Category Archives: Climate Change

Two Paris heatwaves two centuries apart

In July 1808 Paris wilted in a heatwave. The average maximum for the 13-day spell that began on the 10th was 31°C, higher than a similar spell last month that saw the all-time record for the French capital broken.

The temperature at the peak of last month’s hot spell reached 42.6°C, some 6.4°C higher than the peak of the 1808 spell but, as the graph below shows, maxima fell back more quickly than 1808.

paris heat line

The more ‘pointed’ nature of maximum temperature during the spell last month backs up findings of the changing jet stream;  the wriggly nature amplifying the heat.

Tmin

mean

The average mean and minimum temperature of both spells showed a difference of just 0.2°C.

Since Paris recorded its hottest day ever there have been just two days where the temperature has exceeded 30°C.

paris july 1808
The values for the 1808 spell were listed in Luke Howard’s Climate of London.

The heat in Paris in 1808, like in 2019, was also felt in London. Luke Howard noted the following in The Climate of London.

“Very hot from July 12th to 19th. On the 12th a thermometer in perfect shade in a window in St James’s Park was 81.5 degrees at 3pm, and on the 13th at the same hour, 94 degrees. On the same day four men and seven women were killed by sunstroke in various parts of the Midland counties, and numerous coach and other horses were also killed. On the 15th a very violent and destructive thunderstorm in Gloucestershire, Monmouthshire, and surrounding counties.”

* Values for 2019 were taken from the station Montsouris.
** Though there is no way of knowing how accurate the 1808 values were previous studies have found that historic temperatures can be as much as 3°F too high.

Advertisements

June 2019: record heat spike

June 2019 saw no high temperature records broken but a jump in anomaly, produced on the 29th by the 3rd hottest June day back to 1959, is higher than any I can find back to that year..

The only phenomena similar that I can find, albeit in the other direction, is the Beast from the East in March 2018 that sent temperatures plummeting.

The month finished a little above average though the final figure, like May and April, masked cool warm spells.

The mean temperature finished 16.9C that’s 0.8C above average, the coolest for 3 years.

Rainfall was 63mm, 123% of average, the wettest for 2 years. Sunshine was 158 hours, 88.7% of average, and dullest for 3 years.

A timelapse of the longest day can be found here.

To view full stats follow this link:http://1drv.ms/1kiTuzv

june 2019
‘Feels like’ maxima.
12.1
June 1981-2019 maximum anomalies
june anoms

 

The 12 month rolling rainfall total, thanks to a wetter than average month, has moved above 500mm again.

Summary for June 2019

Temperature (°C):
Mean (1 minute)  16.8
Mean (min+max)   16.9
Mean Minimum     12.1
Mean Maximum     21.7
Minimum          7.1 day 08
Maximum          33.6 day 29
Highest Minimum  18.0 day 24
Lowest Maximum   14.4 day 10
Air frosts       0
Rainfall (mm):
Total for month  63.3
Wettest day      18.7 day 10
High rain rate   20.1 day 09
Rain days        13
Dry days         17
Wind (mph):
Highest Gust     24.4 day 08
Average Speed    2.7
Wind Run         1932.6 miles
Gale days        0
Pressure (mb):
Maximum          1031.5 day 27
Minimum          998.4 day 07
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

 

 

 

 

 

 

 

East London’s highs and lows of the last 60 years

The chart below shows every maximum and minimum temperature recorded in this area since January 1st 1959, some 21,860 days!

The extremes range from -12.7C recorded on January 31st 1972 to 37.5C on August 10th 2003.

After peaking in 2003, summer maxima seems to be in decline. Winter minima, by comparison, has been increasing since 2012

maxmin

‘So much for global warming…’

Since notably cold weather struck at the end of February I’ve lost count of the number of times I’ve heard this phrase uttered by the public and some sections of the press.

Top 20 cold
Top 20 cold anomalies

The ‘Beast from the East’ (versions 1.0 and 2.0) really captured the imagination in an age where everything has to have a label slapped on it; any message that these cold spells are ‘weather’ and not ‘climate’ seems to get lost.

