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Broad issues on the State of the St. Lawrence
Progress report and future outlook for improving environmental monitoring
Climate change: current impacts and future disruptions
Day 2 (Wednesday, June 14, 2006, 2:45 p.m.)
Moderator: Serge Lepage, Environment Canada
Panellists:
Alain Bourque, Ouranos
Christiane Hudon, Environment Canada
Denis Gilbert, Fisheries and Oceans Canada
François Morneau, Sécurité
publique du Québec (Quebec Public Safety)
Panellist Presentations
Greenhouse gases (GHGs) in the atmosphere are increasing and temperatures have risen by 0.6°C. The years 2000 to 2005 were among the ten hottest years on the planet. Climate change scenarios are disturbing and Quebec has not been unaffected. There has been gradual warming in southern Quebec, but the warming would appear to be more recent in the St. Lawrence Estuary, Gulf and maritime regions. Contrary to the claims of certain socio-economic players, the debate is now about how widespread this warming will become and how these changes will affect the St. Lawrence. It is anticipated that, in the future, we will observe shrinking ice cover and an intensification of extreme precipitation; there will be fewer storms, but they will be more intense. Moreover, the sea level has already begun to rise; this rise will accelerate. It is known that St. Lawrence water levels have fluctuated since the 1920s; some of these changes have been due to regulation, but environmental factors have also had a great influence. Water levels have fluctuated cyclically. In the 1930s, levels were low (related to the Dust Bowl in the Prairies, among other things). The 1960s were marked by another period of low levels, followed by a rise and then by another drop in water levels, primarily due to warmer temperatures stimulating evaporation, although a precipitation deficit also played a part. GHGs are increasingly dominating the factors influencing climate. Climate scenarios use limited-resolution simulators. The more accurate the simulator, the more thorough our understanding of the short-term impacts. New tools will be required, but we will also have to learn to live with the unknown.
Christiane Hudon, Environment Canada
Christiane Hudon participated in the International Joint Commission (IJC) study. Her area of expertise is the effect of water-level variations and the impacts of human activity on aquatic plants. Climate variations influence water levels in the St. Lawrence, which is fed by the Great Lakes. Since 1990, temperatures have been higher and precipitation less abundant. Increased evaporation has lowered the water level in the Great Lakes and accordingly in the river. In the summers of 1995, 1999 and 2001, levels in the St. Lawrence were particularly low, as they had been in the 1930s and 1960s. Variations in water levels have significant impacts, particularly in Lake Saint-Pierre, where the wetland dynamics are a reflection of water-level conditions. A chronic water level reduction would profoundly transform the lake habitats. Under low-level conditions, an increase in the density of aquatic plants reduces water circulation in shallow areas and could induce lower day-to-day concentrations of dissolved oxygen (hypoxia, anoxia). Increased temperatures are accompanied by a longer growing season for plants and animals, with earlier springs and later falls. Ice jams could occur in February instead of April. Given more concentrated and harder rainfalls, there is a risk of very rapid flooding of tributaries, which may cause serious erosion and municipal sewer overflow problems. During these overflow events, effluent is discharged raw (untreated) into the receiving water, thus considerably increasing the input of nutrients to the river. Excessive concentrations of nutrients foster the development of blue-green algae (cyanophytes), occasionally leading to episodes of toxicity. Climate change could also cause a number of southern species to expand their ranges to areas along the St. Lawrence. All of these elements may lead to enormous changes, be they positive or negative. It should be noted that, in support of environmental education, articles and a kit on climate change for students are available from the Ouranos Web site.
Denis Gilbert, Fisheries and Oceans Canada
With an anticipated rise of 50 cm or more in the sea level by the end of the century, we can expect a westward migration of the saltwater wedge currently present in the Île d’Orléans region. This migration would be stronger if it were accompanied by a reduction in the flow rate of the St. Lawrence. As the presence of winter sea ice is vital to breeding seals, significant impacts on these animals could be anticipated if the ice cover were to shrink. Shrinking ice also threatens to aggravate coastal erosion problems since, in the absence of ice, stronger waves will break on the shores in the winter. On land, we are observing the northward migration of species from the south. Some marine species could move north, but we could also see the inverse: capelin, for example, have recently reached into the eastern portion of the Scotian Shelf. Although models of the marine environment exist, climatic predictions for gulf waters remain a tremendous challenge as there is a lack of reliable information on future inflows of water from the straits of Cabot and Belle Isle. The ocean serves as a heat buffer and can govern the pace at which the climate will change. We may, however, ask whether the oceans will continue to capture GHGs at their current pace. Their absorption capacity could well decrease in the near future. Argo, a global temperature and salinity observation network, was set up in 2004 to monitor the situation and thus allow us to obtain a clearer overall picture of the evolution of ocean climate.
