Climate change – flooding issues
54. CPRE finds Policy CC/FM: Flooding and integrated water management to be totally inadequate in the face
of the increasing flood risks arising in the county, the greatest of which is the likely loss of a high
percentage of the Fens to flooding within decades, as referred to above.
55. The river Great Ouse is tidal up to Brownshill Staunch between Earith and St Ives. This means that areas
such as Cottenham Lode, which extends to the A14 and the edge of Cambridge, are at future high risk of
tidal flooding as well as the fluvial flooding experienced in winter 2020/21 in places such as Cottenham, St
Ives and St Neots. There is also increasingly high risk of flash flooding in these low-lying areas due to the
increased intensity of rainfall arising from climate change. Such flooding was experienced in several areas
of the county, including Peterborough, during 2021.
56. The inexorable and increased rate of sea level rise means that the Fens will initially be subject to occasional
and then annual flooding. The annual flood risk will be increased by the additional volume of run-off from
development coming downstream. Eventually, the tidal inflow will cause permanent flooding and large
areas of the Fens will be returned to saltmarsh. However, even the first stage of annual flooding will have a
significant negative effect on agriculture and national food supply. It was found after the 1947 and 1953
floods that crop yields were reduced for seven years due to the presence of a nematode in seawater.
57. To illustrate this situation numerically, the Environment Agency has been measuring sea level (AOD) in the
Wash for many years. It was rising at a rate of 3 mm per year. In 2019 it was agreed that measurements by
the Environment Agency and by IPCC indicated that the annual rate of sea level rise had increased to 3.3
mm per year. The IPCC2014 report predicted global sea level rise of 1 metre by 2100. The IPCC2019 report
predicted sea level rise of 1.1 metres by 2100. In 2021, IPCC increased its estimate again to 2.4 metres by
2100. Climate Central estimates sea level rise of 4.7 metre by 2100 if global temperatures rise by 2°C.
Worryingly, in 2021 both the IPCC and the COP26 leadership have confirmed that the world can expect a
2.4°C global temperature rise.
58. Evidence shows that any increase in artificial surfaces, such as buildings and roads, leads to a decrease in
water in the environment. Development also leads to a decrease in the amount of land that can absorb
rainwater and recharge water bodies. According to the Royal Horticultural Society, 70% of ponds have been
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lost from the UK countryside since 1970. The River Cam has lost on average half its flow. In 2019, the River
Granta dried up completely. Freshwater biodiversity populations have declined by 84%.
59. By continuing to build on the scale planned, Cambridgeshire is sowing the seeds of its own destruction.
Firstly, it is creating avoidable carbon emissions which will contribute to global temperature rise. Secondly,
that temperature rise will cause large parts of the county to flood permanently. Thirdly, the additional runoff from development will increase the risk of flooding and bring forward the date of permanent flooding of
large parts of the county. This issue must be taken far more seriously than the token gesture of Policy
CC/FM