Both spells, indeed the general pattern of our late winter weather, were driven by the stratospheric sudden warming event that lead to a split polar vortex in February – leading to a very cold end to the month and a mean temperature anomaly of -2.5C, the greatest monthly anomaly since March 2013.

To put it into perspective, however, it was nothing like some of the anomalies that occurred in the early 19th century: January 1814, for example, saw a monthly anomaly of -8.2C and coincided with the last occasion a frost fair was held on the Thames. Januaries back then were generally very cold, the 1801-1831 average monthly mean was -3C, that’s 8C colder than the most recent 1981-2010 average!

So climate now is much warmer but that is not to say that anomalously cold months can’t happen. February 1986 saw an anomaly of -5.6C, the 13th= greatest cold anomaly in my local dataset going back to 1797.

top 20 warm
Top 20 warm anomalies

The cold December of 2010 recorded an anomaly of -4.2C, 76th= greatest cold anomaly, while anomalies of -4.1C recorded in January 1979 and March 2013 were 77th=.

With the warming climate it is no surprise that most warm months happened very recently. The balmy month of December 2015  saw a positive anomaly of 5.4C.

The ‘Beast from the East 2.0’ was caused by a narrow tongue of extremely cold air from Russia scoring a direct hit on the UK. The odds of this happening must have been low but it is an example of how, when the synoptics of the atmosphere line up perfectly, anything is possible.

And it is an example how even in a warming climate the UK can still be subject to anomalous cold and warmth at any time of the year.

As the author Mark Twain reportedly once said: “The climate is what you expect; the weather is what you get.”

gfs
The upper air anomaly of the ‘Beast from the East 2.0’. 
anom
This graphic shows positive and negative monthly anomalies since 1797 against a generally warming climate

Because the above graphic is crowded I created one of anomalies since 1970. The upward trend is the same.

1970

march 1st

June weather can be flaming horror show

The past week has produced the highest 24-hour rainfall total recorded in Wanstead since at least 1960. The multi-cell thunderstorm on Wednesday night saw 60.8mm fall, most of it in two hours, bringing flash floods to the surrounding area. The spectacular lightning and thunder that accompanied it was almost a side show such was the intensity of the rainfall.

rainradar
An image from the Home & Dry app revealed a succession of dark red echoes passing over our area. The heaviest rain seemed to run on a line from Battersea to Romford

I was unfortunate enough to be riding home right in the middle of the event: the entire length of the Mile End Road bore a resemblance to a shallow river, the heavy rainfall bouncing back off the Tarmac high enough to create what felt like a powerful drench shower.

The legacy of the downpours caused chaos in the morning and evening rush-hours. Many commuters were stranded at London terminals including Waterloo station because of flooded tracks, possibly robbing many of the chance of voting in the EU referendum. It will never be known if this would have had a bearing on the final result.

Many people think of June as a warm, summery month. The term Flaming June  is regarded in most peoples’ subconscious as a reference to past weather. That it is a actually the name of a painting is often missed. Looking back through our local history there has been many notable events of thunderstorms and prolonged rainfall. In 1903 a record-breaking 59-hour deluge left vast swaths of the borough inundated.

list
The offical UK weather station totals all recorded less than Wanstead

This weekend 200 years ago, during the Year Without a Summer, a powerful tornado, strong enough to carry away objects weighing 60lbs, tore through the Edgware Road area in west London. Luke Howard recorded the event in the Climate of London.

At two o’clock being a still sultry day a whirlwind passed over the nursery ground of Mr Henderson in the Edgware Road which lifted seven lights from the greenhouses and carried them to the height of the highest elm trees, each of the lights weighs 50 or 60lbs at least. At the same time two garden mats were carried to an immense height so that the eye could not distinguish them.

The following day “extremely heavy and prolonged rain from 9am (26th) to 9am on 27th gave 2.95 inches”. This total of over 52mm is notably high though not a record.

This weather was a continuation of what had been an awful May and June – cold with more than twice the average rainfall in June.

