The Thames Barrier has saved London – but is it time for TB2?

Posted on Posted in Chairman’s Blog

Its increasing deployment trend compares well with that of PAL’s correlation of extreme weather-related disasters and global warming – another evidence-based validation of PAL’s algorithm-based predictability.

My previous blog highlighted the escalating number of closures of the Thames Barrier in recent years, noting that they no longer guard solely against tide/storm surge: the Barrier now also protects London from upstream fluvial events caused by unprecedented volumes of rainwater increasingly being dumped on Britain’s capital as the weather changes.

To blame climate change rightly demands evidence, and in many ways the number of Barrier closures is an excellent metric. With 80 staff , annual operation costs of £6million and usage limited by maintenance and repair requirements, the Barrier is only deployed in dire need. Get it wrong and you have a flooded city, uproar and insurance costs or the accountants on your case.

Predict Ability Ltd (PAL) examined the evidence: Fig. 1 shows the trend in Barrier operations, with the tide/surge and fluvial events combined. A second series has been added: the ‘seasons with closures’ bars only occur in seasons (half years) where there have been one or more closures of the Barrier.

 

Thames Barrier operations showing seasons with closures and number of closures per season. Seasons with closures trends at 0.59% per year

Fig. 1 Thames Barrier operations showing seasons with closures and number of closures per season. Seasons with closures trends at 0.59% per year. Copyright Predict Ability Ltd (PAL).

Each plot has a linear trend line. The number of closures (blue line) is rising at 12.1% per year. The binary (0 or 1) ‘years with closures’ (red line) is rising at 0.59% per year.

The slope of the blue line reflects the dozens of closures required as a result of the UK’s exceptionally wet winter of 2014. Meteorologists generally agreed that a jet stream meandering across northern latitudes got ‘stuck’, causing intense winter cold and intense rainfall in the Northern Hemisphere. Yet to be agreed is how climate change causes such phenomena, but perhaps the warming arctic has a part to play?

This is where the ‘seasons with closures’ trend clarifies matters: its red line shows the increasing number of seasons in which the Barrier has been deployed, rather than the number of closures in any given season. Here the trend at 0.59% matches closely PAL’s predictions as to the influence of climate change on extreme weather-related disasters in general that has a trend of 0.50% per year.

Lying at the heart of Predict Ability Ltd’s PALgamma algorithm is a method for calculating the effects of climate change. Its exponential curve is currently rising at 0.5% per year. When everything else is accounted for, climate change is already causing 20% excess disasters as determined from Munich RE’s reports.

 

The correlation between normalised extreme weather-related disasters and the warming trend of 0.50% per year

Fig. 2 The correlation between normalised extreme weather-related disasters and the warming trend of 0.50% per year. Copyright Predict Ability Ltd (PAL).

Fig. 2 is from the book Predicting The Price Of Carbon by my colleague, Richard Clarke. Normalised extreme weather-related disasters are plotted as a blue line for the period 1980 to 2014 – the 35 years covered by Munich Re data. Also plotted, as a red line, is the Predict Ability Ltd (PAL) data generated by our climate attribution algorithm, PALca. It represents the impact of temperature anomaly (global warming) on climate change. In Fig. 2, the slope of the best-fit straight line is about 5.0% per decade, higher than the IPCC’s estimate of 3% and, crucially, close to the 5.9% trend shown in Fig. 1. In addition to a major US study I covered in a previous blog this study of Thames Barrier closures is also another independent evidence-based validation of PAL’s algorithm-based predictability.

So, is it time for TB2? If PAL’s model is right, then just 30 years from today the average number of closures per half-year season would be 9. Another ‘stuck jet stream’ season, however, might require 85 closures – so it is definitely time for London to plan ahead now.

In 2014, the late Science Writer and Journalist, Michael Hanlon wrote in The Daily Telegraph newspaper, “The Thames Barrier has saved London – but is it time for TB2?”

As Fig. 1 and Fig. 2 show, both independently and conclusively, Michael asked the right question – and yes, it is time for TB2.

 

Bruce Menzies, Chairman, Predict Ability Ltd (PAL)

© Copyright Predict Ability Ltd 2018. All rights reserved.

 

Image: The Thames Barrier (UK Environment Agency)

Bruce Menzies

Author: Bruce Menzies

Bruce Menzies is Chairman and co-founder of PAL. He founded Global Digital Systems Ltd that won the Queen’s Award For Enterprise 2011. Bruce is co-author of six books on geotechnics and geology, one of which won the British Geotechnical Association Prize 2002. He holds doctorates from the Universities of London and Auckland, and is a Fellow of the Institution of Civil Engineers.

The Thames Barrier has saved London – but is it time for TB2? was last modified: June 29th, 2018 by Bruce Menzies

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