Unfortunately all good things must come to an end, and with the deadline for this blog looming it is time to wrap it up!
Having come into this blog with a reasonable understanding of SLC, I think I have come to appreciate how large the impacts of SLR could be. The processes and causes of SLC are now well understood however it is clear that uncertainty about the rate and magnitude of the individual contributions to SLC mean that not enough action is being taken to mitigate against SLC (apart from some countries... Well done the Netherlands!). This piece makes an interesting point about the link between uncertainty and inaction, while there is uncertainty around SLR it is definitely happening, the uncertainty is quite how bad it will be...
Seeing how close so many people in Bangladesh and other places around the world are to being forced to migrate as a result of SLR it is going to become an increasing pressure on decreasing land mass. I shall leave you with this graph from the IPCC projecting SLR by 2100 under varying emissions scenarios. I'm slightly more positive today about the likelihood of emissions reductions following the news that China is about to plough $361 billion into renewable energy by 2020. So hopefully China's example will be followed, emissions will begin to fall somewhat, and we will be looking at better scenarios in the next IPCC report... Although some studies, particularly those using the semi-empirical modelling approach to SLC (e.g. Rahmstorf, 2007) project it could be much more by 2100, kinematic constraints on glacier melting suggest it will be no more than 2 m by 2100.
The potential rise in sea level could be devastating and as I contended in my first post, I still believe that SLC is one of the 'quiet' agents of Climate Change and far more awareness of the potential problems it will cause is required. As the Netherlands have showed, effective mitigation is possible but before people realise how compromising SLC can be, it could already be too late. Try and be prepared just like the Statue of Liberty is (below)!
A slightly backwards post today, the film below is quite long, but gives an excellent introduction to the problems Bangladesh is having with Climate Change and particularly SLR. For those without the time to watch the film the main body of the post is below:
So why so much interest in Bangladesh? As the film suggests Bangladesh is stuck in the middle of SLR and flooding by its great rivers due to increased melting in the Himalayas as a result of climate change. It is often cited as the country most at risk of Climate Change, and essentially the majority of the country is one large floodplain (see below).Karim & Mimura, (2010) find that only a small rise in sea level could be catastrophic to significant areas of the coastal zone, and similar to the USA as mentioned in my recent post, storm surging during tropical cyclones could exacerbate this effect. From the map below it is clear that any SLR could lead to catastrophic flooding.
As I mentioned in my post on groundwater depletion, the subcontinent is one of the areas that undertakes a lot of groundwater extraction which can lead to SLR. This is a further pressure on the country meaning SLR could have a greater effect with land subsidence leading to more area becoming at risk of SLR (Brammer, 2014). The majority of Bangladeshis rely on agriculture for their income, running subsistence farms. With the projected loss of land expected to especially hit agricultural areas, people will be squeezed out of their livelihoods (Dasgupta et al., 2007). Bangladesh at least has begun to implement a National Adaptation Programme of Action (NAPA), based on UN standards to try and have a country wide project to mitigate against climate change. However as one of the Least Developed Countries with a GDP/capita of just $1,211, they lack the funding to implement large schemes such as those seen in the Netherlands or other developed countries. Therefore as outlined in the NAPA it is likely that Bangladesh will be forced to rely on aid to implement any adaption or mitigation programmes. This raises the question which I have not touched on too often: the main contributors to the climate change that is causing SLR. Bangladesh has contributed very little to climate change in terms of greenhouse gas emissions, but will be one of the first countries to feel the catastrophic effects. Considering projections suggest 17% of the land area is expected to be submerged by 2050, displacing 18 million people in the process, this is a ticking time-bomb. The response of the government is considered by many to be inadequate, with dredging programs and building of levees possibly exacerbating the situation. Pethick & Orford, (2013) present an interesting study that suggests rates of SLR in Bangladesh are not actually the critical pressure on Bangladesh, more that increasing population and the lack of available land, but that SLR will affect increasing numbers of people. They project SLR in Bangladesh to be significantly above the global average meaning even more people could be at risk in the near future. This is due to an expanding tidal range due to both GMSL rise and subsidence of deltas. The study appears somewhat doubtful in the magnitude of SLR but is clear in needing an integrated action plan to help adapt and mitigate to the problems Bangladesh face. This is supported by Brammer (2014) who believes SLR at its current rate will not make a massive difference to Bangladesh but population pressures are again the critical problem. For me it is apparent that population pressures are crucial in Bangladesh but the studies still downplay the potential impacts of SLR; many other countries have population pressure but Bangladesh's problem with SLR means it is one of the most at risk and SLR will continue to compound it.
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.
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.
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!
