Potential impacts of indirect mechanisms of climate change on human health in the Arctic

Published: February 9, 2010, 4:16 pm

Updated: August 2, 2012, 11:41 pm

Topics:

Human Health (main) Environmental Health (main) Water (main) Ecology (main) Climate Change (main)

[1]

This is Section 15.4 of the Arctic Climate Impact Assessment.

Lead Authors: Jim Berner, Christopher Furgal; Contributing Authors: Peter Bjerregaard, Mike Bradley, Tine Curtis, Edward De Fabo, Juhani Hassi, William Keatinge, Siv Kvernmo, Simo Nayha, Hannu Rintamaki, John Warren.

In addition to direct impacts of climate-related changes on human health, human health in northern communities is affected by a number of indirect impacts. These refer to those health consequences resulting from indirect interactions mediated via human behavior and components of the environment that have changed or are changing with local climate. These indirect effects include critical impact mechanisms such as social and mental stress related to changes in the environment or lifestyle which are related to changes in local climatic regimes. They include such things as effects on diet (decreased subsistence/cultural food species abundance and/or availability) as a result of climate-related impacts on wildlife species or environmental factors influencing indigenous peoples’ access to these resources (e.g., ice distribution, land stability, weather predictability); effects on health as a result of changed access to good quality drinking water sources; effects on rates of diseases resulting from climate effects on sanitation infrastructure; and changes in human disease incidence associated with climate impact on zoonotic diseases.

Changes in animal and plant populations (15.4.1)

Climate change can have dramatic effects on the numbers and distribution of species in an ecosystem and these changes may have significant social, cultural, and health effects on indigenous human populations. All ecosystems are a dynamic equilibrium of species and climate is one of the most important factors in this delicate balance. Climate changes, even subtle changes, may shift this balance to favor some species, stress other species sometimes to the point of extinction, and allow new species to enter the system. Other chapters of this report address the significant and sometimes dramatic affects of climate change on species. Infectious disease agents of plants, animals, and humans are integral components of all ecosystems and may increase, decrease, or spread into new regions as a result of climate change. The dynamics of these changes and how they may affect human health are described in this section.

Species responses (15.4.1.1)

Since the late 19th century, global temperatures have risen by an average of 0.6 ºC with the increases more pronounced at higher latitudes and higher elevations. A review of 143 studies involving range distributions of nearly 1500 species showed that over this period 80% had shifted their ranges toward the poles.These shifts are likely to be greater in polar regions where the temperature increase has been greater.

Increased warming from the mid-1970s to the mid-1990s is thought to have been the major reason for a rise in salmon numbers in the Bering Sea and North Pacific. Salmon is an important traditional food for many indigenous people and an important economic asset in the Bering Sea and North Pacific. However, the increased temperatures also had some adverse health effects. The warming caused increased productivity at all levels of the food chain including increased numbers of those algae which cause toxic red tides and paralytic shellfish poisoning. Extreme environmental events such as flooding which washes nutrients into coastal waters could also increase the occurrence of paralytic shellfish poisoning.

The warming trend that caused high salmon numbers in the North Pacific and Bering Sea may also have been the major factor responsible for the dramatic reduction in Alaska salmon since 1997. Higher water temperatures may have increased salmon metabolism to levels that could not be sustained by existing food sources and spawning salmon were often smaller than normal. A reduction or disappearance of traditional food species may result in indigenous populations switching from a traditional diet to less healthy diets; such dietary shifts are associated with an increased prevalence of chronic diseases such as diabetes, heart disease, and cancer among northern populations. Health effects related to extreme economic hardship could also follow a decline in traditional food species.

Climate change often creates opportunities for species to move into new regions. Species may colonize a region from an adjacent area, through migration or through accidental or intentional transport by humans. In Alaska, recent warming has increased average growing degree-days by about 20%.This has had a significant impact on the ecosystems there. Sustained warming on the Kenai Peninsula in south-central Alaska encouraged a spruce bark beetle infestation and the largest tree death in North America. Northern expansion of the boreal forest has favored the steady advance of beaver in northern and western Alaska. Beaver make dramatic alterations in surface water and fish habitat.They may also expand the range of Giardia, a parasitic disease of beaver that can infect many other animals and humans.

An expansion in the range occupied by beaver has also been reported by indigenous people in other regions of the Arctic.

We see moose now, and never did before.We see them more and more each year.We've seen them up as far as the bay north of here (Nain). Nain, hunter aged 43;

It was maybe twenty years ago that we saw the first beaver track ever up in the bay (Webb’s Bay, north of Nain)…we didn't know what it was. Nain, hunter aged 46

It is not unusual for a few individuals of a migratory species to deviate from normal pathways and arrive in a new region. Every year Alaskan bird watchers are thrilled at “exotic” Asian species that visit local bird-feeders. If the new ecosystem is favorable the species can become permanently established. Climate change may create favorable habitats in regions that could not previously be inhabited. Successful establishment of a new species alters the ecosystem and impacts upon other species. Accidental introductions arising from human activities may also result in colonization. There is concern in Alaska about species transported into the region when ships discharge ballast waters.

Climate change may create conditions in the marine environment that are favorable to species introduced in this manner. The marine ecosystem is vital to subsistence food users and the economies of Alaska and other northern regions. The introduction of competing species or diseases of existing species could be catastrophic for the fisheries and indigenous communities of the Arctic.

Infectious diseases (15.4.1.2)

Infectious disease agents are part of any ecosystem and are also affected by climate change. Stresses posed by climate change may increase the susceptibility of plants and animals to disease agents causing both the rates of infection and severity of infection to increase. High incidences of diseases and die-offs were reported during recent El Niño–Southern Oscillation events. Climate warming during these events has been associated with sickness in marine mammals, birds, fish, and shellfish. Disease agents associated with these illnesses have included botulism, Newcastle disease, duck plague, influenza in seabirds, and a herpes-like virus epidemic in oysters. Diseases that attack species forming habitat for other species, such as seagrass, are also affected and can have devastating environmental impacts. If such effects arise following the temporary temperature shifts associated with El Niño–Southern Oscillation events, then it is likely that temperature changes arising from longer duration climate change will be associated with an increased occurrence of diseases and epidemics.

Species expanding into new regions will expose resident species to any disease agents they take with them. This is the case for beaver and Giardia. Giardia is a waterborne disease, and beaver dams increase the surface water habitat that promotes the spread of the parasite to other animals such as caribou and humans. Infected caribou may also increase the spread of the parasite as they migrate to other parts of their range. Other waterborne diseases are also likely to become a greater risk due to beaver-engineered surface water changes especially in areas where people use untreated surface water.

