Canada is influenced in many ways by the three bordering oceans - Pacific, Arctic and Atlantic - and climate change impacts on the oceans affect Canada's people and economy. All of the world's ocean basins have been warming on average, due to greenhouse gas forcing (see Section 1.2), and this is expected to continue. The warming is resulting in rising mean sea level and changes in biological systems, including shifting distributions of fisheries and coral reef bleaching in tropical areas. Sea-level rise is projected to continue for several centuries, even if atmospheric greenhouse gas concentrations are stabilized, due to the lag time involved in thermal expansion of ocean waters and melting of land ice. At the same time, increased storminess has resulted in significant increases in wave heights in many parts of the world's oceans (see Section 1.2). Melting of ice on land is changing salinity as well as adding to sea-level rise, and increased CO2 absorption is increasing the acidity of ocean waters.
The impacts on marine biological systems and fish distribution have been documented in the assessment reports of the Intergovernmental Panel on Climate Change, such that a Growing recognition of the role of the climate-ocean system in management of fish stocks is leading to new adaptive strategies based on determination of acceptable removal percentages of fish, and stock resilience. (McLean et al., 2001, p. 345).
3.1 ATLANTIC OCEAN AND LABRADOR SEA
The atmosphere over the Atlantic Ocean has changed, and will continue to change, with observed and projected increases in storminess and more frequent occurrence of intense hurricanes (see Section 1.2). Climate warming, which will generally be more pronounced in northern regions, will lead to reductions in sea ice. The increased melting of the Greenland Ice Sheet and other land glaciers, and greater precipitation will result in more freshwater inflow to the North Atlantic, thereby reducing its salinity (Intergovernmental Panel on Climate Change, 2001a). The volume-averaged temperature increase at depths of 0 to 700 m depth in the North Atlantic from 1960 to 2000 has been 0.2ºC, but there has been little trend in sea-surface temperature in the northern North Atlantic (Barnett et al., 2001; Pierce et al., 2006).
The strength of the meridional overturning circulation (MOC), also called thermohaline circulation, will be reduced if the waters of the Greenland, Norwegian and Labrador seas are warmed and/or freshened, both of which are projected to occur with climate change (Intergovernmental Panel on Climate Change, 2007a). Reducing the MOC results in reduced transport of warmer near-surface water from the subtropical gyre to high latitudes, counteracting overall global warming. As a result, the North Atlantic would warm less than other areas at corresponding latitudes, and it is possible that parts may cool in the next few decades, although there is uncertainty in the geographic distribution (Stocker et al., 2001). Although the MOC is expected to slow during this century, it is very unlikely to shut down (Intergovernmental Panel on Climate Change, 2007a). Adaptation to address the abrupt climate change that would occur with shutdown of the MOC, and implications for climate policy and decision-making, have not been researched (Hulme, 2003). Nevertheless, reducing the MOC will not cause the onset of the next ice age (Berger and Loutre, 2002; Weaver and Hillaire-Marcel, 2004).
With warming, there will be reduced sea-ice cover over the North Atlantic Ocean, which will make the ocean more open to atmospheric influences. Increased storminess (Lambert, 1996; Lambert and Fyfe, 2006) and possibly more intense hurricanes undergoing extratropical transition, such as Hurricane Juan (2003), will lead to higher ocean-wave conditions. There is now considerable evidence of increasing storminess and higher wave climates in the North Atlantic, including the Grand Banks (Gulev and Hasse, 1999; Gulev and Grigorieva, 2004) and, as the climate warms, most regions of the midlatitude oceans will see an increase in extreme wave heights (Wang et al., 2004; Wang and Swail, 2006a, b). In the near term, there could be more icebergs due to increased melting of the Greenland Ice Sheet and other calving glaciers.
These impacts are affecting fisheries, offshore oil and gas operations, exploitation of other natural resources of the ocean and marine transportation. Reduced sea ice will mean less of a hindrance to marine shipping and fisheries vessels, but storminess and higher waves will adversely impact fleets and energy exploration activities, and increase the risk of marine accidents. Sea-level rise will affect coastal zones around the Atlantic Ocean, with impacts on the habitat of fisheries and creation of new tidally inundated areas. Sea-level changes can also affect the usefulness of port facilities, both overseas and at home, and affect international competitiveness. There will likely be a need for increased search-and-rescue capacity for the North Atlantic Ocean.
