Building damaged due to permafrost thawing in Russia
Projected increases in permafrost temperatures and in the depth of the active layer are very likely to cause settling, and to present significant engineering challenges to infrastructure such as roads, buildings, and industrial facilities. Remedial measures are likely to be required in many cases to avoid structural failure and its consequences. The projected rate of warming and its effects will need to be taken into account in the design of all new construction, requiring deeper pilings, thicker insulation, and other measures that will increase costs.
In some areas, interactions between climate warming and inadequate engineering are causing problems. The weight of buildings on permafrost is an important factor; while many heavy, multi-story buildings of northern Russia have suffered structural failures, the lighter-weight buildings of North America have had fewer such problems as permafrost has warmed. Continuous repair and maintenance is also required for buildings on permafrost, a lesson learned because many of the buildings that failed were not properly maintained. The problems now being experienced in Russia can be expected to occur elsewhere in the Arctic if buildings are not designed and maintained to accommodate future warming.
Structural failures of transportation and industrial infrastructure are also becoming more common as a result of permafrost thawing in northern Russia. Many sub-grade railway lines are deformed, airport runways in several cities are in an emergency state, and oil and gas pipelines are breaking, causing accidents and spills that have removed large amounts of land from use because of soil contamination. Future concerns include a weakening of the walls of open pit mines, and pollutant effects from large mine tailing disposal facilities as frozen layers thaw, releasing excess water and contaminants into groundwater.
The effects of permafrost thawing on infrastructure in this century will be more serious and immediate in the discontinuous permafrost zone than in the continuous zone. Because complete thawing is expected to take centuries, and benefits (such as easier construction in totally thawed ground) would occur only after that time, the consequences for the next 100 years or so will be primarily negative (that is, destructive and costly).
Yakutsk, Russia Experiences Infrastructure Failure as Permafrost Thaws In Yakutsk, a Russian city built over permafrost in central Siberia, more than 300 buildings have been damaged by thaw-induced settlement. The infrastructure affected by collapsing ground due to permafrost thaw includes several large residential buildings, a power station, and a runway at Yakutsk airport. Some ascribe a large proportion of the city’s recent problems to climatic warming, though others believe that better construction practices and maintenance could have prevented much of the trouble.
Research on the impacts of warming on infrastructure indicates that even small increases in air temperature substantially affect building stability, and that the safety of building foundations decreases sharply with increasing temperature. This effect can result in a significant decrease in the lifetime of structures as well as the potential failure of structures.
As global warming continues, detrimental impacts on infrastructure throughout the permafrost regions can be expected. Many of these impacts might be anticipated, allowing structures to be re-designed and re-engineered to withstand additional pressures under changing climatic conditions. This will certainly incur costs, but can avoid the dramatic infrastructure failures being experienced in Yakutsk and elsewhere in the Arctic.
Floods and Slides
Another set of climate-related problems for arctic infrastructure involves floods, mudslides, rockslides, and avalanches. These events are closely associated with heavy precipitation events, high river runoff, and elevated temperatures, all of which are projected to occur more frequently as climate change progresses. Soil slopes are also made less stable by thawing permafrost, and this is expected to result in more slides. Some transportation routes to markets are sensitive to the types of weather events that are expected to increase as climate continues to warm. Protecting or improving these routes will be required.
Impacts of Thawing Permafrost on Natural Ecosystems
Important two-way interactions exist between climate-induced changes in permafrost and vegetation. As permafrost thaws, it affects the vegetation that grows on the surface. At the same time, the vegetation, which is also experiencing impacts due to climate change, plays an important role in insulating and maintaining the permafrost. For example, forests help sustain permafrost because the tree canopy intercepts the sun’s heat and the thick layer of moss on the surface insulates the ground. Thus, the projected increase in forest disturbances such as fire and insect infestations can be expected to lead to further degradation of permafrost, in addition to what is projected to result directly from rising temperatures.
In some northern forests, certain tree species (notably black spruce) utilize the ice-rich permafrost to maintain the structure of the soil in which they are rooted. Thawing of this frozen ground can lead to severe leaning of trees (sometimes referred to as “drunken forest”) or complete toppling of trees. Thus, even if a longer, warmer growing season might otherwise promote growth of these trees, thawing permafrost can undermine or destroy the root zone due to uneven settling of the ground surface, leading instead to tree collapse and death. In addition, where the ground surface subsides due to permafrost thaw, even if the trees do not fall over, these sites often become the new lowest points on the landscape. At least seasonally, these places fill with water, drowning the trees.
The potential for many shallow streams, ponds, and wetlands in the Arctic to dry out under a warming climate is increased by the loss of permafrost. As permafrost thaws, ponds connect with the groundwater system. They are thus likely to drain if losses due to downward percolation and evaporation are greater than re-supply by spring snowmelt and summer precipitation. Patchy arctic wetlands are particularly sensitive to permafrost degradation that links surface waters to groundwater. Those along the southern limit of permafrost, where increases in temperature are most likely to eliminate the relatively warm permafrost, are at the highest risk of drainage. Indigenous people in Nunavut (eastern arctic Canada) have observed recently that there has been increased drying of rivers, swamps, and bogs, to the extent that access to traditional hunting grounds and, in some instances, migration of fish, have been impaired. There is also a high risk of catastrophic drainage of permafrost-based lakes, such as those found along the western arctic coast of Canada.
In other places, warming of surface permafrost above frozen ground and associated collapsing of ground surfaces could increase the formation of wetlands, ponds, and drainage networks, particularly in areas characterized by heavy concentrations of ground ice. Such thawing, however, would also lead to dramatic increases in sediment being deposited into rivers, lakes, deltas, and coastal marine environments, resulting in significant impacts to aquatic life in these bodies of water.
Changes to the water-balance of northern wetlands are especially important because most wetlands in permafrost regions are peatlands, which may absorb or emit carbon (as carbon dioxide or methane) depending on the depth of the water table. There are many uncertainties in projections of these changes. One analysis suggests that an increase in temperature of 4˚C would reduce water storage in northern peatlands, even with a small and persistent increase in precipitation, causing peatlands to switch from emitting carbon dioxide to the atmosphere to absorbing it. It is also possible that the opposite could occur, whereby warming and drying could cause the rate of decomposition of organic matter to increase faster than the rate of photosynthesis, resulting in an increase in carbon dioxide emissions. A combination of temperature increase and elevated groundwater levels could result in increased methane emissions. Projections based on doubling of pre-industrial carbon dioxide levels, anticipated to occur around the middle of this century, suggest a major northward shift (by 200-300 kilometers) of the southern boundary of these peatlands in western Canada and a significant change in their structure and vegetation all the way to the coast.