Species that benefit from climate changes are likely to increase in numbers and create more hosts for disease agents. Expansion of host species into new regions and the reformulation of ecosystems increase the probability of spread to new host species. Species that have not been exposed to a new infectious disease agent are often extremely susceptible to the infection. The catastrophic epidemics in indigenous North Americans following the introduction of smallpox, tuberculosis, influenza, and many other infectious diseases after European contact are such examples.

The West Nile virus is a recent example of how far and fast a disease agent can spread after colonizing a new region. The virus was first identified on the east coast of North America in 1999 and by the end of 2003 had spread to all lower 48 states except Washington and Oregonin the United States and seven of 13 Canadian provinces and territories. Nearly 9000 human cases and over 200 deaths occurred in the United States in 2003.West Nile virus is primarily a disease of birds that is transmitted by mosquitoes. Infected migratory birds are responsible for the spread of the West Nile virus into a region, with mosquitoes responsible for the spread of the virus to other birds (and other animals and humans). Even though the virus originated in tropical Africa it has adapted to many North American mosquitoes and so far to over 130 species of North American bird, some of which migrate to the Arctic. Mosquito species known to transmit the virus are also found in the American Arctic. Climate has always posed a barrier for insect-borne diseases but climate change and the extremely adaptive nature of the West Nile virus may favor continued northerly expansion. The extent of future expansion and the possibility of transmission to the Arctic remain to be seen. Some northern regions, such as Alaska, have initiated a West Nile virus surveillance program. If the virus does reach Alaska, migratory birds could carry it to the massive population centers of China and South Asia.

Zoonotic diseases are diseases of animals that can also be transmitted to humans. Rabies is a classic example. Rabies infects many wild and domestic animals which may then spread the disease to humans usually from saliva through a bite. In the Arctic, rabies is most often carried by fox and conditions which favor increased fox numbers can lead to rabies epidemics and to human cases. Other arctic zoonotic diseases that could be influenced by climate change include botulism, paralytic shellfish poisoning, tularemia, brucellosis, echinococcus, trichinosis, and cryptosporidium. Botulism spores occur in marine sediments and the intestinal tracts of animals and fish. In Canada and Alaska outbreaks have been associated with seal meat, salmon, and salmon eggs. Also, warmer temperatures are reported to influence traditional fermentation processes (for the preparation of fermented meat – igunaq) which are related to increased cases of botulism in Nunavik. Alaska has established a paralytic shellfish poisoning surveillance program in areas where the algae responsible for the production of the toxin occur. Climate warming may favor the spread of these species to new regions.

The mechanisms by which climate change affects disease agents and their hosts vary. Warmer temperatures may allow species with a low rate of infection, such as brucellosis in caribou or echinococcus in voles, to survive in larger numbers increasing the number of susceptible hosts and infected animals. Disease agents that survive in soil and water may benefit by warmer temperatures.

Climate change may stress host species reducing their resistance and increasing rates of infection. Host species may enter new regions bringing disease agents with them. Continental cross-over from the Americas to Eurasia and from Eurasia to the Americas, as with the West Nile virus and influenza, is also possible and perhaps even more likely with climate change.

Diseases that infect important traditional and economic species can also affect human health. Indigenous groups throughout the circumpolar north have reported a variety of abnormal conditions and diseases in salmon over recent years. Of increasing concern are diseases of farmed salmon or other fish that enter Alaskan waters via ballast waters and then spread to wild salmon. Reduced salmon consumption by indigenous peoples in favor of less healthy foods could lead to increased levels of diabetes, cardiovascular disease, and cancer.

Diseases that could threaten arctic ecosystems and populations following climate change include those that already exist in the Arctic and those moving in from more southerly areas (see Box 15.3). The Arctic could also be a source of disease agents. For example, if West Nile virus reaches Alaska it could easily jump to Asia via established bird migration routes. Diseases of livestock and poultry could also expand through arctic transmission routes. Expansion of disease agents into new environments, in new hosts, and via new vectors encourages new adaptations through natural selection. These could include changes in virulence and resistance and so result in more dangerous strains.

Box 15.3. Zoonotic diseases, climate change, and human health Zoonotic diseases are infectious diseases of animals that can be transmitted to humans. Humans can be infected by these diseases a number of ways. Rabies, tularemia, and many others are transmitted by direct contact with infected animals. Others such as Giardia are shed into the environment and humans are infected following environmental exposure such as consuming contaminated water.The transmission of other diseases may be more complex. Humans are exposed to the West Nile virus from mosquitoes that were infected from birds harboring the virus. Many zoonotic diseases exist in arctic host species. Climate change may influence the spread, proliferation, and transmission of these diseases to humans through a variety of means. Tularemia is a bacterial disease of many mammals including rabbits, muskrats, and beaver, as well as humans and could become an increased threat in stressed animals or by animals expanding into new ranges. Tularemia may cause a variety of symptoms in humans.The pneumonic form has a 30 to 60% fatality rate. Rabies epidemics in the Arctic are linked to the fox and the cyclical increases in fox populations. Climate changes which increase rodent and rabbit populations could be a factor in rabies epidemics. Brucellosis is a bacterial disease of many hoofed animals and carnivores. It can cause a wide variety of symptoms in humans and the fatality rate is around 2% in untreated cases. Bison, caribou, reindeer, foxes, and bears can carry the disease. Climate changes that affect the distribution of these species could increase or decrease the risk from brucellosis. Echinococcus is a tapeworm parasite of animals and humans.The natural cycle involves foxes or dogs and rodents. Humans are an incidental host when they ingest eggs passed by dogs or foxes. The parasite develops invasive destructive cysts in the abdominal cavity and the infection is often fatal. An arctic strain of trichinella occurs in marine mammals such as walrus and accounts for trichinosis outbreaks in some northern regions (e.g., Nunavik). Climate warming that reduces numbers of marine mammals or eliminates them from their current range may decrease the threat and occurrence of human cases of trichinella. Cryptosporidium is a protozoan parasite of many animals and humans. Some recent epidemics involved contamination of community water sources. Climate changes could favor the spread of the parasite to arctic communities that consume untreated surface water.

Influenza is an example of a disease that could be disseminated by arctic bird species to populations in other parts of the world. Bird influenza viruses serve as a genetic reservoir for other animal influenza strains including those that infect humans. Migration can spread these viruses to other species and humans. Influenza is not the stuffy nose, headache, and upset digestive tract that people equate with flu. In each of the 11 epidemics of the last three decades influenza killed 20 000 to 40 000 Americans. The Spanish flu strain of 1918 to 1919 killed more than 20 million people. In the 1998 influenza epidemic in Hong Kong a third of all diagnosed cases died. Fortunately the outbreak was small and did not spread (see Box 15.4).

