Looking Ahead at Great Lakes Weather Changes


By Harry Valentine 2017-11-19 19:54:53

Climatologists have offered two conflicting long-term forecasts in regard to future rainfall over the watershed region of North America’s Great Lakes and the river that flows to the North Atlantic. Each forecast will influence future shipping on the Great Lakes and along the St Lawrence Seaway.


Outside of the cold northern winter, much bulk shipping occurs on the North America’s Upper Great Lakes and along the St Lawrence Seaway that connects the lakes to the North Atlantic. Over the past decades, weather conditions have caused water levels to rise and fall on the Great Lakes and along the Seaway. During such times, ships have to sail at reduced load and with great loss of revenue income. On other occasions such as the spring of 2017, water levels have risen to levels that threatened shipping along the St Lawrence Seaway. 

Within the past three years, periods of high water levels along sections of the Mississippi River temporarily suspended inland waterway transportation. During periods of low water levels, barges carried reduced loadings with the threat of suspension of waterway transportation. 

For future inland maritime operations, climatologists have offered two scenarios of future precipitation over the watershed regions of the Great Lakes and the navigable inland waterways that connect between the lakes and the ocean. One scenario suggests a future reduction in precipitation over the watershed regions while another scenario suggests increased future summer-time precipitation.

Future Weather Patterns

During summer, prevailing winds blow over the warm water of the Gulf of Mexico picking up intense humidity that is carried northward and inland over the continental U.S. and into Southern Canada. One future weather scenario suggests that warmer seawater would increase evaporation over the Gulf of Mexico with summer winds carrying additional humidity northward and including over the watershed area of the Great Lakes, St Lawrence Seaway and Mississippi River. A variation of this theory suggests that most of the rainfall would occur south of the Great Lakes watershed areas.

During future warmer winters, the Great Lakes could have less ice cover with increased winter evaporation that would cause a decline in water levels. The regions around the Great Lakes could experience increased winter precipitation with higher springtime water levels along rivers that flow into the St Lawrence River. Another scenario suggests delayed future ice buildup and increased winter evaporation in the southern Arctic region, potentially increasing winter precipitation over the Great Lakes watershed area. The inland maritime transportation sector and hydroelectric power generation sector are expected to formulate future strategy based on these forecasts.

Convergence of Events

Future weather projections that pertain to the Great Lakes and St Lawrence Seaway coincide with future weather projections for the Arctic region. A future warmer northern summer could allow trans-Arctic maritime transportation through navigable northern Canadian oceanic channels. The variety of vessels could include future mega-size container ships of 28,000 TEUs and possibly larger sailing to an Eastern Canadian transshipment terminal, where containers would be transferred to smaller vessels sailing to multiple ports located along the east coast and inland waterway. Water levels along the inland waterway would determine the choice of technology that would carry containers.

Water resource planners in the U.S. are hoping for increase future water levels on the Upper Great Lakes as such a development would allow for the construction of a pipeline that could carry potable water to southwestern American states. If future water levels do rise to the point if suspending shipping along the St Lawrence River, then a water diversion to California and Nevada has merit. Future elevated water levels along the St Lawrence Seaway would require ships design with hulls that deflect the bow wave under the vessel, with minimal residual bow waves to erode the shore.

Future Waterway Technology

The technology that sails along the inland waterways would have to be designed for the results of possible future weather patterns. High water levels would restrict shipping for reasons that include the bow waves. Some initial research has already been undertaken in the southern U.S. on a hull design capable of deflecting most of the bow wave under the vessel. Such hull design would be applicable along both the Mississippi River and St Lawrence River. Vessel research and development intended for the Mississippi River could likely be applied to the future vessel development for the St Lawrence Seaway.

Lower future water along the St Lawrence Seaway could justify lengthening the navigation locks and installing water-saving side reservoirs. The locks would them be able to transit extended length, shallow-draft barge trains that sail between Montreal and Lake Ontario. There may be need to reactivate the Murray Canal for commercial transportation, for coupled barges to bypass the rough waters on the east side of Lake Ontario. Special towing technology would need to be developed for a single tug to pull multiple barges across the Gulf of St Lawrence and into the mouth of the St Lawrence River.

Suspending Waterway Transportation

During the every winter, the St Lawrence Seaway upstream of Port of Montreal closes to shipping as does the Strait of Canso between the Gulf of St Lawrence and the Atlantic Ocean. During recent periods of high water levels, maritime transportation was temporarily halted along sections of the Mississippi River. Future prolonged severe droughts could reduce water levels along navigable inland waterways and result in a suspension of ship transportation. Transportation costs would rise dramatically as mainly bulk transportation along both the St Lawrence Seaway and Mississippi River system shifts to the railways. 

Navigating Shallower Waterways

Future weather conditions could reduce water levels along the St Lawrence as sea levels rise, a combination that could help the Port of Montreal to remain operational. Lower future water levels in the Lower St Lawrence River would change ships transportation to and from Montreal. Ships such as the Maersk Pembroke class would still be able to operate between Montreal and Rotterdam-Antwerp. The opening of container transshipment terminals at Cape Breton would allow wider, shallower draft vessels to operate the Montreal – Cape Breton service, included two-section coupled versions that could sail across the Gulf of St Lawrence.

During the 1970’s, the Indian maritime sector commissioned a submersible vessel capable of carrying several smaller vessels that originated from multiple Indian ports, on voyages across the Arabian Sea between India and the Persian Gulf. Low water levels on the St Lawrence River could prompt a re-examination of this concept for possible service across the Gulf of St Lawrence between Cape Breton and the mouth of the St Lawrence River near Bay Comeau, Quebec. Variations of this technology could include extended length rigid vessels and two-section coupled versions that sail across the Gulf of St Lawrence.

Barge Vessels

Semi-submersible technology could carry barges of 450 feet (137 meters) length by 72 feet (22 meters) beam by 18 feet (5.5 meters) draft across the Gulf of St Lawrence between Cape Breton transshipment terminals and the mouth of the St Lawrence River. These vessels could be designed to carry over 400TEUs each and be coupled two widthwise and three lengthwise for sailing between the mouth of the St Lawrence River and Montreal. Alternatively, special towing technology could allow super-tugs to pull groups of barges across the Gulf of St Lawrence. Upstream of Montreal, pairs of barges would be coupled lengthwise with a tug pushing and navigating.

While one weather scenario suggests that future weather patterns could reduce water depth along the Upper St Lawrence River, perhaps by up to two meters, extended length coupled barges that sail at shallow draft could feasibly carry bulk cargo as well as containers. If reduced precipitation over the watershed regions of the St Lawrence River result in reduced navigation depth over a long-term period, it could become feasible to change the technology that sails and the navigable inland waterway that connects the Great lakes to the Atlantic.


Climatologists have offered two conflicting scenarios in regard to future water levels in North America’s Great lakes. With lower water levels in the Great lakes, maritime technology options could sustain viable and cost-competitive maritime transportation between Port of Montreal and ports currently under development at Cape Breton.

A prolonged drought resulting in minimal water depth along the St Lawrence Seaway would result in a massive increase in transportation costs as freight movement shifts to the railway. With higher water levels in the Great Lakes and along the St Lawrence Seaway, vessels that redirect the bow wave under the hull could still carry freight between the Gulf of St Lawrence and Great Lakes.

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.