The weather then was not unlike what we have experienced this month. Indeed, a look at the weather throughout this year was similar as this graph shows.

compared

Though the mean temperature at times bears a close resemblance this year is no comparison to 1816: The mean then was running at 6.2C, over 3 degrees colder than today.
Mean pressure was also lower being 992.1mb; the 2016 mean 9am pressure is 1010.6mb.
Perhaps not surprisingly this year’s rainfall rainradaractually trumps 200 years ago; the running total for rainfall here is 390.1mm, higher than the 309.6mm recorded in 1816.

The dreary summer and frequent thunderstorms of 1816 inspired Mary Shelley to write Frankenstein. A summer vacation in Switzerland led her to spend much of the time indoors. She, along with Lord Byron and John William Polidori entertained each other with a contest to write the scariest story of all. The unseasonal conditions, along with this dare, led to the creation of Shelley’s Frankenstein: The Modern Prometheus— as well as Polidori’s novella The Vampyre and Byron’s long-form poem, The Darkness.

It will be interesting to see if this June’s weather, along with momentous political changes here and in Europe, produce more fine fiction from the this and the next generation of writers.

wind
Wind speed during the event from 2300 to 1000
temp
Temperature during the event from 2300 to 1000
pressure
Pressure during the event from 2300 to 1000
raintoday
Rainfall from 2300 to 1000
tipper
Rainfall rate from 2300 to 1000

 

Another development on Thames floodplain

A new suburb the “size of Windsor” is being planned for Barking Riverside, the site of the old Barking Power station, according to a report in the Financial Times.

barking riverside
The Barking Riverside site is sandwiched between two sewage works and a power station

Some 10,800 homes are being planned for the 179-hectare site by the housing association London & Quadrant in association with the Greater London Authority. The report states that £70m will be invested in extending the London Overground rail line to the site. But no mention is made on how much will be invested in flood defences.

Nor does it say that the site is sandwiched between sewage works on either side of the river and a power station and the Ford Motor works to the east.

It is part of the Mayor of London’s ambition for a City in the East that also makes no mention of how much money will be invested in flood defences to make these new estates safe.

This 200,000 home masterplan for East London should be music to the ears of anyone struggling to find a place to live in our overcrowded capital.

But unless planners are willing to spend billions on new flood defences it is possible that these new homes will be particularly at risk of flooding should rainfall levels increase with climate change.

The Environment Agency's Flood Plan map of the Thames illustrates Howard's comment that "the Thames was so full during this time that no tide was perceptible"
The Environment Agency’s Flood Plan map of the Thames illustrates Howard’s comment that “the Thames was so full during this time that no tide was perceptible”

Many of the developments mooted in London Mayor Boris Johnson’s plan for a City in the East are situated on flood plain, according to the Environment Agency.

On reading through the blueprint flood risk isn’t mentioned once.

A report in the Financial Times, citing the plan, says there is much more potential than previously thought to increase housebuilding in east London, the capital’s planning chief estimates. Sites earmarked include the Lea Valley and areas along the Thames beyond Canary Wharf.
‘Thames Riverside’, the term for an area along the north side of the Thames including Barking and Beckton, could host 27,000 homes, while areas on the opposite side of the river could hold 22,000, according to the report. There could be 52,000 more homes in Lea Valley, 30,000 on the Isle of Dogs and 15,000 in Woolwich.
Sir Edward Lister, deputy mayor for policy and planning, believes the capital’s authorities had learned from their experience with the Nine Elms regeneration area, where a statement of intent had galvanised developers.
“We just have to commit and then the developers can move in,” adding that there were “vast” amounts of underused post-industrial sites along the river in east London.
The housing plans also include commercial and industrial buildings, giving potential to create 280,000 jobs, as well as supporting infrastructure such as schools and hospitals. Transport improvements, such as Crossrail and a new London Overground line, would make the developments ‘desirable’. But costs would be dwarfed by any flood defence improvements.
Previously the Environment Agency has outlined a range of options for the future of the Thames Estuary flood defences. None are particularly cheap.

As a minimum, the EA estimates that the cost of maintaining the defences until 2035 will be around £1.5 billion, with an additional £1.8 billion needed to repair and upgrade the defences until 2050. Particular bits of marshland could also be set aside to store tide waters.