Box 15.4. Climate change, arctic birds, and influenza Wild birds host many species of virus including influenza. Birds may serve as the source of genetic material or of new influenza strains that could infect humans. The role and mechanism of wild birds in this process is now better understood. Numerous influenza strains are found in wild water birds.The bird–flu relationship is very stable and most infections even with multiple strains cause no symptoms. Many millions of these birds with their associated influenza viruses inhabit the Arctic. Peak numbers in birds and viruses occur in autumn and move south during migration. As the huge flocks move southward influenza strains circulate and recombine within the migrating birds and infect domestic birds and swine along the flyways. Influenza in domestic species brings the viruses closer to humans.The right combination of strains in domestic animals could be the source of a new human strain and a global epidemic. Climate change that favors nesting success, expansion to new ranges, and intermingling of bird species could contribute to this process. The Spanish flu strain of 1918 to 1919 that killed more than 20 million people was thought to have emerged from a swine or bird strain. The Asian flu strain of 1957 and the Hong Kong strain of 1968 may have been the product of human and bird strains.The 1997 to 1998 influenza epidemic in Hong Kong originated in poultry.That epidemic, even though it was small with only 18 confirmed cases, was especially alarming because six of these cases resulted in fatalities.

Extreme events, such as droughts, floods, and storms (see Section 15.3.1 (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)), are also linked to changes in ecological systems resulting in bacterial proliferation and impacts on the availability of safe drinking water. Abnormal rainfall events can trigger mosquito-borne disease outbreaks, flood-related disasters, and depending on existing water infrastructure and systems used in northern communities, contamination of the water supply with human and animal waste. Human health depends on an adequate supply of potable water. If climate change affects the availability of freshwater supply, sanitation systems and the efficiency of local sewage systems will also be affected. Changes in rainfall patterns may also force people to use poorer quality sources of drinking water, potentially increasing the risk of bacterial and other contamination. This is particularly important for those communities in which significant numbers of individuals still rely on traditional sources of drinking water. All these factors could result in an increased incidence of diarrheal diseases.

Summary (15.4.1.3)

Arctic climate change is likely to have profound effects on living things and thus human health, both in northern communities and throughout the world. When traditional food species are affected, dietary patterns may shift to less healthy food choices and diseases such as diabetes, cardiovascular disease, and cancer are likely to increase.

Changes in the traditional food lifestyle are also likely to affect human health through changes in social and cultural activities. Changes that affect commercially important species and so increase or decrease local income can also affect human health. Infectious diseases of plants, animals, and humans are also affected by climatic changes. Owing to the indirect nature of these influences, predictions of their likelihood are not possible; however, the potential impacts on human health related to these changes clearly warrant further attention.

Changes in the physical environment (15.4.2)

Ice and snow (15.4.2.1)

Climate warming scenarios project changes in sea-ice distribution and ice thickness in the Arctic (see Chapter 4 (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)). The direct human health effects of a reduction in ice thickness include injuries and death. Travel over increasingly thin ice for fishing, hunting, or recreation activities becomes increasingly dangerous. Mortality statistics show that accidents cause a significant number of deaths in some Inuit populations. Inuit in northern Canada report a decrease in ice extent and thickness during key traveling and hunting times in some communities.

The indirect health effects related to these changes are associated with marine productivity. Sea ice has a major influence on primary production and the ecology of species such as seals, walrus, and polar bear (see Chapter 9 (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)). Ice algae are a major source of food for a wide range of zooplankton and crustaceans. A reduction in sea-ice extent would reduce the substrate available for the ice algae and so reduce the food source for the ice-associated zooplankton and crustaceans. Greater melting of sea ice would decrease the salinity of the water column and the rate of the vertical flow which brings nutrients up from deeper waters, further reducing the productivity of the phytoplankton. A decrease in primary productivity would affect the crustacean and fish populations upon which seal populations rely. Also, populations of seals and walrus, which require sea ice for breeding and pupping, may decline as ice-covered areas recede. This would affect polar bear populations as seals are their major food supply. Polar bears in Hudson and James Bay are particularly vulnerable in this respect. Some species could be extirpated or become extinct if the Arctic Ocean becomes ice-free for much of the year. Arctic foxes, normally scavenging polar bear kills, may be forced to increase predation on nesting birds in the summer.

Cooling, as is projected for some arctic regions, could have both positive and negative impacts on indigenous food security. During the major cooling of the Arctic around AD 1400 to 1700, the Inuit are thought to have adapted by hunting ringed seals (Phoca hispida) which became more plentiful as the sea ice extended. Similarly, changes in the timing, amount, and composition of snow can affect the health of arctic residents as it influences their abilities to hunt, travel, and access traditional foods at certain times of the year.The changes projected in ice and snow under the various climate change scenarios (see [[Chapter 4 (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)]2]) could have potential impacts on individual and community social health and well-being (see Box 15.5).

…and all of a sudden we had a storm and everyone was lost, years ago you’d get the good snow for [house]s but now, you wouldn’t be able to make one House if you had to. Nain, hunter aged 49

Many villages in the Arctic are connected to other settlements only by sea or air. Because air service to the villages in many regions is irregular, villages are otherwise isolated for two to five weeks every autumn and spring when there is too much ice in the water to go by boat but not enough ice to go by dog sledge or snowmobile. During this period, hunting, fishing, and travel between villages is limited by means other than plane and there is often reduced provision of goods to local stores, and reduced availability of fresh meat or vegetables in some communities. For short periods, the weather can become so stormy that normal everyday activities within the village are difficult.This increased sense of isolation is reported to be associated with increased incidences of interpersonal conflict, depression, and other forms of social stress.

Box 15.5. Climate change and traditional food security Traditional foods collected from the land, sea, lakes, and rivers are important sources of health and well-being to many indigenous communities. Such foods continue to contribute significant amounts of protein to the total diet and help individuals to meet or exceed daily requirements for several vitamins and essential elements. Historically, by eating all animal parts, northern indigenous diets provided the nutrients and essential elements required to sustain life in this harsh climate. Such items are still important today as they contribute, for example, nearly 50% of the weekly protein, iron, and vitamin A intake in Nunavik women under 45 years old and nearly 50% in Labrador Inuit. Components of the Inuit diet, particularly omega-3 fatty acids in fish oils, have been shown to provide protection against arteriosclerosis and ischemic heart disease and some cancers. Also, marine species are the main source of selenium in northern diets; an antioxidant and a known anticarcinogen that may also help protect individuals from mercury toxicity. In addition to the substantial nutritional benefits, traditional foods provide many cultural, social, and economic benefits to individuals and communities. Climate changes may affect the consumption of traditional foods by northern people through a variety of means. Impacts may occur via changes in access to food sources, for example by: a change in the distribution of important food species; the unpredictable nature of weather, as this can influence the possibilities for hunting or fishing; low water levels in lakes and streams, the timing of snow, and ice extent and stability, as these can influence access to hunting locations and key species; and by a shorter winter season and increased snowfall (two effects of a warmer climate), as these may decrease the ability of northern people to hunt and trap. Climate changes may influence the availability and health of traditional food species via: impacts on critical components of their diet (e.g., climate impacts on vegetation may influence caribou health and abundance); impacts on their ability to forage and survive critical seasons (e.g., deeper snow and changes in freezing rain incidents can negatively affect the ability of caribou and reindeer to forage in winter); warming, as this may increase the exposure of some species to insects, pests, and parasites; and via temperature changes as these may influence migration and breeding patterns. The impacts of a decline in the proportion of traditional foods consumed by northern peoples are significant. Shifts away from a traditional diet toward a more western diet, higher in carbohydrates and sugars, are associated with increased levels of cardiovascular diseases, diabetes, vitamin-deficiency disorders, dental cavities, anemia, obesity, and lower resistance to infections. Both climate warming and cooling are as likely to impact on aspects of indigenous food security in the future as they have in the past.