François Morneau, Sécurité publique du Québec
Coastal erosion is a natural phenomenon that has always existed. Over the past few years, however, it has greatly increased, in both breadth and range, with current observations indicating that up to 60% of the surficial deposits that constitute 45% of the shoreline on the North Shore are eroding. Risk-zoning maps have been drawn to factor this new issue into land-use planning. An awareness campaign has also been run in municipalities to heighten awareness of this evolving issue and of the pressing need to adapt to this new situation. The past being no guarantee of the future, the precaution principle must be taken into account. As such, Ouranos has been asked to provide climate information to help guide extensive zoning plans. Very recently, Hurricane Katrina had a huge impact on the North Shore, equalling that of the Saguenay flood. Tropical Storm Rita also caused a great deal of damage by driving large volumes of material onto the shore in built-up coastal areas. In addition to storms, the freeze-thaw cycles that are very prevalent in these latitudes greatly influence the phenomenon of erosion. Protective winter ice cover shrinks every year, to the extent that, as predicted, there was no ice this past winter. All this to say that erosion records have been broken over the past few years. The challenge is to try to use the past to predict the future. Contrary to the climate scenarios that have been developed, extreme weather events seem to be occurring earlier than predicted in the St. Lawrence. To monitor changes along the coast, more than 3800 markers have been installed to keep tabs on erosion. We must now help municipalities adapt to these new, shifting conditions.
With respect to the planned characterization of erosion and risk zoning on the North Shore, some stakeholders asked why the interdepartmental committee report had still not been made public. Others were more specifically interested in the impact of water-level regulation in the context of climate change that could already greatly influence river levels. The major concern is whether regulation can have benefits downstream of Cornwall, and which adaptive measures should be adopted. It would appear that we can hope to benefit from regulation. It must be kept in mind, however, that Lake Ontario has already suffered considerable pressure from its being used as a reservoir to mitigate the negative impacts of commercial navigation. This buffer effect is detrimental to the range of seasonal variations that results in negative effects on wetlands and on the ecosystem. In the wake of studies conducted by the IJC, Environment Canada suggests that the selected plan be closest to natural changes. However, episodes of very low levels may generate strong pressure to “artificialize” or degrade the system. Requests to conduct dredging operations are on the increase, both for pleasure and commercial navigation, and shorelines are subject to numerous human modifications. The floodplain has been encroached upon for the purposes of building on or farming the land, to the detriment of wetlands. There is a growing consensus about the need to minimize human interventions so as to preserve the natural environment. Education and awareness remain an important challenge. Adequate preparation seems to be the key to increasing our adaptability.
There were some questions as to whether the State of the St. Lawrence Monitoring Program could include an overview of climate change based on the work of Ouranos and the IJC, among others. Although little information is yet available on the topic, a great deal of work remains to be done to integrate it all. Some impact indicators could eventually be defined.
In short, if an attempt is made to draw up a balance sheet of climate change and to compare gains and losses, certain positive findings emerge, particularly from an economic point of view. Individual interests are quite diverse and perceptions very different. Based on available information, however, it appears obvious that the many major risks outweigh any potential gains. In this regard, it should be noted that certain sectors are currently experiencing the negative impacts of these changes. This is particularly the case on the North Shore and Chaleur Bay, where the coastal marshes are regressing and exposed to severe weather, as are shellfish harvesting areas.
A great deal of awareness and education work remains to be done on this issue. With regard to shoreline development, individuals decide for themselves, pitting personal interest against collective interests and acquired rights. Municipalities can sometimes be in conflict of interest. Do they have the will to prevent development projects in floodplains? There is a human dimension that cannot be ignored. Community rights are being flouted to the benefit of a few individuals.
Generally speaking, the debate on the issue of climate change seems to be taking place on two levels. On the one hand, the scientific debate is focused more on the parameters to be studied and on quantifying the potential impacts; on the other, the public debate is centred more on the general problem of climate change. The situation has evolved a great deal over the past 15 to 20 years, however. Over 100 countries have signed an agreement on climate change. The challenge for the public at large is to continue to accept the reality of climate change in the midst of a temporary cooling period while, on the global scale, the climate is well and truly warming up. Moreover, we must keep in mind the impact of natural geological phenomena, such as volcanoes, which can lower the temperature curve.
It would be worthwhile to determine, from the perspective of a monitoring program, whether it is possible to link certain vulnerability and adaptation indicators with climate change. Examples cited thus far include water temperature and levels in the St. Lawrence, and certain biological indicators such as wetland surface areas and productivity.
Date modified: 2008/05/01 – Important Notices
