Chapter 2. Climate Variability and Change in the Canadian Eastern Subarctic IRIS Region (Nunavik and Nunatsiavut)
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Chapter 2. Climate variability and change in the Canadian Eastern Subarctic IRIS region (Nunavik and Nunatsiavut) Lead authors Ross Brown1,2 and Mickaël Lemay3 1Environment Canada, 2Ouranos, 3ArcticNet, Centre d’études nordiques, Université Laval Contributing authors M. Allard, N.E. Barrand, C. Barrette, Y. Bégin, T. Bell, M. Bernier, S. Bleau, D. Chaumont, Y. Dibike, A. Frigon, P. Leblanc, D. Paquin, M. J. Sharp and R. Way Special Acknowledgements Ouranos played an important role in the development of this IRIS assessment by providing output from the Canadian Regional Climate Model as well as climate-related expertise to the scientists working in the diverse fields covered in the assessment. This information is an essential building block for the assessment and development of local and regional adaptation strategies. Daniel Caya in particular is acknowledged for providing detailed and constructive review comments of the draft chapter. CONSORTIUM ON REGIONAL CLIMATOLOGY AND ADAPTATION TO CLIMATE CHANGE 57 CLIMATE VARIABILITY AND CHANGE Chapter 2 Key messages * Paleoclimate reconstructions indicate the climate of the Nunavik-Nunatsiavut IRIS region has experi- enced a long-term cooling trend over the past approximately 3000 years, with major climate fluctua- tions in the Medieval Warm Period (warming) and Little Ice Age (cooling). The climate began to warm during the 20th Century with a marked warming pulse after 1993 that has triggered a rapid response in the environment, especially the cryosphere (snow and ice cover, permafrost, and glaciers). Den- droecological evidence and climate observations show evidence of long term significant increases in precipitation over the region. * There is some uncertainty in the timing of the recent period of warming. Satellite snow cover data and vegetation monitoring suggest the climate has been changing for at least 30-40 years while air temperature observations from coastal sites show warming did not occur until 1993. These differences may reflect different climate regimes between coastal areas and inland areas and/or different response processes. * The cryosphere (solid precipitation, snow and ice cover, glaciers and permafrost) is responding very rapidly to recent warming. Snow and ice cover are forming later and melting earlier with annual losses of snow and ice cover duration on the order of 0.5 to 1.0 days/yr. Warming of permafrost by 2°C has resulted in a dramatic increase in the number of thermokarst lakes and active layer detachments, and glaciers in the Torngat Mountains lost ~20% of their area between 2005 and 2007. Traditional know- ledge indicates that these changes are outside the envelope of previous community experience. * Climate change projections for the 2041-2070 period (compared to the 1971-2000 period) indicate warmer temperatures and increased precipitation over the region. The largest changes are projected to occur in the winter season with the spatial pattern of projected changes typically exhibiting a NW-SE gradient with the largest changes over the north-western part of Nunavik. The results suggest a shorten- ing of the snow and ice cover season by 3-4 weeks, an increase in growing season length by 2-3 weeks with up to 50% more growing degree days, and increases in annual precipitation of 15-25% with a larger fraction of annual precipitation falling as rainfall. * The climate of the Nunavik-Nunatsiavut IRIS region is strongly influenced by variability in atmospher- ic and oceanic circulation at annual to multi-decadal scales. In particular, the year-to-year variability of the climate of Nunatsiavut is closely linked to the North Atlantic Oscillation. For some variables such as local precipitation, the internal climate variability will likely dominate any climate change signal over the next 30-50 year time period. * Reliable and sustainable environmental monitoring and prediction systems are essential to supporting decision making and adaptation in the Nunavik-Nunatsiavut IRIS region. The merging of traditional and scientific knowledge in community-based monitoring initiatives appears to be a useful framework for improved monitoring and understanding of changing environmental conditions with the relevant connec- tions to ensure that new information is translated into enhanced safety and improved decision making. 