Marine fisheries provide an important food source and are a vital part of the economies of Atlantic Canada (see Chapter 4) and other countries, especially in Europe, that border on the North Atlantic Ocean. Historic variations in fisheries across the North Atlantic, beyond Canada's traditional fishing areas, are well documented. In the early 1950s, for example, the stock of Norwegian spring-spawning herring was the world's largest herring stock and was important to Norway, Iceland, Russia and the Faroe Islands (Vilhj álmsson et al., 2005). In 1965, a sudden and severe cooling of these waters resulted in the decimation of the most important food for these herring. The stock was also severely overfished and collapsed. Restrictions on the fisheries and favourable climatic conditions later contributed to the stock's increase and the need for international agreements to set quotas. Such agreements may be an important management tool in the future as climate change alters fish stocks and their ranges.
The disappearance of the North Atlantic cod has demonstrated the social and economic costs of changing fish stocks on Atlantic Canada. The disappearance of the cod was, in part, due to colder waters in the Labrador Sea, as well as overfishing, and the stocks have not recovered as was originally assumed after fishing pressure was reduced (Drinkwater, 2002, 2005; Barange et al., 2003). The relationships with climate have been reviewed by Drinkwater (2002, 2005) and Barange et al. (2003). Generally, as stocks have reduced, they have become more sensitive to climate variability or change, due to shrinkage of the age distribution and geographic extent (Brander, 2005). Although warming waters are likely to promote the recovery of the northern cod stock (Drinkwater, 2005), an increase in abundance of the main forage fish, capelin, and a decline in seal abundance are likely necessary for recovery to occur. The northern cod situation demonstrates how fishing, climate change and other factors affecting marine ecosystems may interact strongly at the extremes of the range of a species. A lightly exploited stock may show few drastic changes as climate and other factors change; however, as in the case of northern cod, such changes may amplify the effects of overfishing, causing negative and sudden changes in vital survival rates and abundance, as well as distribution (Rose et al., 2000; Rose, 2004; Drinkwater, 2005).
As fish are international resources, competition in the open ocean and for species that straddle international borders has led to major disputes. The 1982 Law of the Sea Convention has provisions that enable coastal states to establish Exclusive Economic Zones (EEZs), extending up to 200 nautical miles (360 km) offshore, where they have sovereign rights over the natural resources. Countries are expected to manage these stocks in a sustainable manner. With the dramatic increase in fishing beyond the EEZs in the 1980s, and increases in catches within the EEZs due to rapidly growing fishing capacity, the 1995 UN Convention on Straddling Fish Stocks and Highly Migratory Fish Stocks mandated the application of a precautionary approach to fisheries management and emphasized the need for co-operation between countries. The Northwest Atlantic Fisheries Organization (NAFO) and the North East Atlantic Fisheries Commission (NEAFC) were formed and led to ecosystem-based approaches to the management of living marine resources, where natural factors such as climate change are taken into account in decision-making. The 2002 World Summit on Sustainable Development stated in its implementation plan that such ecosystem-based approaches to management are to be in place by 2010.
The Arctic Climate Impact Assessment provided a detailed analysis of Arctic and North Atlantic fisheries (Vilhj álmsson et al., 2005), concluding that it is not possible with present knowledge to provide precise forecasts of either changes in the fish stocks and fisheries or the effects on society, due to uncertainties in:
- identifying the reasons for historical changes in fish biology;
- predicting possible changes in the ocean climate under the scenarios of climate change; and
- understanding the relationships between socioeconomic factors and changes in fish stocks.
Further, since many of these fish stocks are heavily exploited, they are currently much lower in abundance than in the past and are exhibiting extreme changes in population characteristics. Nevertheless, some general conclusions can be drawn with respect to the impacts of climate change on fisheries and the related economies in North Atlantic -Arctic countries. Warming will be a benefit for some species, whereas it will create problems for others. Changes need to be seen in the context of an overall economy, its diversification and its ability to adapt - politically, socially and economically. It is important for Canadians to understand the impacts in other countries and to project how other countries may respond, so as to understand the consequent impacts on Canada. There is need for further analysis in this regard.
Another issue related to climate change in the marine environment is the altered risks of poisoning of fish and shellfish for human consumption and impacts on ecosystems. Warmer waters could result in an expansion in the ranges of toxins to higher latitudes and increase the occurrence of toxic algal blooms (Berner et al., 2005). There could be impacts on human health that will need to be accounted for in both domestic production and import of seafood.
Climate-related changes can also affect the competitive nature of fisheries systems globally. Impacts that reduce fish in other regions of the North Atlantic may result in additional pressures from their fishers to utilize Canadian waters. Impacts on commercial shellfish may be of most significance.
