would have caused less flooding 100 years ago now causes significant amounts of flooding (see video below). Despite this officials in the Florida Department of Environmental Protection are not allowed to use the phrases ‘climate change’ or ‘global warming’ . Apathy to this issue will allow for SLR to continue to affect America, and despite this Florida, one of the most at risk areas doesn’t have a state-wide action plan to deal with climate change. As I showed in last week's post, The Netherlands' well-defined and wide ranging action plan significantly mitigates the effect SLR can have therefore it is very surprising that Florida don't have an action plan that could save lives and billions of dollars in the long run.

  

It is clear that hurricanes can cause significant coastal flooding which can be exacerbated by SLR. A paper by Woodruff et al., (2013) compared present day situations to early Holocene records where rapid SLR was experienced. Using past conditions can act as an analogue for the present and the future so to look at periods where similar conditions were experienced has certainly informed on the potential future tendencies They found that during the early Holocene SLR meant low-lying coastlines had low resilience to storm impacts. In addition they found that the worst storm surges are caused when winds are highest, considering storm activity is projected to increase with the strongest storms having the greatest effect (Zhang et al., 2001), it is likely that with SLR and increased activity coastal flooding could worsen. This is particularly likely in low-lying areas such as Bangladesh, where inundation of significant land area has been modelled to be very likely by 2050 (Lin et al., 2012). The suggestions of Woodruff et al., 2013 appears valid as it is very likely in the future a combination of SLR and increased storm activity could significantly affect coastal areas. This is supported by Mousavi et al., (2011) who modelled that even by 2030 as a result of SLR, surges could be up to 0.3 m higher in the USA, and by 2080 0.8 m higher. Considering they found this to likely be on the lower end of estimates due to unmodelled uncertainties, the effects of storm surging and the economic and human damage that it can bring will be significant.

Source

It is apparent that SLR is having a significant effect on the destructiveness of storms. Raising the base sea level means storms like Sandy and Matthew cause far more damage than they would have 100 years ago and with projected increased storminess, governments need to get a handle on the potentially catastrophic effects. So Florida, get your act together!

An introduction..

Hello! Over the coming months I shall be writing a blog that will hopefully inform and discover about Sea Level Change. So why am I looking at Sea Level Change and why is it important?

• Half of the world’s population live within 60km of the sea and this is growing
• Approximately 5% of the world’s population live at an elevation of under 5 metres
• The rate of sea level change is greatly affected by anthropogenic warming of the climate
• According to the IPCC global mean sea level is rising at an unprecedented rate (3.2 mm/yr)
• With current rates of warming (4°C by 2100) up to 760 million people could find the land they live on submerged.

Flooding in Venice in 2008, will this keep happening?

These are just a few of the reasons that sea level change appears to be a crucial factor of Global Environment Change. It is clear that sea level change has the potential to be one of the biggest threats to mankind. However having given in the above bullet points some doomsday like facts a greater understanding of the mechanisms that drive sea level change will be required. The estimate of 3.2mm/yr for global mean sea level rise is both informative yet on another level useless. Yes it shows that across the globe sea level is rising, but as a global average doesn’t tell you how the rate of sea level change is in fact very non-uniform. It is important therefore not to look at simply mean sea level change, but relative sea level change as in some areas sea level is in fact falling in some areas.

I am interested in learning more about sea level change as I perceive it as one of the ‘quiet’ forces of anthropogenic climate change; little by little it is having an effect. This has been shown with the very recent Hurricane Matthew where storm surging was the major cause of damage on the US East coast, exacerbated by the rise in sea levels. In addition the devastation caused by Hurricane Sandy in 2010 was greatly influenced by the rises in sea level, as flooding may have not been as extensive. However this often receives little coverage following large events such as these when in fact it is one of the crucial factors in causing damage and destruction.

Photo showing the storm surge from Hurricane Matthew in Georgia, US

During this blog I will aim to understand the mechanisms and processes that govern sea level change, its potential effects and the areas most at risk from sea level change. So stay tuned!