Evidence from: 30th October lectures entitled Is climate change science a barrier to flood management decision making? by Jon Wicks and What is the risk of drought in the Thames basin? by Jim Hall Both speakers had used climate change projections to estimate the effect on water flow. Both had been intensely aware of the political interest in their work. Speaker Jon advised that modelling was useful when it considered the probability of stepping over a critical threshold. First you must know what is the critical threshold e.g. a certain depth of flood water, and this is essentially a political decision. He added that modellers tend to focus on the things they can actually model and to underplay by their absence, the things they cannot model. For example, an administrative decision might increase the population in a low lying area thus approaching a loss of life threshold even in the absence of climate change. He presented an estimate that by 2050 the damage bill in Shanghai would increa