Atlantic Ocean Warming and Tropical Storms
Waters of both the North Atlantic and South Atlantic oceans have been warming since the 1950s, from near the surface to depths of >100 m, with much of the warming attributable to increasing greenhouse gas concentrations (Barnett et al., 2001; Pierce et al., 2006). Several analyses of the frequency of intense hurricanes and more long-lived storms indicate a significant trend towards more categories 4 and 5 storms in the past 30 to 35 years (Emmanuel, 2005; Webster et al., 2005). Some hurricane forecasters attribute the recent increases entirely to cyclic changes, but analysis of the relative importance of climate change and cyclic changes suggests that global warming trends account for two-thirds of the increase in categories 3 to 5 hurricanes (Faust, 2006). Thus, more intense hurricanes are to be expected on average in the future as the ocean continues to warm. This suggests the need for better disaster preparedness and management for hurricanes in the Caribbean, coastal areas of the United States and maritime Canada, and increased demand for disaster preparedness and recovery assistance (see Section 2.2).
3.2 PACIFIC OCEAN
Average warming off the British Columbia coast was minimal between 1901 and 1979, but occurred at a rapid rate of up to 0.25 °C per decade between 1979 and 2004. Much of the warming in this recent period has occurred in June, July and August (data from the National Climatic Data Center; Smith and Reynolds, 2005). The trends observed in the North Pacific are, in part, related to the Pacific Decadal Oscillation (PDO), which is, in turn, linked to the El Ni ño Southern Oscillation (ENSO). These two circulation phenomena result in alternating warm periods (1935 -1945 and 1975-2004), accompanied by a deeper Aleutian Low, and a cool period (1945-1975) in the eastern North Pacific. These major fluctuations and longer term warming trends appear to both be at work, reinforcing each other in warm phases. Some oceanographer-meteorologists think that anthropogenic climate change stimulates the warm phase of the PDO and ENSO (Corti et al., 1999; Timmermann et al., 1999).
At the same time, with the frequency of intense winter storms in parts of the Northern Hemisphere increasing (McCabe et al., 2001), changes in significant wave heights have been observed. From 1950 to 2002, significant wave heights have increased about 1 cm per decade off British Columbia's coasts (Gulev and Grigorieva, 2004). Such increases are projected to continue (Caires et al., 2006).
Sea-level rise and an increase in intense storms are resulting in flooding and erosion episodes and related water quality problems on the west coast, especially in the lower mainland (see Chapter 8).
With continued warming of the eastern North Pacific, the population distribution for sockeye salmon will be compressed, forcing them increasingly into the Bering Sea (Welch et al., 1998; Beamish et al., 1999). Figure 6 shows the current thermal limits for sockeye salmon in December (upper panel) and July (lower panel). The 2 x CO2 climate projections show this thermal limit retreating to the Bering Sea (Welch et al., 1998), out of reach of most Canadian fishers. While it is expected that changes in total numbers may be small, changes in regions of occurrence will mean that a particular species will be caught by fishers from different countries. For anadromous fish, warming water in spawning rivers may also change the populations and ranges of certain fish stocks (see Chapter 8).
Aquaculture in coastal waters could benefit from warmer conditions, with increased growth rates and an increase in the geographic range of the activity. Higher water temperatures and related physical changes could, however, result in more intense and frequent disease outbreaks and algal blooms (Kent and Poppe, 1998). Bacterial contamination of oysters and other shellfish may be more frequent as water temperatures rise. The increased frequency of intense winter storms and the trend towards higher wave heights would also physically endanger aquaculture operations.
Fishers would be affected in several ways by the changing climate. They may need to go farther from home ports to catch their quota of a particular species. This exposes them to increasing hazards from the more frequent intense winter storms and higher waves off the west coast. In addition to such safety concerns, the changing fish populations may make it necessary to adapt by modifying the kinds of fish they catch and where they catch them (Beamish et al., 1999; see Chapter 8).
Tourism in western coastal waters will be affected in similar ways. Generally, small recreational boats would require greater attention to safety because of higher waves and greater incidence of severe storms. Sea-level rise and severe storms would also have negative effects on marinas and other coastal infrastructure used for fisheries and boating, which may require expensive adaptation measures to maintain (see Chapter 8)
Although the most favourable ship routings across the Pacific may change as circulation, winds and storm patterns change, the main impact on shipping is likely to be through ports and shore infrastructure. In Japan, for example, it has been estimated that a 1 m sea-level rise would require an expenditure of US$110 billion to maintain present functions and stability in their 1000 ports (McLean et al., 2001). In British Columbia, reinforcement and raising of breakwaters and wharves will likely be required to adapt to higher water levels and the greater wave regime, to ensure that Canadian ports remain internationally competitive (see Chapter 8).
