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Climate Change Data Discussion

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St. John, New Brunswick. Looking at the graphs geographically - US ... Saint John, NB. Y = 2.0542x 2955.8. Eastport, Maine. Y = 2.0979x 2932.3. Bar Harbor, Maine ... – PowerPoint PPT presentation

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Title: Climate Change Data Discussion


1
Climate Change Data Discussion
  • Sea Level Change
  • October 2008
  • Prepared by C. Tilburg

2
Data Source
  • All data from Permanent Service for Mean Sea
    Level, data retrieved March 17, 2008 by C.
    Tilburg
  • http//www.pol.ac.uk/psmsl/
  • The PSMSL was established in 1933, and is the
    global data bank for long term sea level change
    information from tide gauges. The PSMSL collect
    data from several hundred gauges situated all
    over the globe.
  • Monthly and annual mean values are reduced to a
    common datum making use of the tide gauge datum
    history provided by the supplying authority.
  • The datum at each station is defined to be
    approximately 7000 mm below sea level (arbitrary
    choice made to avoid negative numbers.

3
Key Questions
  • How many sites does the subcommittee feel are the
    minimum required (currently have 8)?
  • For this indicator is there merit in staying
    with one data source?
  • What is the appropriate length of record
    (currently have 37 106 years)?
  • What is more appropriate for managers?
  • True sea level change
  • Sea level crustal rebound/subsidence
    oscillations in sea level
  • Any other important questions?

4
Boston, Mass.
5
Seavey Island, Maine
6
Portland, Maine
7
Bar Harbor, Maine
8
Eastport, Maine
9
Yarmouth, Nova Scotia
10
Halifax, Nova Scotia
11
St. John, New Brunswick
12
Looking at the graphs geographically - US
13
Looking at the graphs geographically - Canadian
14
Sea Level Change Detail
15
Peter Slovinskys Questions
  • Should we put the latest SL rise measurements
    (1.8 mm/yr) into a larger historical context by
    sharing a historic sea level trend?
  • http//www.state.me.us/doc/nrimc/mgs/explore/marin
    e/facts/sea-02.htm
  • Historically, relative sea level has varied
    dramatically over the past 13,000 years, mainly
    influenced by glaciation/deglaciation and
    subsequent crustal depression and isostatic
    rebound.
  • At the Portland gauge, the current rate over the
    last 100 years (since 1912) is the fastest
    measured SL rise rate over the past 3000 years.
  • This is significant because the majority of our
    modern day beaches and marshes formed when SL
    rise was at a rate of 1-1.2 mm/yr.
  • This is also significant because it matches the
    eustatic global ocean changes measured by the
    IPCC therefore, we are seeing little in the way
    of influence of rebound, subsidence, etc. at
    least at the Portland gauge.
  • The State of Maine adopted a 2 ft rise over the
    next 100 years into its Coastal Sand Dune Rules. 
    Is this number appropriate given the most recent
    studies of accelerated rates?
  • Should we just use NOAA tide data instead of
    PSMSL?  http//tidesandcurrents.noaa.gov/gmap3/
  • For management purposes, especially on the local
    and state levels, I think it is important to use
    relative sea level changes instead of global
    changes, as rates will vary from state-to-state,
    and region-to-region based on local subsidence,
    hydrocarbon removal, etc.
  • Should we also be discussing any of the IPCC
    model predictions at this point?
  • Should we also be discussing the role of melting
    of Greenland ice sheets or Antarctic melting?
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