At this point in my blog, I could try to explain to you the science behind climate change, and the ever-growing body of evidence demonstrating that the atmosphere is getting warmer and that this is almost certainly the result of human activity releasing astonishingly huge quantities of greenhouse gases. I could show you the 5th report from the Intergovernmental Panel on Climate Change (IPCC) published this year demonstrating yet again the consensus from scientists across the world about this problem.
But I won't, because you learned the basics of the greenhouse effect at school and people have an uncanny tendency to switch off as soon as anything is mentioned that relies upon them understanding any details about the workings of the troposphere. I am not a climate scientist, I'm a civil engineer. So instead, I will tell my own story of how the change in our climate is already affecting us in the UK and my daily work through storms, floods and landslides.
Storms
It was a dark and stormy night... again. In fact, I had to change my travel plans for Christmas and yesterday my sister almost didn't make it out of Scotland because the storms had caused widespread disruption to the transport network. While I have been enjoying Christmas with my family, many families have been flooded out or without power supplies. Boxing Day night was the fourth major storm we have had in the last 6 weeks with record high winds and storm surges affecting different parts of the country.
So as my colleagues work overtime yet again to clear the railways of fallen trees, trampolines and sheds which have blown away, get the power supplies up and running again and repair the landslides caused by the heavy rain over Christmas, I fall to wondering why so many storms this year? Why so violent? And why has this winter forgotten to be cold? We have barely had more than one frost a month in October, November and December this year.
Here is one part of the answer: in the summers of 2007, 2012 and 2013, the Arctic warmed to a level never seen before and there was less than half the normal amount of ice remaining by the end of the summer (based on average levels over the last 40 years). Climate modellers have demonstrated that low levels of sea ice results in more evaporation from the sea and a change in weather patterns for adjacent countries like Britain. It is therefore no coincidence that 2007 and 2012 were also warm and very, very wet for people in Britain and this year has been full of storms.
Floods
One of my first major projects was a flood alleviation scheme in Wakefield, which was badly damaged in the 2007 floods. I was very glad that we finished just in time for 2012, as my two completed flood storage dams were tested to their limit only a few days after we shut the penstock to allow them to start operating. We designed the dams so that they only let a certain amount of water flow through them and temporarily store any extra water to prevent flooding downstream. This provides capacity for floods up to 1% (1 in 100) chance of happening in any given year, but on their first operation they stored nearly the full capacity! Meanwhile, I moved to York in 2012 and watched the floodwaters come again and again, reaching 5.07m in September (the record figure is 5.40m, which happened in 2000).
The bottom line is, we cannot build flood defences fast enough to cope with the increasing flood risk, Part of the problem is due to where and how people build: we need to move away from building on flood plains and provide sustainable drainage to account for the difference in run-off you get from a house roof or paved surface compared to a field. But it is also due to changes in the intensity and frequency of rainfall events. Flood modelling has become much more difficult, since the probability of a high rainfall event is based on the last 100 years of data: because the weather has changed, this is no longer representative! For those who resist what the scientists say, please consider this: for more than a decade, civil engineers have had to design more and bigger flood defences across the country to adapt for climate change impacts and we still need to build more to cope with the massive costs of increasing flooding.
Landslides
And now for a spot of ground engineering (my specialism). Landslides are generally caused by the combination of water and gravity. The water both reduces the strength of the soil (especially clays) and lubricates any existing slip planes within the hillside which makes it easier for the soil to move downhill. As my boss has always said, “Gravity always wins in the end, but water definitely helps”. The British Geological Survey even publish a helpful graph showing the number of landslides occurring every month compared with the rainfall.
So the result of the wettest year on record (2012) was a corresponding record year for landslides triggered by the combination of saturated ground and intense rainfall events. This means my ground engineering team has been kept very busy ever since assessing and designing remedial solutions for landslides in the Yorkshire area, and I have spent most of this year visiting one location to monitor it until we can implement the remedial solution (which will require a long road closure).
In Scotland, communities have been severed again and again from vital transport links due to landslides, with over 5 occurring on the A83 within the last two years alone. On one occasion, people had to be rescued by helicopter because their cars were trapped between two landslides. Generally the debris can be removed from the road fairly quickly (within a few days) but the full remedial solution can take weeks of road closures to implement, which may require a very long diversion and corresponding disruption to local communities and transport links.
On the railway between Scunthorpe and Doncaster, another type of failure occurred. A colliery spoil heap was sat upon weak alluvium and as the groundwater level rose, the ground supporting the spoil heap weakened until it spectacularly failed in February 2013, pushing up the adjacent four-track railway line by several metres (see pictures here). The railway line was closed for months while the problem was resolved and all four tracks had to be relaid from scratch.
This was not just inconvenient for passengers suffering months of rail replacement buses, but also interrupted the main goods lines from Immingham docks to Doncaster. Ironically, one of the biggest problems was that most of the coal-fired power stations on the east side of Britain rely on coal delivered to Immingham and sent along that particular railway line, so a landslide caused the very real possibility of a blackout. A few months ago, I sat at dinner with a track engineer who was responsible for inspecting the track along the diversionary route, which had seen traffic increase from a few passenger trains a day to 75 fully loaded freight trains, which means a lot more track maintenance!
So climate change has already caused us significant disruption through storms, floods and landslides. As an engineer, I am already coping with the effects and trying to adapt our infrastructure to operate under the new conditions. This is why I am convinced we must take action both personally and collectively to prevent the continued damage to our atmosphere.
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