Climate change, should we be concerned?

Speaking to an audience at the University of Greenwich in Chatham, Dr Andrew Haggart, a senior lecturer there recently posed the question as the title of a talk for the benefit of the local public.

He began by analysing climate change over the last 5 million years, and at first seemed fairly reassuring, predicting modest average changes: 15 per cent more rainfall locally in winter by the end of the century, 20 per cent less in summer, a 3 deg C rise in temperature and a 0.4m rise in sea level, but he then pointed out that it is harder to predict occasional events that could cause serious trouble. Since global CO2 levels have not, during the last 5 million years risen above 300 ppm, but are now at 385 ppm, we do not quite know what is going to happen, but should be mindful of past unpredicted events such as London being flooded in 1928, or the Canvey Island floods in 1953, and that while melting of the Greenland ice pack or the West Antarctic ice sheet would raise sea level by 7m, melting of both would raise sea level by 13m, and melting of all the ice sheets would cause a rise of 84m. Furthermore, whereas our remote ancestors migrated to seek more congenial weather when climate changed, this is no longer possible in the present more crowded world. And then as somebody brought up afterwards, there remains the problem of factoring in the effects of changes in water vapour content of the atmosphere into the models, which has a bigger greenhouse gas effect than CO2, and is produced both by sea evaporation and by aircraft.
Haggart’s advice to engineers was that they should, “Look to the most recent data and think outside the box, IPCC [Intergovernmental Panel on Climate Change] data tends to be conservative. It might be worth considering things that might happen and preparing for them”.

Tom Shelley

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