Permafrost (15.4.2.2)

Permafrost is very sensitive to temperature fluctuations. The top layer of permafrost, known as the active layer, thaws in summer and freezes again in winter. A warming of 4 to 5 ºC would cause more than half of the discontinuous permafrost zone in Canada to disappear. Under such a scenario, the boundary between the continuous and discontinuous permafrost zones is expected to shift northward by hundreds of kilometers and the active layer in the discontinuous zone is projected to increase to twice its current depth.The uneven pitted terrain which results can severely affect animal activities and can damage or destroy the ecosystems based on the permafrost. Several impacts of thawing permafrost have already been observed in Alaska.

• Destruction of trees and reduction in areas of boreal forest.
• Expansion of thawed lakes, grasslands, and wetlands.
• Destruction of habitat for caribou and terrestrial birds and mammals.
• Clogging of salmon spawning streams with sediment and debris.

Such impacts could further affect traditional food sources (e.g., caribou, salmon) and the related activities (e.g., hunting, gathering, fishing).

Summary (15.4.2.3)

Through changes in the timing and conditions of ice formation, stability, and break up, the amount and timing of snow, and the stability of critical land (e.g., permafrost) in the regions used by indigenous communities, climate change can result in significant negative impacts on the health of community residents. According to some indigenous communities these changes and their effects are already occurring. Such changes are likely to continue to affect the safety of land- and water-based travel, and availability and access to traditional food species by arctic residents and will thus continue to challenge the health of indigenous communities in the future.

Built environments in the north (15.4.3)

Infrastructure promotes safe and healthy community environments and provides access to health-related services. In northern regions, housing provides protection against harsh environmental conditions and, with adequate ventilation, a healthy living environment. Sanitation facilities are needed to prevent the spread of disease and are increasingly important when population densities are high, or when even small populations are fixed in one location. In small remote communities transportation is often necessary to gain access to healthcare or emergency services. It is likely that climate change will adversely affect infrastructure and housing throughout the Arctic.

Sanitation infrastructure (15.4.3.1)

Unsafe drinking water combined with inadequate sanitation and hygiene is listed sixth in the top ten health risk factors leading to disease, disability, and death worldwide. The provision of high quality water can protect against chemical constituents and waterborne diseases such as hepatitis, gastroenteritis, typhoid, cryptosporidiosis, and giardiasis. Sufficient quantities of water are required for personal hygiene, cleaning, and laundry. Epidemics of otherwise commonly preventable diseases such as hepatitis A, hepatitis B, bronchitis, otitis media (a serious ear infection), impetigo, and meningitis in remote Alaskan communities are often attributed to poor sanitation. Alaskan Native villages with inadequate sanitation systems accounted for more than 72% of 596 reported cases of hepatitis A in Alaska in 1988. The spread of diseases caused by contaminated drinking water or inadequate sanitation is a concern for communities throughout the world.

Sanitation facilities can consist of individual facilities such as septic systems or pit privies (outhouses) or community facilities such as organized haul systems or pipeline networks. The level of health in a community depends on the type of sanitation facilities^[54]. Water hauled by individual residents may be safe at the point of collection, but might become contaminated in the containers used for transport and storage. Closed haul systems (sealed containers) or piped utilities can reduce the potential for contaminating water supplies or human contact with sewage. Sanitation facilities can include different levels of service. In the most basic form, water and wastes are hauled to and from the residence by hand. Providing a community water and wastewater haul system can raise the level of service. Such systems provide greater amounts of water for sanitation purposes and therefore improve the level of community health. Piped utility systems provide the highest level of service and commensurate health benefits. The level of sanitation service provided to arctic communities varies. For example, few Russian arctic communities are served by piped systems, while virtually 100% of Norwegian arctic communities have piped systems or adequate individual facilities. In Canada, Greenland, and the United States, the level of service provided to communities varies substantially from region to region.

In some cases, communities must support utility operation via local user fees. In other cases, the cost of utility operation is supplemented by sources outside the community. In the Arctic, where residents may rely heavily upon subsistence and where economic conditions are often strained, even minor increases in costs may negatively affect utility operation and maintenance.

Water supply systems (15.4.3.2)

Water supply systems include a water source, storage facility, and distribution system. Water sources contaminated by biological, chemical, or mineral constituents may require treatment to render the water supply safe for human consumption. In the United States it is estimated that contaminated drinking water causes more than 900 000 people to become ill and up to 900 to die each year. In 1993, inadequate water treatment in one city caused an outbreak of approximately 403000 illnesses, 440 hospitalizations, and 50 deaths.

Water supplies are required for personal hygiene, cleaning, drinking, and cooking. Owing to the labor involved, when water is hauled individually it is used for drinking and cooking and tends to be used sparingly for hygiene and cleaning. In more sophisticated sanitation systems, water is used to transmit human waste from residences through pipelines or via haul tanks to the point of treatment and/or disposal.

Source

Water sources exist as surface supplies or groundwater wells. The highest quality source with adequate quantity available to the local community is typically used. Sources with significant levels of contaminants require more complex treatment and are undesirable due to increased treatment costs and complexity.

Arctic surface water sources include streams, rivers, lakes, tundra ponds, or man-made impoundments that capture snow and rain. Surface water sources require some form of treatment to ensure that the water is safe for drinking owing to the potential for contamination by pathogens. Groundwater sources generally have less risk of contamination by pathogens.

Naturally occurring organic or inorganic substances can exist in surface water and groundwater supplies. These contaminants are often removed early in the treatment process to avoid the possibility of transforming them – through chemical reactions with disinfectants – into potentially dangerous byproducts.