The River Lea close to where Luke Howard's laboratory stood by wanstead_meteo
The River Lea close to where Luke Howard’s laboratory stood

More ambitiously, the government could fund a new barrier in either Tilbury in Essex or Long Reach in Kent. Such a barrier would be designed to resist the highest surge tides identified by the Met Office’s analysis of how conditions will change this century. The EA estimates a new barrier could cost as much as £7 billion, though that figure could go up if conditions change significantly as the climate changes.

The Agency also say the existing barrier could be converted to include locks, which could open and close more flexibly and extend the life of the defences. The EA report says a decision on a new barrier will have to be made by 2050.

It may turn out that there’s a more pressing reason to spend. The EA says 50 is the maximum number of times the barrier should close each year, and beyond that, the barrier could start to fail.

How high is the likelihood of flooding in this part of London? A look back through history shows the geography of the Lea Valley has made the area prone to inundations for hundreds of years.

The Environment Agency's Flood Map for Planning shows the flood zone risk of the area. And endorses Howard's account that the river Lea was 'a mile wide' at its peak
The Environment Agency’s Flood Map for Planning shows the flood zone risk of the area. And endorses Howard’s account that the river Lea was ‘a mile wide’ at its peak

In January 1809 the lower River Lea burst its banks in several places following a deluge that dumped two inches of rain in the space of 24 hours. The rain abruptly ended a snowy cold spell that had begun over a month before in the middle of December. From Luke Howard’sreadings it is likely that up to half a metre of snow had fallen in the previous weeks in the upper parts of the surrounding countryside with only slight thawing. With the frozen ground unable to absorb any of the rapidly melting snow and rainfall the amount of water flowing downstream must have been immense. Howard takes up the story…

“The River Lea continued rising the whole of the 26th… The various channels by which it intersects this part of the country were united in one current above a mile in width which flowed with great impetuosity and did much damage.”

Howard, his chemical factory located on the banks of the river Lea close to what is now Bow flyover, wrote at length about the event, his account replacing the usual brief notes about daily weather in his book The Climate of London.

He talks of embanked pasture land being “filled to the depth of eight or nine feet” and people driven to their upper rooms relieved by boats plying under the windows.

“The Thames was so full during this time that no tide was perceptible.” It took until February 23rd for things to return to normal.

Wanstead Flats by Scott Whitehead
Wanstead Flats during the wet winter of 2013-14

Miraculously no lives were lost in the flood and cattle “by great exertions” were saved by being kept in their stalls. Howard, saying that the flood could have been far worse, believed a neap tide, strong westerly winds urging water down the Thames and mild weather helped avert a tragedy.

Howard’s statistics of the previous months show that the second half of 1808 were wetter than average – though not especially so. And nothing like the rainfall this area recorded during the winter of 2013/14. From December 1st until February 8th 1809 Howard recorded 130mm of rain, which is about 100mm less than what was recorded during 2013/14.

This fact alone shows just how much the nature of the river has changed in the last 200-odd years thanks to spending on flood defences.

Work to improve the defences was prompted 67 years ago when similar catastrophic flooding came with the thaw that ended the severe winter of 1947, one of the coldest winters in history and an episode remarkably similar to what Howard recorded in 1809.

The Lea Valley, along with many parts of the country, saw some of its worst flooding in a generation. The river burst its banks at several points bringing misery to surrounding communities. Valleys turned into lakes in 40 counties and East Anglia’s fens were a sandbagged inland sea. More than 100,000 properties were damaged and, then as now, heroic battles were fought by the military to keep water-pumping plants and power stations dry.

A marker of that flood, together with a history of flood defences, can be found here. There is also British Pathe footage of another flood between 1910 and 1919 here .

mill
Spillers Millennium Mill was repainted 25 years ago especially for the concert. It now provides the backdrop for the London Triathlon across from the ExCeL centre

The River Lea Flood Relief Channel, that flows between Ware, Herts, and Stratford, took almost three decades to complete. The channel incorporates existing watercourses, lakes and new channels. Since it was completed in 1976, there have been no major flood events in the Lea Valley, although there have been three occasions when the river system was full virtually to its capacity: in 1987, 1993 and 2000. Since its completion, the level of protection afforded by the structure has declined, so that in some areas it offers 2 per cent protection, and in some, only 5 per cent protection. The EA published a strategic environmental assessment in 2008, which looked at ways to maintain the flood defences in the Lea Valley.

