We all know the threat that coastal cities will likely be inundated by rising seas. Indeed in some parts of Australia, Local Councils are apparently declaring that some low lying residential areas are to be abandoned. Residents are, I’m told, even being forbidden from raising their houses higher or otherwise attempting to protect them. This is, in my opinion, crazy. It seems to be a way of trying to pretend that we should not act, or that everything will be ok.
Other people point out that certain cities, such as New Orleans, or even countries such as Holland, are already beneath sea level, and its all ok. Of course in New Orleans this was one reason why Katrina was so disastrous. However, when things, like being beneath sea level are normal, and have been normal for a long time, they can be generally be dealt with, no question. Levee and dyke walls already exist and perhaps it will be feasible to expand them to cope with the extra pressure of more water.
Some problems here stem from the nature of the cities themselves. Some cities are built on relatively porous rock, or even on sand (think of the Queensland Gold Coast) and, in that case, waters may flow under levy walls, and rise up to sea level. New sea walls are also likely to have to extend either for large distances inland or along the coast and change the coastal ecology and erosion patterns – although those will also be changed by climate change. Relatively close to the surface water tables could also be contaminated. It is complicated.
Other people can argue that the current rate of sea level rise is so slow that we have nothing to worry about at all. For example we can quote the Royal society, the “best estimates of the global-average rise over the last two decades centred on 3.2 mm per year (0.12 inches per year).” At this rate it would take over 600 years to get a rise of 2 metres. We could probably deal with this quite easily.
However, there are lots of problems with accurate prediction of such things as sea level rise.
The first is that the rate of rise is not going to be linear. The more land ice melts, the less radiation reflected into space and the more land ice will melt. The more greenhouse gases we keep emitting then the faster the melting will happen, and if we reach the tipping points at which methane starts rising from the deep ocean and the tundras, then it could start happening very rapidly.
People keep talking as if climate change and its problems expressed a nice gentle and smooth process, but it is not going to be that way. It is turbulent and chaotic. The climate system is what is known as “complex”, and turbulent change, once it is thrown out of equilibrium, is its nature. It will be hard to deal with, once things really start shifting, and they could shift rapidly.
That is why we need to act now while the situation is not too bad. That is why we keep being told that we have to reach greenhouse gas targets by 2030, and that it is better to come in even lower. If we don’t reach those targets then the probability of great turbulence is very high.
Anyone who tells you there is nothing to worry about, is assuming that they can predict a nice transition or control that transition. This position is extremely unlikely.
It is best to agitate for action to reduce greenhouse gas emissions and reduce the possibility of chaos, now.
Tags: Anthropocene, climate change, complexity, Disinformation
Climate, technology and chaos Blog 
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