3.3 ARCTIC OCEAN
Little international shipping takes place in the Canadian Arctic at present. Port and docking facilities in the Canadian Arctic are rudimentary, with the exception of the Port of Churchill, Manitoba, on Hudson Bay, which has four deep-sea berths for grain, general cargo and tanker vessels. In 2002, Manitoba and the Russian province of Murmansk -the European gateway to the Northeast Passage-signed a letter of intent to develop a marine link between the two provinces. Dubbed the 'Arctic Bridge', this concept is to develop further the Port of Churchill as part of a North American trade corridor. This concept is deemed viable as a result of the longer sea ice -free shipping season in Hudson Bay and the Davis Strait. It has been suggested that there should be development of port facilities at Iqaluit to assist regional economic growth (Aarluk Consulting Inc. et al., 2005). The duration of ice cover in the Canadian Arctic Archipelago is projected to be reduced by one month by 2050 and by two months by 2090 (Dumas et al., 2006). However, there would still be significant ice hazards for ship transits (see Chapter 3). Base-metal mines, including the Polaris lead-zinc on Little Cornwallis Island and the Nanisivik zinc mine on northern Baffin Island, were supplied by sea, and concentrate was shipped to smelters in Europe and elsewhere. However, these mines ceased operations in 2002 and 2003, respectively, leaving the Raglan nickel-copper mine in northern Quebec and the prospect of a huge nickel mine at Voisey's Bay in Labrador to be serviced by sea. The mining industry hopes to develop port and road facilities in or near Bathurst Inlet to service and supply exploration and development operations for precious and base metals and diamonds in the Kitikmeot region and northern Northwest Territories (see Chapter 3).
A considerable increase in international use of the Canadian portion of the Arctic Ocean seems likely. The Arctic Climate Impact Assessment (ACIA) concluded that:
“The continued reduction of sea ice is very likely to lengthen the navigation season and increase marine access to the Arctic's natural resources.” (Arctic Climate Impact Assessment, 2004, p. 11)
Further, the ACIA suggested that trans-Arctic shipping during the summer is likely to be feasible within decades. Diminished sea ice in summer in the Canadian Arctic could prompt the world's shipping community to seek expanded access to the Northwest Passage (Figure 7) to convey international cargos, taking advantage of the shorter sea route from eastern Asia and the west coast of North America to the eastern seaboard of North America and western Europe. Most climate models suggest that these sea ice changes will occur in the latter half of this century (Walsh et al., 2005), although recent trends suggest an earlier date. However, opening of the seas north of the Russian Federation is likely to occur earlier, and infrastructure to support marine traffic along that route will probably develop before that in Canadian waters.
To follow up on the ACIA, Arctic Council ministers in 2004 initiated an Arctic Marine Shipping Assessment (AMSA). To be presented to ministers in 2008, the AMSA will provide a 'snapshot' of Arctic shipping in 2004 and projections of the likely level of shipping in the circumpolar Arctic in 2020 and 2050, in light of sea-ice ablation, economic development scenarios, and risks such as the possibility of increased ice hazards in some regions.
Fisheries and the Food Chain
Water temperatures and ice cover influence the distribution of Arctic fish and marine mammals, as do changes in freshwater input from the major rivers of Russia and Canada (Arctic Monitoring and Assessment Program, 2002). Along the North American coast, important fish stocks, such as Atlantic cod and herring, are being displaced due to warming waters - moving northeastward where they will be more accessible to fishers from Scandinavia and Russia. Loss of estuarine ice may displace cisco. Loss of sea ice results in Arctic shelf seas looking more like temperate seas, with implications for food web structures that are difficult to predict. One surprise and warning sign was a massive bloom of jellyfish in the Bering Sea in the 1990s (Arctic Monitoring and Assessment Program, 2002).
Pupping of ringed seals, which provides a favourite food source for polar bears, requires extensive sea ice. A decrease in suitable habitat could affect the entire upper food chain, since the seals prey on Arctic cod. For Canadians of the Arctic, the catching of fish or seals for food requires longer voyages into the Arctic seas, which are increasingly hazardous because of the trend towards more severe winter storms (see Section 1.2). This leads to significant changes in the way of life for some Arctic communities (see Chapter 3).
Contamination of the food chain is also a concern. As permafrost melts, more mercury is released to rivers and the ocean, and accumulates up the food chain. Mercury and other contaminants from more southerly latitudes can have adverse effects on people of the Arctic, especially indigenous women. Women of Baffin Island, Nunavik and Greenland have been found to have very high mercury concentrations in their blood and breast milk. Seal meat and fish are significant food sources for these populations (Arctic Monitoring and Assessment Program, 2003).
