London adapts to the changing nature of 'extreme weather'

Environmental experts have urged local authorities across the country to follow the Greater London Authority's lead and develop their preparedness for extreme weather conditions as the UK's temperatures continue to rise faster than the global average.

Speaking at a London Assembly meeting on 'severe weather', Professor Martin Parry of Imperial College London said: "Two major challenges for all local authorities going forward will be how to plan for heatwaves and how to plan for extreme rainfall.

"London is ahead of the curve on awareness of extreme weather but it only takes a very small increase in the mean temperatures to have a major impact on responses and to disrupt daily life and impose costs on the economy.

"Authorities have to be ready in advance for incidents like flooding. Unlike incremental impacts such as droughts, the impact of excessive rainfall can be dramatic and, as shown this winter, if provisions aren't in fully place in advance the results can be drastic.

"But any changes need to be made based on accurate predictions, as multi-million pound projects like flood barriers can't be entered into lightly. So we need to make conscious decisions about what the extreme weathers of the future are and prepare for that."

Further reading: Extreme weathers have extreme impact on ART, PHE scientist says

Prof Parry went on to outline how the number of extreme rainfall events in the UK has increased from 1 in 30 per season to 1 in 6, leading Assembly member and LFEPA chair James Cleverly to query what now qualifies as "extreme weather".

The Environment Agency's Simon Hughes suggested that while the changes would not be obviously visible, around a 2o change per year until 2050, the best strategy was to plan in advance for 'extremes' becoming more commonplace and then adapt strategy as meteorological models become clearer over time.

Sleepwalk into major ecological & social problems
In recent years there has been a number of episodes of severe weather, on top of the recent floods with Met Office Climate Scientist Dr Matt Huddleston higlighting to the Assembly instances of wind storms, tidal surges, exceptional heat, dry winters and ice storms all causing differing forms of disruption.

Dr Huddleston said that while data is more certain on increases in rainfall, authorities shouldn't neglect other areas where the data is less clear such as with storms.

This fits well with the existing GLA approach outlined by Policy & Programmes Manager Alex Nickson who said that "the recent impact of heavy rainfall on sewage drain in certain areas of London has shown how we can sleepwalk in to major ecological and social problems without accurate modelling".

Nickson described the pathways approach being used to model all projected weather futures and generate resilience options which can be adopted with differing degrees of urgency depending on changing meteorolical forecasts.

This is exemplified by TM49 and TM52, the GLA's measure of the limits of thermal comfort, which calculates the conditions needed to create the optimum inside temperature at a specific outside temperate. 

Potential heat stressing impact on buildings
Prof Parry called for a similar measure to be written into building codes, which he believes should also factor in passive cooling.

"London, and all UK cities, need to have weather condition designed more into building regulations. The potential heat stressing impact of buildings in the area is huge, with up to 60% affected by high heat," added Prof Parry.

The impact is especially great in light of London's position of having the highest socio-spatial heat vulnerability in the UK. As such, Dr Huddleston says it is important to prioritise expenditure in services to tackle the problem now. 

Prof Parry agreed, concluding that based on 30 year-trends there could be millions saved if policy makers engaged with scientists now rather than having to rely on retro-fitting in the future. 

For more information visit the London Assembly Environment Committee's webpage at www.london.gov.uk/moderngov/mgCommitteeDetails.aspx?ID=305