When we see weather extremes such as the current Brisbane floods, it’s easy to associate such a dramatic event with Climate Change – after all sea surface temperatures off the east of Australia have been in excess of 26 °C – and that’s where all the water has come from. However, as the above picture from 1974 shows, floods are nothing new in Brisbane, and this level of flooding appears to be roughly a 1 in 50 year event. In other words this is part of the normal climate of the area -or at least there is no obvious evidence otherwise.
And so the question that occurs to me is this: Why did people build a city in a place where they knew there would be floods? Now I know that a dam was built to reduce the risk of flooding, and so presumably things would be worse now if the dam had not been built. But nonetheless the question remains – is it smart to build houses in a place that catastrophically floods once in 50 years? I think the answer is ‘No’.
Now I suspect almost the entire population of Brisbane would disagree with me. In the same way, the people of New Orleans decided after Katrina that the answer to the question ‘Is it smart to build a city 18 metres below sea level in a Hurricane belt?’ was ‘Yes’. Why do people make such decisions? Well the answer is because is the individuals involved have lost everything they owned – and if they moved on and abandoned their old homes, then they would become effectively destitute. So staying makes sense for each individual. But eventually, in places where the flooding risk is so severe, and the costs of avoidance – in terms of dams and levees – so great, we will just have to say collectively: let’s move on. Because it seems pretty likely that Brisbane will flood again, and so will New Orleans.
So the problems of living in a marginally sustainable place such as Brisbane and New Orleans are severe. And there the question we are coping with is one connected with the frequency of extreme events in a particular climate. Now suppose that people decide to stay and spend 10 billion pounds making the place safe for, say, 100 years. How many times and how frequently are people prepared to spend that amount of money before it become cheaper to move on – to move higher. If climate change is active, many coastal communities may find that 1 in 100 year events happen once every 30 years – and then the economic and personal choice becomes more evenly balanced. And it will be many tens of years before we can definitely conclude that the climate has changed. But that is the nature of the challenge we face.
Now these are difficult questions to answer for rich countries such as Australia or the USA. For a poor country, such as Bangladesh, there is just nowhere else for people to go and then the prospect of increased frequency of flooding isn’t just an economic question, but a matter of life and death.