Industrial development in the north is likely to add to contamination of the Arctic seafood chain. Development of natural gas and oil deposits at Hammerfest, Norway is proceeding apace with reduced ice. Oil reservoirs have been identified 320 km from the North Pole, and the Shtokman field in Russian parts of the sea is thought to be the largest offshore gas reservoir in the world. With global warming and loss of Arctic sea ice, development of these resources is becoming increasingly feasible (see Chapter 3).
Persistent organic pollutants (POPs), including hexachlorocyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), toxaphene and polychlorinated biphenyls (PCBs) of industrial and agricultural origin, and some heavy metals, have been detected throughout the circumpolar world at unexpectedly high levels (Indian and Northern Affairs Canada, 1997). Sources of POPs within the Canadian Arctic, including PCBs from Distant Early Warning (DEW) line sites, are minor compared with long-range transport from the south (Europe, Asia and North America). Bioaccumulation and biomagnification of POPs in the Arctic environment have resulted in elevated levels of some POPs in lipid tissues of animals, particularly marine mammals, including beluga whales, narwhal, walrus, ringed seal and polar bears. As a result of eating marine mammals, some Inuit have levels of some POPs in their bodies that are known to have effects on the immune system and on neurobehavioural development and reproduction (Dewailley and Furgal, 2003).
Macdonald et al. (2003) noted that increased global temperatures will have direct effects on contaminants through enhanced volatility, more rapid degradation and altered partitioning between phases (Macdonald et al., 2003). Changes in the timing and length of seasons are likely to be particularly important in changing the spatial distribution and levels of contaminants in the Arctic through long-range transport. The ACIA noted that climate change and pollution in the Arctic are interrelated, and that:
“More extensive melting of multi-year sea ice and glacial ice can result in pulse releases of pollutants that were captured in the ice over multiple years or decades.” (McCarthy et al., 2005, p. 954)
Although the bilateral Canada-United States dimensions of contaminants are most critical for Canada, longer range atmospheric transport is becoming of increasing concern (Indian and Northern Affairs Canada, 1997). Pollutants due to emissions from the rapidly growing economies of China, Japan and southeast Asia are now being detected in Canada's north. Some of these contaminants come through volatilization from waters of lakes, such as the Great Lakes and Asian lakes, where the substances had been earlier deposited through long- and short-distance atmospheric transport. This volatilization occurs in the warm season, with the toxic contaminants gradually moving farther and farther north to where waters are too cold, year round, for the process to occur. This volatilization process will occur more readily as lakes warm in the changing climate. Thus, this contribution to Arctic contaminants from the above-mentioned sources in the Northern Hemisphere will gradually increase. It is presently unknown whether changes in atmospheric circulation patterns will occur that would either lessen or exacerbate the transport of contaminants to the Arctic.
Canadian Control and Security
Canada acquired sovereignty over the Arctic from the United Kingdom through legal and political measures that stretch back to the 1670 Charter granted by King Charles II to the Hudson's Bay Company. In 1870, the company transferred its title to the Hudson Bay watershed to Canada. Following an address by the Canadian Parliament to Queen Victoria expressing doubt as to Canada's northern border, the United Kingdom in 1880 transferred to Canada all territory in British North America and adjacent islands, with the exception of Newfoundland. Both Denmark and Norway challenged Canadian sovereignty on some islands from 1898 to 1910. However, Canada took several actions to reassert ownership and, with payment of compensation, Norway relinquished its Arctic claim in 1931. An issue remaining is the dispute with Denmark over tiny Hans Island between Greenland and Ellesmere Island.
With Canada's sovereignty to Arctic land secure, attention turned to the ocean, with specific reference to the Northwest Passage. The United States and European Union contend the passage is a strait used for international navigation through Canadian territorial waters, whereas Canada asserts the passage to be internal waters over which it has full jurisdiction and control (e.g. Rothwell, 1993; Charron, 2005). The degree of control that Canada can exercise over these waters depends upon whether they are considered internal waters, as Canada claims, or a strait for international navigation. The 1969 transit through the passage of the American supertanker 'Manhattan' crystallized Canadian concerns and prompted legislative action, including the Arctic Waters Pollution Prevention Act. A similar transit through the passage in 1985 by the American icebreaker 'Polar Sea' resulted in legal action by Canada to draw 'straight baselines' around claimed land and ocean. In 1988, Canada and the United States concluded an Arctic Co-operation Agreement through which future transits through the passage by icebreakers would be undertaken with the consent of Canada. This agreement had no bearing on the legal positions of the parties vis- à-vis the status of the passage. Increased shipping in Canadian Arctic waters will likely require increased surveillance, monitoring, maintenance of navigation signals and search-and-rescue services.