3 ways climate models can help improve our understanding of ground risk

5th March 2021

Ground risk is the life blood of our company. We love nothing more than coming across a sinkhole while out on a walk, or peering down excavations around our towns to look at the soil and geological conditions, and their interactions with infrastructure. Why then, with our focus (ok, fine, obsession) with the ground, are we spending so many months perfecting our climate models? Today, we will look at three reasons:

1) Climate models can help show WHERE ground issues are likely to occur

Most ground risks do not occur in isolation. Rather, it is the manner of the interactions between the ground, the weather and the built environment that leads to “problems”. For instance, for household subsidence, three “S” factors need to be in present.

  • Shallow foundations (construction conditions)
  • Shrinkable clay soils (ground conditions)
  • Sustained hot and dry weather (climatic conditions)

If we take away just one of those factors, clay related subsidence is very unlikely to occur. So, a lot of our research has been focussed on developing robust models to predict how the summers will change the drying patterns of the ground.

At the moment, subsidence is more common in the southern parts of the country. However, as the climate changes new parts of the UK will be exposed to these hotter and drier conditions. This means that places like the north-east, which are not currently known as subsidence hotspots, will be seeing more and more houses suffering subsidence in the coming years. This leads us on nicely to our second reason we need robust climate models…

2) Climate models can help show WHEN ground issues are likely to occur

In the UK, the summers will become hotter and drier, and the winters will be warmer and wetter. This is a consistent, repeating message from the climate models. However, there are a range of models which predict different futures, depending on how much, and how quickly we as a society adjust our behaviours. For instance, if over the next 10 years, the whole planet shifted to a mostly plant based diet, using primarily human-powered local transport and minimal air travel, the projected climate would look very different by 2050 than under the current level of greenhouse gas emissions.

As a result, we use four different climate models, based of 4 different greenhouse gas emission scenarios. This allows us to consider when between now and 2080 we are likely to see ground issues spreading across various parts of the country.

But if this sounds all very uncertain… it is. So, when looking at climate models, it is great that…

3) Climate models can help show HOW LIKELY ground issues are likely to occur

As well as looking at where and when ground hazards will impact on the built environment over the coming decades, because our climate models are based on many, many simulations of future weather conditions, we can estimate the likelihood of certain climatic conditions for different locations, at different times.

So for our models, at the most basic level, as well as the most likely estimate (50th percentile) we provide the range of conditions, for each decade, under four emission scenarios between the 10 percentile (unlikely to be wetter and cooler than) to the 90th percentile (unlikely to be hotter or dryer than).

This range of values allows a simple presentation of the uncertainty levels, and allows organisations to make plans according to their appetite for risk.

So now that we have seen that climate models can help us understand where, when and how likely ground risks are to occur, which of these aspects do you need give more attention in the coming months?

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Blog written by Dr Tim Farewell

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Tel: 0330 900 7500