Several studies undertaken internationally into the effects
of changing world climate have focused on the warming Arctic region along with
melting northern glaciers located across Northern Canada, Northern Russia and
Greenland. While some studies suggest that world sea levels could rise by
between 1.3 and 3-feet by 2100, other more alarming studies suggest that sea
levels could rise by as high as 7-m or 23-feet. Both levels of rise of sea
levels have potential to affect the future of container shipping.
While a rise in sea levels of up to three feet by 2100 would
have little impact on the majority of container terminals internationally, a
rise of over 20-feet presents some very serious implications for numerous
container terminals and requires drastic action in terms of future planning in
terms of terminals and ship technology. A rise in sea levels will increase the
navigation depth and width of downstream areas of waterways. Some rivers that
are presently non-navigable would become navigable to either extreme shallow
draft vessels or to commercial river barges, along with future scope to dredge
several such rivers.
The Small Increase
A three-foot (one meter) increase in seawater levels would
increase channel navigation depth to allow deeper draft ships access to ports
such as Hamburg, Newport News, Norfolk, Charleston, Savannah and Jacksonville.
Such an increase would allow passage to slightly deeper draft ships to sail
along the Russian side of the Arctic and allow slightly more heavily-laden
ships to sail further upstream along such waterways as the Lower St. Lawrence
River and Lower Mississippi River. However, the threat of coastal flooding
caused by ship bow waves would require modifications to ships to reduce bow
waves.
Recent advances in twin-hull vessel technology include
specifically designed modifications to the bow area that redirect the bow wave
under the vessel and between the twin hulls. Another possible method would
involve the construction of a wide twin-hull technology that would attach to the
bow of ocean-going ships of 105-feet beam prior to sailing upriver to a port
such as Montreal. Special ducted propellers or paddle wheels would convert the
bow wave to a fast rearward stream to flow between the main hull and the
outrigger twin hulls so as to minimize erosion to riverbanks.
Inland Ports
A small number of container ports are located inland along
navigable waterways and the list includes Hamburg on the Elbe River, Portland
on the Columbia River, Fuzhou on the Wulong River, Guangzhou on the Shizi Ocean
waterway and Montreal on the Lower St. Lawrence River. While rising seawater
levels would provide greater navigation depth for deep-draft vessels, there
would be need to reinforce riverbanks to prevent future riverbank erosion. With
the exception of Montreal, all other aforementioned ports involve ships sailing
comparatively short distances upstream from the ocean, justifying the expense
of riverbank reinforcement.
While greater water depth along the Lower St. Lawrence River
could transit deeper-draft ocean-going ships sailing between Quebec City and
Montreal, the sailing distance of 140 miles exposes an extended riverbank
distance to potentially accelerated erosion caused by large ocean-going ships
sailing along the waterway. The high cost of reinforcing riverbanks between
Montreal and Quebec City against future erosion would restrict the maximum beam
of Montreal-bound ocean-going ships to 105 feet.
Bridges
Ships sail under a bridge on the approach to several major
world ports. American ports include Port of Newark, Charleston, Savannah,
Jacksonville, Philadelphia, Baltimore, Montreal, San Francisco and the north
side terminals at Los Angeles. Internationally, ships sail under several
bridges on the approach to Guangzhou and also to Montreal. Several years ago,
in preparation to berth new generation Panamax size ships, the State of New
Jersey raised the Bayonne Bridge to allow taller ships to pass beneath. Ships
sailing from the North Sea to the Baltic Sea also sail under a bridge.
Rising sea levels could require the scheduling of ships to
sail under some bridges only at low tide, and some bridges could need to be
raised in the manner of the Bayonne Bridge. Such may be the case for bridges at
the entrance to the Baltic Sea, the bridges between Quebec City and Montreal,
along with the Arthur Ravenel Bridge at Charleston and the Talmadge Memorial
Bridge at Savannah. The combination of rising sea levels and larger future
container ships would likely require that the bridge across the Suez Canal also
be raised to higher elevation.
Waterway Modification
There are numerous non-navigable shallow streams and rivers
along with seasonal streams that empty into the ocean. At the same time, some
shallow draft vessels can sail in as little as one foot of water depth.
Increasing water depth by between two and three feet invites dredging of some
shallow waterways to support small-vessel navigation for some distance going
upstream. Nations such as Bangladesh that depend heavily on waterway navigation
would be able to extend the navigation season along their shallower and
seasonal inland waterways, to the economic benefit of several towns and
villages.
Rising sea levels would increase navigation depth along some
shallow non-navigable waterways that with some minor dredging and levelling of
the riverbed, would allow river barges to operate for some distance upstream
and inland from the ocean coast, carrying containers and even bulk freight. To
minimize possible riverbank erosion, there may also be need to use twin-hull
vessels that redirect the bow wave to flow rearward under the vessel and
between the twin hulls. Communities located along rivers in developing nations
would likely benefit economically from development of waterway transportation
indirectly caused by rising sea levels.
The Massive Sea Rise
Sea levels rising by as much as seven meters (23 feet) would
be the subject of another article. A rise of two to three feet would be
sufficient to affect ship movements at several world container ports. In cases
such as Hamburg and Norfolk/Newport News, rising sea levels would make it
easier for larger container ships to enter and leave these ports while at other
ports such as Charleston, Savannah and Montreal, bridges under which ships sail
could have to be raised to provide greater air draft.