Sea Level Rise, London
Sea level rise is one of the most serious consequences of climate change. This is largely due to the fact that large concentrations of people live on the coast, approximately at sea level. There is also a public communication issue here as the science talks of mm per year. It’s hard to get excited about 3.1 mm/yr (1993-2003, IPCC) when tides move metres in hours. The current rate is probably closer to 4 mm/yr given the acceleration in ice-sheet melt since then. Instead of being scientific, let’s be dramatic, let’s look at London today.
It’s actually Sunday afternoon on the 31st January 2010. I happened to be in Putney on the banks of the river Thames and was surprised to watch the river come over its banks and flood the nearby road. By the look of the parked and flooded cars I wasn’t the only surprised onlooker that afternoon.
I managed to take a few photos on my phone. The photos were taken between 15:08 and 15:12, high tide was officially 15:16 in Putney that day so this was pretty much it. A Putney tide table is available here: http://tides.rjen.me.uk/
The site contains a tide table for Putney Bridge, just a few hundred metres from where the photos were taken (visible in the second shot). The table says the projected high tide height was 7.4 m, certainly a high tide but the projection for the following day was 7.5 m and scanning down the table every ~28 days high tides exceed seven metres for a few days at a time. I don’t believe this high tide was contributed to by particularly strong easterly winds, low air pressure or high proceeding precipitation in the Thames catchment area. This is normal, London and its millions of inhabitants live at sea level. There isn’t much margin to accommodate the potential 1 m (or possible as much as 2 m) sea level rise the science is indicating could occur by 2100, 90 years from now.
The only point to keep in mind is that this road, The Embankment, is the ‘wrong’ side of what flood defences do exist. In some ways it could be said to give a more accurate impression of how vulnerable London is. Were it not for the hard engineered flood defences many more roads would regularly look like this. The map at the bottom of the page is from the Environment Agency (click here for dynamic version). It shows these hard defences in pink and the areas at risk of flooding without defences.
The long term view, several hundred years, could easily see sea level rise of several meters. At which point cities on tidal estuaries like the Thames are unlikely to be viable. What should one do today, if one believes much of London to be uninhabitable in several hundred years time? How much should be invested to protect the city for the next hundred or two hundred years, if its loss four hundred years from now is inevitable? Of course these numbers are just educated guesses but the question is a serious one.
London flood map from the UK Environment Agency
The EA flood map makes me feel very secure, despite the fact that I live across the road (the dry side) from the point where these photos were taken. Even for my basement to flood would require inundation of much of the City of London and Canary Wharf – they have good reason and plenty of resource to prevent that happening! (or perhaps they will just build a big wall around their buildings and use the rest of us as sacrificial “flood plain”).
What should the city do? Apart from, maybe stop adding to their own problems by insisting on flying around the world, shipping unnecessary things to unnecessary places and generally being carbon-stupid? I think it was you who was talking about the areas in New Orleans which were flooded by Hurricane Camille becoming the poorer and thus more vulnerable areas by the time of Katrina – I imagine that is what might happen. Perhaps Fulham and Battersea will be the new “east end”, while the wealthy desert the less secure areas for higher ground. Gradually though – over the couple of hundred years you are talking about – not a sudden shift.
I don’t think the city will plan for this, it will just be a gradual evolution. It always has been the case that once-poor areas become “gentrified” and then abandoned again by the wealthy once another area becomes more fashionable. Rising tides will be only one factor among many which contribute to this changing landscape.
The Lincolnshire coast is probably more vulnerable than Putney. In some respects it is already an ‘east end’ with many thousands of people living in caravans – even more vulnerable than the thousands who live in bungalows. The Environment Agency estimates the probability of a major sea defence breach at around 1% in any year (0.5% for Boston). That’s now, before further sea level rise. EA policy is to maintain the current risk as sea level rises.
Tom Darden on Making It Right in New Orleans:
http://www.treehugger.com/files/2010/02/treehugger-radio-tom-darden-making-it-right-in-new-orleans.php
This area (and others nearby) are flooded quite frequently. Something to bear in mind is that river flow can add to the tide quite considerably, especially when Richmond Lock is open. There doesn’t need to be particularly bad sea weather to make this zone flood; a week of consistent heavy rain upstream can be enough.
A London that looks like Venice may be the future, perhaps a new name: “City of Water” or “The Floating City”.
Lived in this area for years, the river does this all the time! In fact there are clear signs that tell people to park at their own risk on this street. With in a few hrs the tide goes so far back one can walk on the shore line of the river thames. This part of the river is ‘controlled’ man made tides.Depending on rainfall sometimes streets like this will get some flooding. It’s not until you go as far as Teddington where the tides are more natural.Granted Climate change and water levels are important to be aware of. However, this is not Climate change this is typical Man made tides in Central London.
Yes Nic, I agree with all you say, this isn’t climate change and state in bold that this is normal. My point in this article is the long term, over several hundred years, impact of sea level rise on a city already located at sea level.