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Cold Snaps and Climate Change

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6 min

Summary

Periodic bouts of extreme cold do not invalidate or weaken the overwhelming scientific evidence that human activities are warming the Earth. In fact, extreme cold temperatures are getting warmer in Canada.  When averaged nationwide, coldest annual temperatures warmed by 3.3°C between 1948 and 2016.

The Essentials

  • There is a clear scientific consensus that human activities – primarily the burning of fossil fuels – are causing the Earth to warm, and that the Arctic is warming two to three times as fast as the globe as a whole.1,2,3,4
  • This overarching warming trend has been punctuated periodically by episodes of cold winter weather (“cold snaps”) in northern temperate regions, including North America and Eurasia.5
  • It is important to remember that any single weather event is not representative of what is happening with the climate. Globally, heat waves increasingly outnumber cold snaps.
  • The vast majority of these cold snaps are not setting new records for coldness. Nonetheless, these cold snaps bring temperatures that are significantly colder than average for the time of year, and they can have serious effects on human health, transportation systems, and energy consumption.
  • It is important to consider occasional cold snaps in context with longer-term trends. In Canada, long-term observations show that cold extremes are declining.4
  • While cold snaps continue to occur, extreme cold temperatures in Canada have become less cold. Averaged across the country, the annual lowest daily minimum temperature* increased by more than 3°C between 1948 and 2016, with the strongest warming in the west.4 Only about 0.5°C of this increase can be related to natural internal climate variability, while the human caused component could be as much as 2.8°C.4
  • In most places in the world, it is virtually certain that there will be fewer cold temperature extremes as global average temperatures increase.6 This will also be the case for Canada.4
  • Scientists do not know for certain which factors contribute most to periodic cold snaps. Research in this area is ongoing. Some science suggests that changes in the tropics could be an important factor.7 Other research has suggested that climate-change-related Arctic warming may be key.1,8,9,10
  • Recent changes in the Arctic may be influencing mid-latitude weather, and potentially impacting millions of people. However, there is currently only low to medium confidence in the nature of the linkages between Arctic conditions and weather in this region.1 For example, there is some evidence of an increase in the frequency of weak polar vortex events, in which masses of cold Arctic air can push equatorward, but studies have not shown increases in the number of mid-latitude cold events, either in observations or in climate model projections of future conditions.1 Research to better understand the influence of the Arctic on extreme weather is ongoing.

* Daily minimum temperature corresponds to the lowest temperature recorded in a 24-hour period. The majority of the daily minimum temperatures recorded in Canada occur during the night-time hours rather than during the daytime.

Warming, not increasing cold, is of greatest concern

Although cold snaps have impacts on our activities during their occurrence, the overall warming conditions in Canada are generally of more concern. Warming temperatures, particularly in winter in northern Canada, are already having impacts.11

  • The length of the snow cover season is decreasing, with later onset in the fall and earlier spring melt.
  • Perennial sea ice is being replaced by thinner seasonal sea ice.
  • The duration of seasonal lake ice cover is declining, with earlier spring break-up and later freeze-up in the fall.
  • Permafrost temperatures and the thickness of the active layer are increasing.

All of these changes are impacting northern communities in particular – and projections indicate continued warming into the future. Food security for many Indigenous and rural residents is threatened through problems accessing traditional hunting grounds (changing sea ice conditions), a shortened winter road season limiting the time available to bring in supplies overland and also changes to the range of some food species (both marine and on land). Thawing permafrost is causing damage to buildings and other infrastructure; increased variability of ice cover on lakes has made overland travel more hazardous and loss of coastal sea ice has resulted in increased wave action and coastal erosion, which threatens some coastal communities.12

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These fact sheets are based on text from Susan Hassol, and ClimateData.ca would like to acknowledge her contribution, as well as those from the Climate Research Division (Environment and Climate Change Canada), the Canadian Forest Service (Natural Resources Canada) and our regional climate service partners.

References

  1. Meredith M, Sommerkorn M, Cassotta S, Derksen C, Ekaykin A, Hollowed A, Kofinas G, Mackintosh A, Melbourne-Thomas J, Muelbert MMC, Ottersen G, Pritchard H, Schuur EAG (2019): Polar Regions. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [Eds. Pörtner H-O, Roberts DC, Masson-Delmotte V, Zhai P, Tignor M, Poloczanska E, Mintenbeck K, Alegría A, