London scoping - ukcip

Issue Main Points
Water Resources
Health
Final Report
200
Climate change could reduce the standard of river flood protection through rising sea
levels, rising groundwater and/or increased storm magnitudes. Beyond 2050 extreme
precipitation events of 30 and 60 day duration could increase in magnitude. By the 2080s
the 60 day precipitation event that occurs on average 1 in 10 years increases in magnitude
by 10%, whereas the 1 in 20 year event increases in magnitude by 16%. This could bring
with it increased risk of disruption and damage to underground infrastructure e.g. London
Underground and power and telecommunication lines from flooding. Any increased
flooding such as flash flooding due to heavy rainfall events would also affect above ground
transport systems. For instance, it has been estimated that disruption to rail services
caused by a flooded rail line affecting a London bound train in December 2000 cost more
than £1 million.
Increased water demand. Domestic water use could increase as a result of more hot
Summers leading to increased garden watering and personal washing. The Environment
Agency estimates that outdoor water use will increase public water supply demand in the
Thames Region by approximately 50 million litres a day due to climate change.
Reduction in annual rainfall due to climate change could affect the availability of water for
London. It has been estimated that there could be a decrease in average soil moisture
both annually and in the Summer in the South East. Drier soils imply more clay shrinkage,
induced subsidence and mains leakage. Drier soils will require more precipitation to
induce groundwater recharge and surface runoff. Therefore the length of recharge season
could decline by 8 days in the 2050s and 14 days by the 2080s. The scale of the
intensification planned for London (700,000 population growth in the next 15 years) could
exacerbate this problem in the short term.
Increased winter rainfall may result in the swelling of clays
Water resources could also be affected by a reduction in water quality due to wash-off
being carried down to combined sewer overflows (CSOs) and low summer flows reducing
the volume of water for dilution of treated effluent in receiving water courses.
Changes in rainfall patterns might result in abstraction licences being granted on a shorter
timescale to allow flexibility in planning for the availability of water resources.
Increased extreme temperatures could lead to an increased mortality related to heat
stress. It has been estimated that the summer heat waves in 1976 and 1995 were
associated with a 15% increase in mortality in Greater London.
Reduction in winter cold spell related mortality e.g. hypothermia. A recent Department of
Health Report has estimated that, by the 2050s, up to 20,000 fewer deaths might occur in
the UK as a whole as a consequence of climate change.
Increased pollution episodes. It has been estimated that a 1°C rise in Summer air
temperatures is associated with a 14% increase in surface ozone concentrations in
London. There could be an average increase in the frequency of pollution episodes of
over 4 days a Summer by the 2080s due to increased temperature inversions. This could
have impacts on the health of susceptible people.
Increased temperatures could increase opportunities for crime as windows and doors are
left open longer.
Higher temperatures could increase the number of road accidents due to driver drowsiness
and increased numbers of people cycling and walking.
Higher temperatures could mean that rubbish put out for collection may decay quicker,
producing unpleasant odours.