Although high quality arctic groundwater sources exist, permafrost often restricts the volume these aquifers can produce. Alternatively, there might be a sufficient volume of groundwater to meet a community’s needs but it may be so highly mineralized that it requires sophisticated and costly treatment.

Climate change can cause water sources to become inadequate in volume or unfit in quality in a number of ways. For example:

• Groundwater supplies can be reduced by less frequent precipitation. Intense but less frequent rainstorms limit aquifer recharge by the majority of the water being lost to runoff.
• Drought or short intense storms can affect surface water impoundments. The water supply in small impoundments or lakes can be depleted during long dry periods. Intense storms may cause watersheds to release water too rapidly creating high but short-duration flows and with most of the precipitation being lost to runoff.
• Coastal communities can experience increased levels of salinity, dissolved solids, or other contaminants in groundwater due to a climate change induced sea-level rise. The groundwater may become brackish and unfit for human consumption.
• Flooding of coastal areas by storm surges may become more frequent and severe.Tundra ponds or lakes, located near the coast, can become contaminated by seawater with their water becoming brackish and thus unfit for human consumption.
• Levels of salinity and bromide may increase in river intakes due to rising sea levels. The saline wedge can penetrate farther upstream potentially contaminating river intakes with seawater.
• Intense storms can create high runoff rates that may exceed the design capacity of a water diversion or dam overflow structure. This may result in damage or the complete loss of the facility.
• Thawing permafrost may also damage water diversion or dam structures. As permafrost thaws, structures founded on frozen soil can become unstable. This may compromise the ability of the structure to impound or divert the necessary volumes of water.
• Flooding caused by ice jams in northern rivers often occurs in the spring or early summer when riverbanks are frozen. Flooding of rivers in late summer or autumn is rare. Intense rainstorms that cause flooding when soils are thawed will accelerate riverbank erosion and increase the potential for damage to adjacent structures.
• Northern communities often have limited economies – many based on subsistence.
• Contaminated water sources or damaged intake structures will require repair, modification, or replacement. If resources are not available for repairs or facility replacement, residents may be forced to use an unsafe water supply.

Treatment

Water treatment systems are designed to remove contaminants and inactivate pathogens. Designs differ, and are based on the properties of a water source. Climate change can result in a decrease in the quality of a water source which can then overwhelm the treatment system. The treated water may be safe for consumption but unpalatable due to taste, smell, or color. This can result in residents seeking alternative sources that are untreated and potentially unsafe. Climate change can adversely affect water treatment systems in a number of ways. For example:

• Rising sea levels can contaminate groundwater or surface water sources. A consequent rise in bromide concentrations may increase the formation of dangerous byproducts during disinfection .The process required to treat a water source contaminated by bromide is complex and costly; operation and maintenance of such systems may be prohibitively difficult and expensive for small, remote communities.
• Intense rainstorms can increase turbidity, pathogen, and organic contaminants in a water source. A substantial increase in these contaminants can exceed the ability of a water treatment system to produce safe and palatable water. High levels of suspended material can overwhelm a filtration process and reduce the effectiveness of a disinfectant to inactivate pathogens. Increased levels of organic contaminants can overwhelm a treatment process and increase the formation of dangerous disinfection byproducts.
• Warming weather and longer dry periods can cause more frequent and severe algal blooms in lakes or ponds used as a surface water supply. Algae may clog water treatment filters and so reduce the ability of the system to meet demand. The presence of algae can also increase the formation of disinfection byproducts or cause foul tastes and odors making the water unpalatable.

Fig. 15.11. All-terrain vehicle water haul system, Mekoryuk, Alaska (photo by Mark Baron).

Fig. 15.12. New boardwalk access, Chefornak, Alaska (photo by John Warren).

Fig. 15.13. Aboveground water and sewer utilidor, Selawik, Alaska (photo by John Warren).

Fig. 15.14. Boardwalk damaged by storm surge flooding, Kipnuk, Alaska (photo by Mike Marcaurele).

Distribution

Water distribution in northern communities consists of self-haul, community-haul, or piped utility systems. Self-haul systems require minimal infrastructure because water can be hauled by foot, sled, or small all-terrain vehicle (Fig. 15.11). Community-haul systems use larger haul containers, which require larger vehicles and therefore substantial all-weather access ways. Self-haul and community-haul systems both require convenient access to the bulk treated water storage tank to be viable.

Access roads and boardwalks must be maintained in passable condition for haul systems to operate (Fig. 15.12). The road, bridge, or boardwalk must be structurally sound and capable of supporting relatively heavily loaded vehicles under repetitive daily cycles of operation.

Piped utilities rest on above ground supports or are buried below ground. The more desirable and conventional below ground installation requires thaw-stable soils. When thaw-stable soils do not exist, piped utilities are usually constructed above ground to minimize the potential for thawing of the permafrost and subsequent loss of foundation support for the structure (Fig. 15.13).

When a piped distribution system is used, pipelines must remain sound to ensure the water supply remains safe for human consumption. A breech in a pipeline can allow contamination of the water to occur within the distribution system. In 1989, contamination of the water supply caused by a pipeline breech in Cabool, Missouri, resulted in 243 people becoming ill and four dying.

Often, arctic piped distribution systems continuously circulate water for freeze protection. Loss of water in a distribution system during cold weather can result in loss of circulation and complete freeze failure of the system.

Large structures such as water storage tanks cannot accommodate significant movement of the foundation. Movement of the foundation or loss of foundation support can cause a breech in the shell of a water storage tank, potentially rendering the facility unusable.

Climate change, can adversely affect water distribution systems in many ways. For example:

• Flooding caused by storm surges or heavy rainstorms can damage roads, boardwalks (Fig. 15.14), water storage facilities, and aboveground pipelines. In some areas, floodwaters can include ice, which may substantially increase floodwater damage.
• Roads, boardwalks, pipelines, and water storage facilities can be adversely affected by erosion. Riverbank erosion may accelerate during late season flooding. Coastal communities may experience accelerated erosion along shorelines due to thawing permafrost, severe storms, rising sea levels, or reduced periods of sea-ice cover.
• Frozen seas protect shorelines and reduce the generation of waves created by severe winter storms. Indigenous people report that the extent and duration of sea-ice cover is changing (see Chapters 3 and 6).
• Thawing permafrost can result in the loss of foundation support for aboveground or belowground pipelines, water storage facilities, access roads, or boardwalks. Loss of foundation support for a pipeline can damage the facility and allow contamination of the water supply. Damage to storage facilities, access roads, or boardwalks can render a water distribution system inoperable.

