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Une vague de changement

Bien que personne ne suggère encore que la baie de Fundy deviendra sous peu un lieu de villégiature tropical, la plupart des climatologistes nous avertissent que le climat de la région se réchauffera beaucoup durant les prochains 50 ou 100 ans. L’auteur Jon Percy explique comment l’élévation du niveau de la mer et son réchauffement affecteront la Baie de Fundy.

En plus de l’élévation du niveau de la mer, la terre autour de la Baie de Fundy s’effondre. Ce qui signifie que l’océan pourrait être près de deux pieds plus haut le long de la côte de baie d’ici 2100, ce qui causera des inondations et de l’érosion spécialement durant les tempêtes.

Et les poissons, les crustacés, les oiseaux de rivages, les oiseaux et les mammifères marins subiront certainement les effets de l’augmentation de la température des eaux. Toutefois, les scientifiques hésitent à prédire exactement quels seront ces effets à cause de la complexité des facteurs qui influenceront leur distribution. Néanmoins, si la température de l’eau de la Baie de Fundy augmente par plus d’un degré ou deux, il est probable que nous verrons différentes espèces que celles que nous voyons actuellement.

 

A Rising Tide of Change

Jon Percy
Bay of Fundy Ecosystem Partnership and SeaPen Communications
September 2007

hile no one is suggesting that the Bay of Fundy will become a balmy tropical getaway anytime soon, most climate scientists warn that the region will become much warmer in the next 50 to 100 years.  This warming is already underway and will likely speed up in coming decades.  Gary Lines, a Climate Change Meteorologist with Environment Canada, estimates that the summer temperature at Kentville, Nova Scotia, on the upper Bay, will rise by more than 3°C by the 2050s and by at least 5°C by the 2080s.  Winter temperatures will also increase by 2°C and nearly 4°C, respectively.


Long-term records clearly show that temperature and sea level are already steadily rising all around the word, while the area of snow cover in the northern hemisphere is declining. 
(Photo: Gary Lines)

The warming felt in the Bay of Fundy is part of a worldwide trend almost certainly largely caused by the increasing volumes of greenhouse gases (such as carbon dioxide and methane) that humans have been producing since the industrial revolution.  Fortunately, people are now becoming worried about the threat and even some politicians are finally taking notice.  In his government's recently released “Climate Change Action Plan,” New Brunswick Premier Shawn Graham stated that, “Climate change and its effects…pose a significant challenge not only to New Brunswick but also to the whole world.  These impacts will continue in many forms, and inevitably change the way all New Brunswickers live and prosper in our province.”  Key industries throughout the region such as forestry, farming, and fishing will definitely be affected and the warming trend will unquestionably have profound effects on the Bay of Fundy, its renewable resources, and those who live on its shores.

 Sea Level & Extreme Weather

It seems that almost every newscast carries alarming reports about the melting of polar ice caps, Greenland ice sheets, and mountain glaciers.  This torrent of meltwater pouring into the sea, combined with the fact that as the seawater warms its volume increases, is causing the sea level to rise steadily.  The land around the Bay of Fundy is also subsiding, by almost a foot every 100 years, while the sea is rising by at least 10-15 inches per century.  These two effects together mean that the ocean could be almost two feet higher along the Fundy coast by 2100.  A couple of feet may not sound like much compared to the dramatic 45-foot rise and fall of the tide the upper Bay, but it could spell devastation for many coastal areas.


Many areas of the Bay of Fundy are moderately to highly sensitive to the effects of rising sea level. (Photo: Gary Lines)

There will certainly be more coastal erosion in vulnerable areas around the upper Bay.  More worrisome is that large areas of the Fundy coast are already well below sea level, protected only by earthen dykes or rocky causeways.  Roads, railways, businesses, and homes have spread into many such low-lying areas.  Global warming is expected to bring more frequent and much mightier storms to the Maritimes.  It is only a matter of time before a major nor'easter sweeps up the Bay of Fundy when the tide is high.  The accompanying storm surge will pour over many of the dykes and flood the land and infrastructure behind them.  The dykes will then prolong the flooding for many days by preventing the seawater from draining away as the tide falls.

 Fisheries and Aquaculture

Harvesting wild fish and shellfish, or raising them in anchored cages in sheltered embayments, are mayor contributors to the economy of many communities around the Bay.  Fisheries scientists are largely in agreement that the changing climate is going to significantly affect both these industries, although most are reluctant to say exactly what these effects will be.  There are simply too many complexities in a fish's life cycle and life style that can be subtly influenced by even a slight rise in average temperature for scientists to even hazard a guess as to what might happen to the whole population.  Small changes in temperature can change the rate at which a fish grows, the amount of food it eats, the time it takes to reach maturity and reproduce, the number of eggs it lays, how many eggs hatch, and how many young survive to a fishable size.  In short, almost every aspect of a fish's life story is sensitive to changing temperature.  It is no wonder that scientists are hesitant to make predictions when confronted by such enormous biological complexity, differing in every species of fish and shellfish they study.  Nevertheless, if the average temperature of the Bay of Fundy does rise by more than a degree or two then fishermen will likely be harvesting different species of fish than they do now.


Fishing boats may be harvesting different species if global warming raises the temperature of Fundy's waters significantly. 
(Photo: Jon Percy)

Fish confined in aquaculture cages don't have the option of swimming to where the temperature is more to their liking; they just have to tough it out.  On the positive side, with warmer winters aquaculture operators won't have their stock killed by sudden cold snaps as has happened occasionally.  Warmer water, if only by a few degrees, might make the caged fish grow a bit faster and be ready for market sooner.  However, it may also make them more susceptible to diseases and parasites, particularly several worrisome invasive species that area moving northward with the warming waters.  If water temperatures rise beyond the tolerance limits of the currently farmed species, then aquaculturists, too, may have to switch to other types of fish.

 Shorebirds, Seabirds, & Marine Mammals

Climate change will undoubtedly affect the abundant seabirds, shorebirds, and marine mammals that attract thousands of tourists to the Fundy region each year.  Many of these species are likely to change their distributions in response to warming air and sea.  Many seabirds, such as puffins and terns, breeding in large colonies on many Fundy Islands, may not be able hatch their eggs if extreme weather occurs more frequently in spring and early summer.  Changing sea conditions could also reduce the availability of crustaceans and small fish that the birds depend on to feed their young.  Whales are also likely to change their distribution if the seawater warms significantly, particularly if their abundant food supply in the Bay diminishes significantly.  Endangered right whales may be particularly vulnerable to the changing ocean climate.  Again, scientists are reluctant to predict exactly how seabird and whale populations will change as the sea and air warms because of the complexity of the factors influencing their distribution, life history and reproduction.  They are confident, though, that there will be great changes if global warming continues on its present course.  What this all means for the burgeoning ecotourism industry in the region is anybody's guess.

 The Last Word

Climate scientists are convinced that global weather patterns have already begun changing and that the trend will continue if humans keep producing greenhouse gases at an ever rising rate.  By working together to sharply reduce these inputs we may be able to limit the overall magnitude of climate change and its ecological impacts.  However, we should also start preparing our communities and ourselves for the looming threats of rising sea level, rising temperature, more extreme weather conditions, and bigger and more frequent storms in the Bay of Fundy and elsewhere.