58 Chapter 2 CLIMATE VARIABILITY AND CHANGE 2.1 Introduction of the region and its variability and change; Section 2.3 presents a general description of the main drivers of the The purpose of this chapter is to highlight the key char- climate of Nunavik and Nunatsiavut with sub-sections acteristics of the climate of Nunavik and Nunatsiavut that providing more detailed information on variability and are important for natural systems, ecosystem services and change in important components of the climate system human activities, and present scenarios of projected chan- over the period of available historical and paleoclimat- ges in key climate variables and indicators that may occur ic data; Section 2.4 presents a summary of the climate over the next ~50 years. Climate is the key driver of pro- change projections for 2050 provided in detail in Appen- cesses such as snow and ice formation, frozen ground, dix A at the end of this Chapter. The Chapter ends with a spring thaw, water cycling, and plant growth that define summary and conclusions in Section 2.5 that are encapsu- the environment and sustain ecosystem services (see ex- lated in the “key messages” shown above. amples in Table 1). In this sense, climate represents a “re- source” that influences the value and the quality of the en- vironment, but it also entails management of “risks” par- 2.2 Climate observations and ticularly in the context of a changing climate (“Climate as information Resource, Climate as Risk”, Stehr and vonStorch 2009). There are a number of challenges to characterizing the The organization of the Chapter is as follows: Section 2.2 climate of Nunavik and Nunatsiavut, foremost of which provides an overview of the sources (and limitations) of is the uneven spatial and temporal coverage of climate the information available for characterizing the climate observations. Daily climate observations of temperature Table 1. Examples of climate sensitivities identified in this IRIS assessment eport.r Variable/Activity Climate Sensitivity The amount, timing, temperature and chemical and biological Freshwater Resources (Chapter 4) properties of freshwater are sensitive to air temperature and to precipitation amount and type. Winter hunting activities are particularly sensitive to snow and Traditional Foods (Chapter 5) ice conditions. A projected shortening of the ice and snow cover seasons will affect both availability and access to fresh meat. Projected warming and increased winter snow accumulations contribute to permafrost thawing, a deepening of the active layer, Infrastructure (Chapter 6) and a host of related phenomena such as active layer detachments and enhanced erosion of coastal areas, all of which pose additional challenges for northern infrastructure. Fish abundance and habitat are sensitive to ice cover, water Arctic Charr (Chapter 7) temperature and water quality. Warming and changes in precipitation regimes are contributing Vegetation Dynamics (Chapter 8) to an increase in woody vegetation and a northward and up-slope expansion of treelines. Caribou are sensitive to ice cover (migration routes), rain-on- snow events (affect access to winter forage), summer snow cover Caribou Dynamics (Chapter 9) (residual snow patches reduce insect harassment) and the timing of vegetation green-up. 59 CLIMATE VARIABILITY AND CHANGE Chapter 2 and precipitation are available for most communities but temperature reconstructions from tree rings (e.g. Jacoby the length and period of observations are quite variable. et al. 1988), reconstruction of past climates from analysis For example, only Kuujjuaq, Goose Bay and Cartwright of fossil chironomids and pollen (e.g. Kerwin et al. 2004, have continuous daily climate data available from pre- Fallu et al. 2005) and reconstruction of information on 1950 to date; many of the other stations stopped reporting snow depth and water levels from dendroecological an- in the early 1990s or started reporting in the 1980s. The alysis of tree morphology and ice abrasion (e.g. Lavoie climate observing network is also almost completely co- and Payette 1992, Bégin and Payette 1988, Lemay and located with coastal communities and may not necessarily Bégin 2008). reflect what is going on further inland. The main locations of the climate stations used in this Chapter are Inukjuaq, Traditional knowledge is another useful source of infor- Kuujjuarapik, Kuujjuaq and Schefferville in Nunavik, mation for documenting anomalous events and trends, par- and Goose Bay, Cartwright, Makkovik, and Nain in Nu- ticularly ice and snow cover, that have major impacts on natsiavut (for location map see Figure 1, Chapter 1). hunting and transportation. While this information is not quantitative, it provides a local-scale record of environ- Climate data are also subject to random and systematic mental change. For example, Elders of Quaqtaq, Umiujaq errors related to observers, instrumentation, and changes and Kuujjuaq report that since the 1980s ice forms later in measurement site and observing procedures. For ex- and melts earlier, rain is more frequent, there is less snow- ample, precipitation is one of the more difficult climate fall and wind patterns have changed in Hudson Bay and variables