Wastewater systems (15.4.3.3)

Wastewater systems transport human waste from residences, provide treatment, and dispose of effluent. Improper methods of collecting, treating, or disposing of human waste have been attributed to numerous outbreaks of infectious disease. In Sweden, 3600 people became ill at a ski resort through a cross connection between a drinking water reservoir and a sewage pipeline. In Alaska, between 1972 and 1995 more than 7000 cases of hepatitis A were reported to the Epidemiology Section of the Health and Social Services Department. The method of transmission was via the fecal–oral route. Inadequate sewage disposal in many remote communities was cited as the cause.

Fig. 15.15. Honey bucket disposal container, Shishmaref, Alaska (photo by John Warren).

Fig. 15.16. Small sewage haul system, Mekoryuk, Alaska (photo by Mark Baron).

Fig. 15.17. Lagoon waste washed through fence by storm surge flooding, Kipnuk, Alaska (photo by Brian Aklin).

Fig. 15.18. Access road damage by coastal erosion, Shishmaref, Alaska (photo by Tony Weyionanna).

The level of service provided by wastewater collection, treatment, and disposal systems varies throughout the Arctic. In some remote Alaskan villages, residents use small buckets to collect human waste. Buckets are then carried by hand to central disposal points where wastes are dumped into receptacles (Fig. 15.15), or carried directly by the resident to sewage disposal facilities. This is often referred to as a “honey bucket” haul system. A plastic liner is often used to line the bucket and contain the waste. Hauling wastewater from residences by hand is the most unsanitary form of collection and represents the lowest level of wastewater service.

Improved levels of service include pit privies and holding tanks. Pit privies are frequently used when homes are scattered and soil and groundwater conditions are favorable. Holding tanks are used when homes are located in close proximity, or when soil conditions or high groundwater makes septic systems infeasible. Holding tanks are sited at residences and emptied by a community-owned or commercial pumping service. The holding tank size in a particular community is determined by economics and access. Because many villages have narrow roads and boardwalks, large vehicle access is limited and holding tank volumes are typically small (Fig. 15.16). Thus, the amount of water available for personal hygiene and cleaning is minimal. Piped utilities provide the highest level of service. Flush toilets are normally used in piped systems, and water supplies and wastewater removal systems can provide ample water for personal hygiene, cleaning, laundry, or other sanitation needs.

Collection

Wastewater collection systems are designed to minimize the potential for human contact with sewage. Disease transmission can occur in populations where collection systems are inadequate and contact with wastewater is not controlled. Failed collection systems can discharge human waste to the environment, contaminate water supplies, and transmit disease via human contact. Many of the effects of climate change on water distribution systems also apply to wastewater collection infrastructure. Roads must remain in passable condition throughout the year for haul systems to operate; pipeline integrity must be maintained for piped wastewater collection systems to function properly.

Treatment and disposal

Wastewater treatment for small remote arctic communities is generally limited to simple systems. Mechanical treatment methods, such as aeration, are not typically used due to cost and complexity of operation.

In the Arctic, individual wastewater treatment facilities include pit privies and septic systems. Community facilities typically include earthen lagoons, tundra ponds, septic tanks with ocean outfalls, and septic tanks with drainfields. When communities are located near water and favorable soils exist, drainfields are placed within the thaw bulbs of rivers or along seashores.

Wastewater treatment and disposal systems are designed to ensure wastewater remains separate from the water supply, human contact with waste does not occur, and the potential for vector transport is limited.

Climate change can adversely affect wastewater treatment and disposal systems in a number of ways. For example:

• Flooding caused by storm surges or swollen rivers can adversely affect wastewater lagoons, tundra ponds, bunkers, pit privies, or septic systems. Floodwaters may enter these facilities and spread partially treated waste throughout communities or into water supplies (Fig. 15.17).
• Riverbank or shoreline erosion can damage wastewater facilities located along seashores or within the thaw bulb of a river. Erosion can also intercept wastewater lagoons and tundra ponds.
• The warming of ice-rich permafrost beneath lagoon dikes can cause the loss of structural support. As dikes settle, a breech may occur resulting in the discharge of human waste into the environment. In such circumstances, increased maintenance – at a minimum – is required to sustain operational wastewater volumes and treatment efficiencies.
• However, warming weather and longer summers can also increase biological activity in wastewater lagoons and natural tundra ponds used for treatment. This increase in biological activity can improve treatment efficiencies resulting in increased treatment capacity and potentially delaying the need to expand or replace facilities due to community growth.

Solid waste systems (15.4.3.4)

Solid waste collection and disposal in the Arctic is performed with relatively conventional methods. Recycling, incineration, and baling facilities are rare and generally limited to larger communities. Collection in very small communities is typically by self-haul. Larger communities often use community-haul systems, which are preferred because wastes are more likely to be discarded in proper locations.

Solid waste disposal sites in the Arctic are generally frozen. Landfill wastes are often inadvertently mixed with snow due to winter operations and later covered with soil. Therefore wastes remain stable as long as materials remain frozen.

Many of the effects of climate change on water and wastewater systems also apply to solid waste collection infrastructure. Landfill access routes must remain passable for collection and disposal to occur. Flooding and erosion of solid waste landfills can spread waste, contaminate water supplies, and transmit disease through human contact. As frozen solid waste materials thaw, they can release contaminants into the environment through runoff.

Building structures (15.4.3.5)

Critical requirements for housing in the Arctic include efficient and dependable heating and adequate ventilation. Northern economies are often limited and house are typically small, and so less costly to construct and heat. Such conditions may result in overcrowding. Also, building envelopes are usually tightly constructed to reduce heat loss and minimize heating costs. This combination of overcrowding and poor ventilation can lead to poor indoor air quality and potentially unhealthy living conditions.

Indoor air pollutants dangerous to health include mold, radon, tobacco smoke, carbon monoxide, and chemical emissions from household products and furnishings. Adverse short-term health effects of poor indoor air include asthma, hypersensitivity pneumonitis, and humidifier fever. Long-term health effects include respiratory disease, heart disease, and cancer.

Climate change can result in the destruction of housing via flooding and erosion, through loss of foundational support due to thawing permafrost, or by severe storm damage. Lost housing can cause further overcrowding, respiratory illness, and mental stress in small communities.

Health service buildings within remote communities offer quick access to basic health care and emergency services. When these structures are damaged by climate change, community health care is disrupted.

Transportation infrastructure

Transportation infrastructure provides access to health services located outside remote communities. Emergency transport of individuals from northern communities, usually by medical evacuation, to sites where comprehensive health services exist is critical. Infrastructure such as airstrips, roads (Fig. 15.18), and docks can be damaged by climate change. This damage can limit access to critical health care and emergency services.

Summary (15.4.3.6)

The potential effects of climate change include increased variability in precipitation, reductions in the extent of sea ice, and climate warming and cooling.These changes can increase the frequency and severity of river and coastal flooding and erosion, drought, and degradation of permafrost. Such changes are very likely to impact on arctic infrastructure and housing.