In summing up its ambitions for a new development the Greater London Authority says it is trying to “overturn the historic perception of the east being seen as apart from London, rather than as a part of London”.

Jim Ward, a director of research at property consultancy Savills, said the challenge was “building something that makes people want to live and work there”, he said. “You need to build more than homes, you need to build a place.”

Boris’s record of late has not been good: an estuary airport to replace Heathrow has been dismissed as pie in the sky while his promise for a 24-hour Tube was made without first consulting unions that it was possible.

London’s safety from flooding is an altogether different proposition, both for old and new developments. Boris really needs to get London’s flood defences right before any brick is laid on these desperately-needed new developments.

Greenwich Peninsula awash with development

The race to build more riverside property on London’s floodplain has received another boost after a big development on the Greenwich Peninsula was given the green light.

The Environment Agency's Flood Plan map of the Thames illustrates Howard's comment that "the Thames was so full during this time that no tide was perceptible"
The Environment Agency’s Flood Plan map of the Thames

The Financial Times reported on Friday that Boris Johnson has given final approval to an £8.4bn, 12,700-home development that would transform this area of south-east London into a “high-rise urban village complete with film studio”.

Knight Dragon have already begun construction on the project, a 150-acre scheme approved 10 years ago in a more modest form but revived and expanded after the financial crisis.

The report mentions that local residents are concerned the scheme will place unbearable strain on the area’s transport links and that the size and density is out of keeping with Greenwich’s World Heritage Site of 17th to 19th-century buildings close by.

What is not mentioned is flood risk – a factor that, considering climate models, is deemed too minuscule to worry about. The proposed development satisfies this risk criteria – a report on the ‘Strategic Flood Risk Assessment’, drawn up in October 2011, mentions:

“Tidal flood risk is extensive, but at present Greenwich is fully defended against the 0.1% annual probability extreme tide level with climate change to 2107. A breach in the defences, although a low probability of occurrence, would have a high consequence, causing significant flooding of the Thamesmead, New Charlton and Greenwich Peninsula areas of the Borough.”

But is it wise to build on historic floodplain? Surely we should be looking elsewhere in London for safer sites for projects that will help ease the housing crisis.

The website floodlondon.com shares concern that developments such as these are at severe risk from a tidal surge when the Thames Flood Barrier nears the end of its working life in the middle of this century.

“Perched on the very tip of the Greenwich Peninsula, the O2 Arena finds itself ideally located on a nice sharp bend in the river where it is likely to take the full brunt of the surge as it careers into the bank, much like a racing car taking a corner too fast. The North Greenwich tube station just across the road will prove to be a great asset at this point as it funnels the water into the Jubilee Line.”

Before the Thames Barrier was built this part of the river has seen some catastrophic flooding.

thames flood november 18 1875
The 1875 flood as reported in the Morning Post
In November 1875, a year that was only slightly wetter than normal, a record high tide of 8.9m was recorded at Blackwall. The figure is 1.36m (4ft 6in) higher than the greatest high tide at North Woolwich (Silvertown) this year, according to tide tables drawn up by the Port of London Authority (7.54m on March 20th).
The flood brought chaos throughout London – with this part of the river particularly badly hit. Much of the Isle of Dogs was inundated, North Woolwich Gardens were under 3ft (1m) of water while the water caused explosions at the Royal Arsenal. Elsewhere in the capital Eton College was ‘completely surrounded by water’. A correspondent for the Press Association said the damage caused on the banks of the Thames was estimated to cost £1m sterling – just over £103m at today’s prices.
tues 16 nov
The Sunderland Daily Echo & Shipping Gazette on Tuesday, November 16, 1875 reported a depth of water at East India Docks of 29ft 2in. Damage was estimated to be £1m sterling – just over £103m at today’s prices.

