2 thoughts on “Biting the Breeze

  1. Christine

    The Thames Barrier (1974-84) was designed for sea level rises until 2030.
    [ http://encyclopedia.kids.net.au/page/th/Thames_Barrier ]

    “London is vulnerable to flooding. The threat has increased over time due to the slow but continuous rise in high water level over the centuries (75 cm / 100 years) and the slow ’tilting’ of Britain (up in the north and down in the south). This general rise in potential water levels combined with the tidal conditions of the Thames and with particularly severe weather conditions can create serious flood conditions – surge tides. After 300 people died in flooding in 1953 the issue gained new prominence.”

    This movement of the land relative to the sea is due to post-glacial rebound. Some land movements occur because of isostatic adjustment of the mantle to the melting of ice sheets at the end of the last ice age. The weight of the ice sheet depresses the underlying land, and when the ice melts away the land slowly rebounds. [ http://en.wikipedia.org/wiki/Sea_level ]

    In considering how London might adapt to climate change it would be important to know whether climate change predictions were part of the original calculations for the design of the Thames Barrier.[ http://www.guardian.co.uk/environment/2009/feb/13/climate-change ] If human induced changes were factored into the design, there should be 30+ years of predictive design data to test against factual occurrences.

    A similar Continental tilt (correction) is occurring in the US due to the melting of the ice sheet from the last ice age in Northern America. NY is rising while the West coast is sinking.

    “…outside the former ice margin, the land sinks relative to the sea. This is the case along the east coast of the United States, where ancient beaches are found submerged below present day sea level and Florida is expected to be submerged in the future[3]. GPS data in North America also confirms that land uplift becomes subsidence outside the former ice margin [2].”
    [ http://en.wikipedia.org/wiki/Post-glacial_rebound ]

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