Water sources may be subject to saltwater intrusion and increased contaminant levels, which may overwhelm treatment processes and jeopardize the safety of drinking water supplies. The quantities of water available for basic hygiene can become limited due to drought and damaged infrastructure. The incidence of disease caused by contact with human waste can increase when sewage is spread by flooding, damaged infrastructure, or inadequate hygiene. Damaged infrastructure increases repair costs and further stresses fragile arctic economies.

The positive effects of climate change include reduced heating costs for buildings and pipelines. Treatment efficiencies in wastewater lagoons may also improve due to warmer water temperatures resulting from longer periods of warm weather.This increased efficiency may delay the need to expand natural wastewater treatment systems as local populations grow. As an example, Box 15.6 summarizes the links between infrastructure, climate, and public health in Shishmaref, Alaska.

Box 15.6. Infrastructure, climate and public health: Shishmaref, Alaska Recent studies indicate reductions in sea-ice thickness and shorter periods of sea-ice cover in Alaska.These climatic changes have increased shoreline erosion of Shishmaref, an Iñupiat village of 560 people located on Sarichef Island in the Chukchi Sea. Archaeological finds indicate centuries of human habitation in Shishmaref. Villagers state that erosion has been accelerated by soils no longer frozen, limited sea-ice cover, and increasingly violent weather. During the winters of 2000/01 and 2002/03, erosion caused the bluff line to recede more than 12 meters, destroying structures and forcing other homes to be moved. Several other communities in the region, including Kivalina, Wainwright, and Barrow, face similar challenges related to coastal erosion. Shishmaref uses two different haul systems for water and wastewater transport. One system consists of small water and sewage holding tanks within homes that are filled and emptied by small motorized haul vehicles operated by the community. Remaining residents haul their own water and use a community-operated honey bucket haul system for waste disposal. The community’s water source is a rain/snow catchment impoundment located near sea level. Water is treated by a simple unaided sand filtration system with activated carbon enhancement. Recent storms in Shishmaref have prompted evacuations, washed away a number of boats used for subsistence, and destroyed buildings and roads. Erosion is threatening the sewage lagoon and the village sanitation system, and local officials are concerned that seawater has contaminated the community’s water source (Anchorage Daily News, November 23, 2003, Severe Storms Pound Shishmaref). Coastal erosion damage, Shishmaref, Alaska (photo by Curtis Nayokpuk) The destruction, property loss, threatened sanitation systems, and realization that the community will ultimately have to be moved is creating significant stress within the community. In summary, climate-related changes in Shishmaref will have both short-term and long-term effects on human health.

Contaminants (15.4.4)

Human and ecosystem health in the Arctic is affected by the accumulation of heavy metals and biologically persistent man-made compounds of industrial and agricultural origin, known as persistent organic pollutants (POPs).These contaminants are mostly generated at lower latitudes and transported by various natural mechanisms (termed contaminant pathways) to the Arctic. They then enter the arctic food chain, and are ultimately consumed by human residents who are often highly dependent on wildlife for food.

Human health effects (15.4.4.1)

Health effects of chronic low-level exposure to POPs and heavy metals, such as lead, mercury, and cadmium, are, in general, incompletely understood. An assessment on this topic was published recently by AMAP. Several points require emphasizing:

• in terms of low-level chronic food-borne exposure, pregnant women, the developing fetus, and the developing infant are the most sensitive stages of human life;
• the exposure is to a mixture, never a single compound, making assignment of cause and effect very difficult;
• toxicological models and wildlife studies suggest that neurodevelopment, growth, immunological development, and endocrine function are the most likely targets for effects from exposure;
• sensitivity to these compounds varies widely in wildlife and laboratory species, and is not always useful in predicting the toxicity of tissue levels in humans;
• the developmental effects potentially attributable in human infants exposed to these compounds can also be caused by many other exposures, confounding study results;
• arctic communities are often small, making statistically significant sampling difficult;
• long-term studies are further complicated by difficult access to remote communities for follow-up; and
• the arctic marine subsistence diet is rich in antioxidants such as selenium, omega-3 fatty acids, and other micronutrients. Selenium has the potential to mitigate the toxicity of mercury.

Major transport pathways (15.4.4.2)

Major contaminant transport pathways include winds, ocean currents, and river outflow, all of which are affected by climate. Important mechanisms within the Arctic also affect contaminant transfer, such as surface ice movement, thawing of permafrost and glaciers, season length, changes in freshwater lakes, and the partitioning of chemical compounds between gas, liquid, and solid phases. Migratory species, which spend significant parts of their life cycle at lower latitudes, can accumulate these contaminants and bring them into the Arctic. Also, increased levels of human activity in the Arctic, including maritime transport, represent a potential mechanism for contaminant transport and release. Each of these mechanisms is reviewed in this section within the context of potential impacts on human health. It must be understood that all these pathways, and their impact on transport, have the same limitations as climate models: (1) it is difficult to detect trends, due to short instrumental records, and (2) linking change in the various pathways to climate change, and predicting their effect on each other is poorly understood in many cases. A more complete discussion on this topic was published recently by AMAP.

Season length

The length of time air masses remain at, or above, critical temperatures influences the extent to which an organic contaminant can volatilize and remain easily within the gas phase, or attached to airborne particles. Air mass movements can be rapid and cover long distances. With the projected increase in season length, contaminant movement could significantly increase, both into and out of the Arctic. Season length, by its effect on ice melt, the active layer of permafrost, periods of ice-free river flow, and longer growing periods has the major mediating influence on contaminant movement into, out of, and within the Arctic.

Atmospheric transport

Atmospheric circulation in the Northern Hemisphere is influenced by atmospheric pressure. Established patterns of pressure variation, including the Northern Hemisphere Annual mode, often referred to as the Arctic Oscillation(AO) have major influence on surface wind.

The AO, while a major influence on arctic climate, is thought to account for only 20% of variance in atmospheric pressure (see Chapter 2). Short (5- to 7-year) and longer term (50- to 80-year) variations in the sea- level atmospheric pressure fields, possible contributions from greenhouse gas warming, and the lack of long-term instrumental records make interpretation of AO variations since the 1960s difficult. Major winds into the Arctic fluctuate in intensity, duration, and to some extent, direction based on atmospheric pressure fields.

Various forms of precipitation, including snow and rain, act to remove contaminants from transporting air masses, and add them to land, surface ice, snow, and surface water. Increasing precipitation as a result of climate change could result in increased levels of contaminant deposition.