Since the flood of 1953 measures, including the Thames Barrier, were put in place to stop this flooding. The Environment Agency has outlined a range of options for the future of the Thames Estuary flood defences. None are particularly cheap. As a minimum, the EA estimates that the cost of maintaining the defences until 2035 will be around £1.5 billion, with an additional £1.8 billion needed to repair and upgrade the defences until 2050. Particular bits of marshland could also be set aside to store tide waters.

The EA estimates a new barrier could cost as much as £7 billion, though that figure could go up if conditions change significantly as the climate changes.

Greenwich Peninsula and another project, City in the East, which was announced last month will need proper flood protection and planning. I wonder if planners are as willing to invest in these defences as they are at making a tidy buck developing these riverside schemes. And do our politicians have the appetite to drive the legislation through?

The problem is that if the climate change does bring greater rainfall and an unprecedented sea-level rise it is the people living in these properties that will be faced with the problem of ever-increasing costs to fight off the risk of inundation.

 

Will potent El Niño bring cold winter?

Much of the UK media has been very persistent in the past few months in saying that large positive anomaly El Niño years herald cold winters – basing their assumption on one year: 2009/10.coldandwarmepisodesbyseason

Whilst that winter was very cold, among the top 10 coldest of the last 70 years in this area, another El Niño year, 1997/98 – the strongest in recent history – brought London its third-warmest winter in a record going back to 1797.

When I had a look at ENSO data going back to 1950 a few months ago I found it impossible to find a definitive teleconnection between El Niño and winters in north-west Europe. However, now that we are midway through November, and with a fair impression of how the monthly mean will finish, I had another look.

NOAA data shows that the most similar El Niño years to this are: 1957, 1965, 1972, 1982, 1997, 2002. Taking in to account only mean temperature shows that November values have increased.

new el nino

What does this mean for this winter? It is still impossible to tell and is just another variable to consider when the time comes to predict winter.

CET v Greenwich values since 1850

The climate of London can vary greatly to figures revealed in the Central England Temperature series. Because this dataset covers an area of the UK enclosed by Lancashire, London and Bristol the resulting monthly mean temperature can often be quite a bit lower than what is experienced in the capital.

Though these anomalies are smoothed in the monthly series that stretches back to 1659 notable daily extremes that happen nationwide tend to get lost. One example was earlier this month when the UK’s November maximum temperature record was broken. Trawsgoed in Wales reached 22.4C on the afternoon of the 1st whereas a largely foggy east London recorded just 11.5C.

Comparing CET with data from Greenwich back to 1850 reveals a gradual decoupling between the two series, the warmth of London’s urban heat island effect an ever-growing influence.

CETvGreenwich

The 1851-1880 30-year average means show that Greenwich was 0.6C warmer than the CET series. By 1981-2010 this gap had widened to 1.2C – indeed the London series is today 1.4C warmer than it was in 1851-80 whereas CET has warmed by only 0.6C.

Delving further into the data reveals an increase in the number of times that the 30-year average mean is being breached by at least 1.1C. The period 1961-90 was the warmest in both cases with the mean being breached by 1.1C or more on four occasions in the case of CET and five in London. It is interesting to note, however, that the largest anomaly in the CET series is 1.3C in 1921, greater, albeit by only 0.1C, than the warm years of 1990 and 1999.

The largest anomaly in London, 1.6C, was set in 2011, 0.1C higher than 1999, 1997 and 1989.years exceeding relevant 30-year average annual temperature by 1.1C

The graph below shows the number of occasions that the 30-year average has been exceeded in each period by 1.1C or more. With 1961-90 being so warm it appears that CET warming has slowed though it should be borne in mind that we have another five years before the 1991-20 series can be released.

numberof years that exceeded 30-year average annual mean CET by 1.1C

With reference to the London graph below showing the number of occasions that the 30-year average has been exceeded in each period by 1.1C or more merely confirms that the level of the anomalies have increased but, as already mentioned, there are probably far more outside influences affecting the outcome such as UHI, population growth, further industrialisation etc.

