CLIMATE CHANGE: Sea Levels & Coastal Development

Sea Level Rise: Ignoring the past, ignoring the present, ignoring the future

It seems folks really don’t believe sea levels are rising or aren’t aware that history shows our coastal areas are prone to massive and destructive storms that have virtually wiped out coastal communities and infrastructure and destroyed thousands of vessels.

As a consequence, it becomes a mystery why governments and businesses continue to invest in multi-million dollar civic buildings on a coastal flood plain instead of beginning the process of moving away from the threatened waterfront.

More ominous, the powers-that-be have resurrected an aged nuclear power plant at point Lepreau and continue to add nuclear waste to an expanded above ground waste storage area … all within the reach of the perfect storm should or when it occurs. Quite apart from ongoing problems and current emissions into the Bay of Fundy, the events at Fukushima, Japan clearly demonstrate the massive impacts that are occurring in the Pacific Ocean. A similar accident here would have a comparable impact on the Bay of Fundy, Gulf of Maine and adjacent areas in the North Atlantic.

Will our tides rise significantly?

The simple answer is “yes”. The tough question is “ much?”. NASA and other organizations have been studying this now for many years and in recent years most researchers have been astounded by the acceleration of the rise and the increase in projected height.  “With future warming, we may lock ourselves into multiple-meter sea level rise” over the coming centuries, says Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re talking about 6 meters—18 feet—and higher of sea level rise…  We just don’t know.”  (NatGeo News)

So what will 18 feet mean for our coastal communities …. some considerable loss and dislocation is coming for certain. At Point Lepreau Nuclear Power Plant the impact is frightening and even with a century to respond, decommissioning takes a long time to accomplish and disposal of nuclear waste is a nightmare for all of these facilities.

Is a Tsunami possible?

In eastern Canada there is historical evidence of at least five natural tsunamis that have had effects as far south as Bermuda. Some experts believe that conditions exist for potential tsunamis created by new earthquakes or offshore slides.

The 5 known events include … the November 18, 1929 Laurentian Slope-Burin Peninsula event, the Fall 1905-1910 rockslide into Western Brook Pond, an 1864 local earthquake and tsunami seen at St. Shotts on the southwest corner of the Avalon Peninsula of Newfoundland, the September 24, 1848 tsunami seen from St. John’s Harbour to Fishing Ships Harbour in southern Labrador, and the November 1, 1755 Lisbon Tsunami seen in Bonavista, Newfoundland; only the 1929 event is known to have cost human lives.

The earth’s continents are constantly eroding, and the erosional detritus is carried mainly by rivers (but on occasion by wind and by glacial ice) to settle in the sea on the continental shelves. Ocean waves and tidal currents sort the material over time and move it to, and over, the continental shelf edge. Until the early 1950s, the processes of moving these erosional sediments down into the deep ocean was not really known or understood by earth scientists.

It was an event quite unknown in the lives of most who felt it in Atlantic Canada. The surface wave magnitude (Ms) 7.2 earthquake of Monday, November 18, 1929 struck at 5:02 p.m. N.S.T. in the late afternoon — seventy-five years ago. The hypocentre was some 18 km below the seafloor of the northwest Atlantic Ocean, at the mouth of the Laurentian Channel in 2 km of water depth on the continental slope south of the Burin Peninsula on the south coast of what was then the British colony of Newfoundland. It was felt as far away as Montréal, in the New England states as far south as New York City, and there is even a serendipitous felt report in Bermuda of a probable seismic ‘surface wave’; it registered on seismographs around the world. It is still remembered by older residents of the Atlantic Provinces as the only felt earthquake experienced in their lives. Onshore the damage from the earthquake’s shaking was restricted to some slumping and minor building damage in Cape Breton Island; some chimneys were dislocating resulting in subsequent chimney fires in the next few days. Newfoundland, despite its proximity to the epicentre, experienced virtually no physical damage onshore.

Two-and-a-half hours after the event, on a dead calm, bright, moonlit night, on a rising high tide, three main pulses of a tsunami arrived, quite unexpectedly, along the coast of the Burin Peninsula, with amplitudes of 2 to 7 m. There was an initial slow withdrawal of the sea to expose ocean floor in places never before seen by local inhabitants, then the water returned in three positive pulses that rose 2 to 7 m above sealevel. The height and forward momentum of the arriving tsunami caused the runup to rise to as much as 13 m above sealevel at the ends of the long narrow harbours such as Port au Bras, St. Lawrence, Little Lawn Harbour, Lawn, Lord’s Cove, Taylor’s Bay, and Lamaline. Twenty-eight persons lost their lives, and the fishing capability of the coastal communities was devastated.

There was as yet no road to connect the communities to each other or to link the Burin Peninsula to the rest of Newfoundland to the north. Landline telegraph communications with the rest of the Island had been broken by a storm two days earlier, and the tsunami took out the land lines between the coastal communities. In St. Lawrence the telegraph station ended up floating in the harbour. The Burin had to cope on its own for two-and-a-half days before a coastal ferry named the PORTIA, which had a working wireless radio, arrived on the scene. Despite the success of wireless 17 years earlier during the TITANIC disaster, the local communities had no radio sets, and while a wireless was available on the DAISY situated in Burin harbour, no-one knew how to operate it to get a message out!

The tsunami was seen in Cape Breton Island, Nova Scotia, at about 8:00 p.m. A.S.T. on November 18th, where it did minor damage. The one possible death in Nova Scotia has been shown to be false and was based on incomplete information. The tsunami refracted counterclockwise around the Avalon Peninsula to arrive in the Bonavista area about 1:30 a.m. N.S.T. the next morning. The tsunami was physically seen along the coast of Nova Scotia as far southwest as Lunenburg, and in Bermuda at about 8:00 p.m. local time in the evening. It rose in Halifax Harbour, where it flowed over the gates of the commercial drydock at Halifax Shipyards for five minutes and is recorded on the tide gauge record. The only tide gauge operating in Atlantic Canada to record the tsunami was in Halifax; the British had not yet installed a tide gauge anywhere in Newfoundland (or in Bermuda).

Leave a Reply