Winds are the major source of mercury to the Arctic, mostly in its metallic gaseous form. Loss of ozone in the upper layers of the atmosphere allows increased levels of UV-B radiation to reach the earth’s surface in the Arctic. This initiates a complex mercury–halide interaction changing mercury to reactive gaseous mercury, which is easily removed from the atmosphere and taken up by the ecosystem in the early spring during the intense growth period. This atmospheric removal of mercury, termed a mercury depletion event, is most prominent during the period of “polar sunrise” in spring. The combination of possibly increased transport of gaseous mercury, less atmospheric ozone to block UV-B radiation, earlier ice-free periods along the Arctic Ocean shoreline, and abundant supplies of bromine and chlorine salts, could impact upon food web and human mercury accumulation. Extreme events might also increase rates of transport and contaminant deposition (see Fig. 8.22).

Ocean currents

Contaminant transport by ocean currents occurs primarily at the surface and the largest input is from the North Atlantic between Greenland and Norway, with a smaller input from the North Pacific via the Bering Sea. A significant input from freshwater occurs via rivers entering the Arctic Ocean. The AO and season length influence these inflows.

A large volume of water and ice exits the Arctic Ocean via the Canadian Archipelago, carrying with it suspended and dissolved contaminants brought into the Arctic by wind, rivers, and ocean currents. Climatic conditions favoring increased ocean current transport to the Arctic Ocean would potentially expose all human residents, but might expose those of the Canadian Archipelago, as well as those of West Greenland and eastern Labrador, to higher levels.

Sea ice and glaciers

Ice, in the form of sea ice or land-based glaciers, is capable of storing contaminants deposited by wind. As climate warming causes melting, the ice releases contaminants, either by volatilization or by release of particulate- associated contaminants into surface water, where further transport or entry into the food chain occurs.

Exposure of Arctic Ocean surface water, as a result of decreasing ice cover, could increase the movement of contaminants such as hexachlorocyclohexanes (HCHs) and toxaphene into the atmosphere, speeding movement within or out of the Arctic.

Sea ice can also transport contaminants by other means, particularly by accumulating contaminants in sediment, from grounding on shallow coastal shelves, particularly where rivers enter the Arctic basin. Sediment-rich shallow water can also be incorporated into sea ice by freezing as surface ice is formed. The contaminant- bearing ice can then follow established circulation patterns in the Arctic Ocean, influenced by wind and surface air temperature, releasing contaminant-containing sediment as it melts. While the components of this cycle are well described, climate change could affect any particular step, regionally or throughout the Arctic Ocean, with unpredictable effects on contaminant transport and human health.

Rivers and lakes

River flow into the Arctic Ocean will increase if, as projected by the ACIA-designated climate models, there is an increase in precipitation and the length of the ice-free period for much of the Arctic and subarctic. This will promote increased river transport of contaminants from industrial and agricultural sources further south.

Arctic lakes are thought to have functioned as temporary storage for contaminants deposited in snow during the winter, with rapid runoff removal in spring. It is possible that an earlier melt, increased contaminant inputs to the lake water, and an earlier onset of spring growth in the lake ecosystem could result in greater amounts of contaminants being incorporated into the ecosystem, and thus into organisms consumed by humans.

Permafrost

Permafrost underlies much of the Arctic. In regions of discontinuous permafrost, contaminants deposited onto the surface by wind, rain, and snow are released during thawing and mobilized into active biological systems or into runoff, eventually draining into lakes, rivers, and the ocean. Permafrost also acts as a containment mechanism for man-made waste sites, such as landfills, sewage lagoons, mine tailings, and dumpsites. Increasing season length and surface air temperatures could allow contaminants to migrate through active permafrost layers to surface water sources used by humans and wildlife. Entry into runoff during periods of increased rainfall is also a possibility. The overall effect of permafrost thawing is likely to be increased contaminant exposure by a variety of mechanisms, and represents a “new” transport pathway.

Wildlife

Pacific salmon (Oncorhynchus spp.) spawn and die in freshwater streams and lakes. Contaminants accumulated by a salmon during that part of its lifecycle spent in the North Pacific are deposited into the local freshwater ecosystem where it dies. Over the past decades, as warming has occurred, Pacific salmon species have gradually extended their range north into the Arctic, adding contaminant loads to the predators and local biomass where they spawn and die. The magnitude of this input, for some freshwater systems, has been shown to exceed the input from atmospheric pathways^[86]. Some contaminants, which are present at higher concentrations in the North Pacific than the Arctic, notably b-HCH, could thus increase in local arctic freshwater systems to levels higher than at present, so increasing the potential for human exposure and possible health effects.

Humans

Potentially, the greatest impact from human activities is from increased maritime traffic during ice-free periods with the sudden catastrophic release of hazardous materials into the local, regional, and eventually circumpolar environment. The possible increase in extreme weather events could increase the likelihood of such an event.

Summary (15.4.4.3)

The transport mechanisms and pathways for contaminants in the Arctic are incompletely understood. Time trends are not available for the concentrations of most contaminants in most media, and instrumental records for major forcing factors are equally sparse. Models that link contaminant movement to climate events do not yet exist. All components of all contaminant pathways are affected by climate. The degree of uncertainty in the climate processes precludes prediction based on current climate models, but makes a powerful case for further research, as well as environmental, wildlife, and human health monitoring.

Monitoring and research on contaminant health effects in arctic residents and ecosystems is ongoing, and must now be linked to systematic research on contaminant movements into, and out of the Arctic. A warming climate in the Arctic could offer a variety of new economic opportunities to arctic residents, including increased maritime activity. International efforts should continue at preventing massive contaminant spills in the Arctic: such spills could be the most damaging contaminant event for local and regional ecosystems and residents.

Chapter 15: Human Health
15.1. Introduction (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)
15.2. Socio-cultural conditions, health status, and demography
15.3. Potential impacts of direct mechanisms of climate change on human health
15.4. Potential impacts of indirect mechanisms of climate change on human health
15.5. Environmental change and social, cultural, and mental health
15.6. Developing a community response to climate change and health
15.7. Conclusions and recommendations (Potential impacts of indirect mechanisms of climate change on human health in the Arctic) (Potential impacts of indirect mechanisms of climate change on human health in the Arctic)

References

1. {{note|54}Ibid.
2. ^[87]Ewald, G., P. Larsson, H. Linge, L. Okla and N. Szarzi, 1998. Bio-transport of organic pollutants to an inland Alaska lake by migrating Sockeye salmon (Oncorhynchus nerka). Arctic, 51:40–47.

Citation

Committee, I. (2012). Potential impacts of indirect mechanisms of climate change on human health in the Arctic. Retrieved from http://editors.eol.org/eoearth/wiki/Potential_impacts_of_indirect_mechanisms_of_climate_change_on_human_health_in_the_Arctic