The accelerated warming is a worry in terms of how London would adapt should summer temperatures greatly increase, though, of course, it remains to be seen if the anomalies will advance even further from current levels.

Global temperatures are on the rise though our part of the globe may not be as adversely affected as elsewhere.Size of margin when years exceeded 30-year average annual mean temp by at least 1.1C at Greenwich* The CET dataset is the longest instrumental record of temperature in the world. The mean, minimum and maximum datasets are updated monthly, with data for a month usually available by the 3rd of the next month. A provisional CET value for the current month is calculated on a daily basis. The mean daily data series begins in 1772 and the mean monthly data in 1659. Mean maximum and minimum daily and monthly data are also available, beginning in 1878.

For more information on CET follow this link.

Flood risk sandbags City in the East plan

Plans to build 200,000 homes in East London over the next 20 years should be music to the ears of anyone struggling to find a place to live in our overcrowded capital.

But unless planners are willing to spend billions on new flood defences it is possible that these new homes will be particularly at risk of flooding should rainfall levels increase with climate change.

The Environment Agency's Flood Plan map of the Thames illustrates Howard's comment that
The Environment Agency’s Flood Plan map of the Thames illustrates how much of the land that is designated for development is at risk of flooding

Many of the developments mooted in London Mayor Boris Johnson’s plan for a City in the East are situated on flood plain, according to the Environment Agency.

On reading through the blueprint flood risk isn’t mentioned once.

A report in the Financial Times, citing the new plan, says there is much more potential than previously thought to increase housebuilding in east London, the capital’s planning chief estimates. Sites earmarked include the Lea Valley and areas along the Thames beyond Canary Wharf.
‘Thames Riverside’, the term for an area along the north side of the Thames including Barking and Beckton, could host 27,000 homes, while areas on the opposite side of the river could hold 22,000, according to the report. There could be 52,000 more homes in Lea Valley, 30,000 on the Isle of Dogs and 15,000 in Woolwich.
Sir Edward Lister, deputy mayor for policy and planning, believes the capital’s authorities had learned from their experience with the Nine Elms regeneration area, where a statement of intent had galvanised developers.
“We just have to commit and then the developers can move in,” adding that there were “vast” amounts of underused post-industrial sites along the river in east London.
The housing plans also include commercial and industrial buildings, giving potential to create 280,000 jobs, as well as supporting infrastructure such as schools and hospitals. Transport improvements, such as Crossrail and a new London Overground line, would make the developments ‘desirable’. But costs would be dwarfed by any flood defence improvements.
Previously the Environment Agency has outlined a range of options for the future of the Thames Estuary flood defences. None are particularly cheap.

As a minimum, the EA estimates that the cost of maintaining the defences until 2035 will be around £1.5 billion, with an additional £1.8 billion needed to repair and upgrade the defences until 2050. Particular bits of marshland could also be set aside to store tide waters.

The River Lea close to where Luke Howard's laboratory stood by wanstead_meteo
The River Lea close to where Luke Howard’s laboratory stood. Since it was completed in 1976, there have been no major flood events in the Lea Valley, although there have been three occasions when the river system was full virtually to its capacity: in 1987, 1993 and 2000.

More ambitiously, the government could fund a new barrier in either Tilbury in Essex or Long Reach in Kent. Such a barrier would be designed to resist the highest surge tides identified by the Met Office’s analysis of how conditions will change this century. The EA estimates a new barrier could cost as much as £7 billion, though that figure could go up if conditions change significantly as the climate changes.

The Agency also say the existing barrier could be converted to include locks, which could open and close more flexibly and extend the life of the defences. The EA report says a decision on a new barrier will have to be made by 2050.

It may turn out that there’s a more pressing reason to spend. The EA says 50 is the maximum number of times the barrier should close each year, and beyond that, the barrier could start to fail.

How high is the likelihood of flooding in this part of London? A look back through history shows the geography of the Lea Valley has made the area prone to inundations for hundreds of years.

