The St. Lawrence is a prime gateway to North America. 100 million tons of cargo are shipped by boat along the St. Lawrence every year.
However, the water levels and the flow of the river may be reduced as a result a climate change, which primarily poses a risk to marine shipping.
Did you know that...
International trade accounts for 75% of Québec's marine traffic.
A River That Is Sensitive to Climate Change
Many factors influence the flow and water levels in the St. Lawrence, and their effects combine in a complex way.
Water levels in the St. Lawrence vary from season to season. The fluctuation in the precipitation/evaporation ratio is mainly a function of summer temperatures. Heat waves with very little precipitation and more evaporation appear to be getting longer and occurring more often.
On the other hand, winter temperatures determine the duration of ice cover. If CO2 concentrations in the atmosphere double, winter temperatures in southern Québec may rise by 4°C by 2100. This would cause the ice to melt, leading to increased flow and higher water levels in winter, which would lengthen the navigation season.
As a result of longer and greater exposure to the action of waves, coastal areas would be more vulnerable to erosion. In this respect, existing voluntary measures to reduce the speed of vessels appear to be producing positive results. In fact, between Montréal and Sorel, these measures have led to an approximately 50 % reduction in the erosion from lapping, or the effect of waves created by passing ships, boats, and pleasure craft. It is now up to boaters and pleasure craft users to do their part.
Water levels also vary from year to year. Annual water levels in the St. Lawrence have been recorded since 1800. The lowest water levels occurred in 1930 and 1960, and the trend today is once again downward.
Many natural factors influence water levels, including most notably the water volume of tributaries, ice jams, and wetlands. Wetlands not only curb the erosion process, but they also act as a natural filter, improving water quality, and are rich in terms of biodiversity and act as breeding grounds for many species.
Certain factors related to human activities contribute to fluctuations in water levels. Dams, dikes, and dredging are some examples. Dredging makes it possible to keep the depth of the shipping lane in the St. Lawrence at a minimum of 11.3 metres so that ships can pass. However, dredging has numerous environmental impacts, and is a contributing factor to coastal erosion.
Affected Marine Activities
Any reduction in the water levels and flow of the St. Lawrence is likely to affect marine transportation.
The expected rise in winter temperatures in Québec will mean earlier spring thaws and later autumn freeze-ups of the St. Lawrence shipping lane. Obviously, higher winter temperatures would lengthen the navigation season, which would obviously have a number of advantages. However, the negative impact of global warming on marine transportation in the St. Lawrence would undoubtedly be much greater.
In fact, for each centimetre the water level drops, a ship has to carry six less containers, or 60 tons less bulk. This would mean that ships have to make more trips in order to haul the same amount of cargo, and in some circumstances, may even have to lighten their load in a downstream port. One major shipping company that uses the St. Lawrence has already modified the design of its new ships in order to maximize their loads in response to low-water periods.
Did you know that...
Montréal is the third busiest container port on the Eastern Seaboard.
Encouraging Sustainable Marine transportation
Towards a Strategy for Sustainable Navigation on the St. Lawrence
The Ministère des Transports du Québec (MTQ) is a member of the Action Plan Navigation Committee for Phase III of Saint-Laurent Vision 2000. This Committee, which developed the Sustainable Navigation Strategy and the means for its implementation, consists of some 20 provincial and federal government representatives and another 10 representatives from non-government organizations. The sustainable navigation strategy proposes managing commercial and recreational navigation activities and practices in harmony with environmental requirements, ecosystem protection, and the implementation of other uses. It focuses mainly on an integrated plan for managing dredging and sedimentation, preventing the effects of lapping, managing wastewater and shipping residue, and assessing the options for adapting navigation to the expected lower water levels.
A Marine and River Transportation Policy
In 2002, the MTQ adopted a Marine Transportation Policy. In keeping with the policy statement, the government formed a marine transportation coordinating forum (Forum de concertation sur le transport maritime) which comprises government and stakeholder representatives. This forum, which produced a report on coastal shipping Rapport sur le cabotage and a report on the strategic port network Rapport sur le réseau portuaire stratégique as well as other reports on the development, promotion, and competitiveness of the St. Lawrence, ensures coordinated implementation of the measures proposed in the policy. The MTQ supports the forum by providing funding through its Marine Transport Assistance Program.
Did you know that...
If CO2 concentrations in the atmosphere double, the River’s average annual flow could drop by 40%. The water level at Montréal would then be more than one metre lower.