The Environment Agency's Flood Map for Planning shows the flood zone risk of the area. And endorses Howard's account that the river Lea was 'a mile wide' at its peak
The Environment Agency’s Flood Map for Planning shows the flood zone risk of the area. And endorses Howard’s account that the river Lea was ‘a mile wide’ at its peak

In January 1809 the lower River Lea burst its banks in several places following a deluge that dumped two inches of rain in the space of 24 hours. The rain abruptly ended a snowy cold spell that had begun over a month before in the middle of December. From Luke Howard’s readings it is likely that up to half a metre of snow had fallen in the previous weeks in the upper parts of the surrounding countryside with only slight thawing. With the frozen ground unable to absorb any of the rapidly melting snow and rainfall the amount of water flowing downstream must have been immense. Howard takes up the story…

“The River Lea continued rising the whole of the 26th… The various channels by which it intersects this part of the country were united in one current above a mile in width which flowed with great impetuosity and did much damage.”

Howard, his chemical factory located on the banks of the river Lea close to what is now Bow flyover, wrote at length about the event, his account replacing the usual brief notes about daily weather in his book The Climate of London.

He talks of embanked pasture land being “filled to the depth of eight or nine feet” and people driven to their upper rooms relieved by boats plying under the windows.

“The Thames was so full during this time that no tide was perceptible.” It took until February 23rd for things to return to normal.

Wanstead Flats by Scott Whitehead
Wanstead Flats: another area of east London that is traditionally flood plain

Miraculously no lives were lost in the flood and cattle “by great exertions” were saved by being kept in their stalls. Howard, saying that the flood could have been far worse, believed a neap tide, strong westerly winds urging water down the Thames and mild weather helped avert a tragedy.

Howard’s statistics of the previous months show that the second half of 1808 were wetter than average – though not especially so. And nothing like the rainfall this area recorded during the winter of 2013/14. From December 1st until February 8th 1809 Howard recorded 130mm of rain, which is about 100mm less than what was recorded during 2013/14.

This fact alone shows just how much the nature of the river has changed in the last 200-odd years thanks to spending on flood defences.

Work to improve the defences was prompted 67 years ago when similar catastrophic flooding came with the thaw that ended the severe winter of 1947, one of the coldest winters in history and an episode remarkably similar to what Howard recorded in 1809.

The Lea Valley, along with many parts of the country, saw some of its worst flooding in a generation. The river burst its banks at several points bringing misery to surrounding communities. Valleys turned into lakes in 40 counties and East Anglia’s fens were a sandbagged inland sea. More than 100,000 properties were damaged and, then as now, heroic battles were fought by the military to keep water-pumping plants and power stations dry.

A marker of that flood, together with a history of flood defences, can be found here. There is also British Pathe footage of another flood between 1910 and 1919 here .

Spillers Millennium Mill was repainted 25 years ago especially for the concert. It now provides the backdrop for the London Triathlon across from the ExCeL centre
The iconic Spillers’ Millennium Mills building has been redeveloped

The River Lea Flood Relief Channel, that flows between Ware, Herts, and Stratford, took almost three decades to complete. The channel incorporates existing watercourses, lakes and new channels. Since it was completed in 1976, there have been no major flood events in the Lea Valley, although there have been three occasions when the river system was full virtually to its capacity: in 1987, 1993 and 2000. Since its completion, the level of protection afforded by the structure has declined, so that in some areas it offers 2 per cent protection, and in some, only 5 per cent protection. The EA published a strategic environmental assessment in 2008, which looked at ways to maintain the flood defences in the Lea Valley.

In summing up its ambitions for a new development the Greater London Authority says it is trying to “overturn the historic perception of the east being seen as apart from London, rather than as a part of London”.

Jim Ward, a director of research at property consultancy Savills, said the challenge was “building something that makes people want to live and work there”, he said. “You need to build more than homes, you need to build a place.”

Boris’s record of late has not been good: an estuary airport to replace Heathrow has been dismissed as pie in the sky while his promise for a 24-hour Tube was made without first consulting unions that it was possible.

London’s safety from flooding is an altogether different proposition, both for old and new developments. Boris really needs to get London’s flood defences right before any brick is laid on these desperately-needed new developments.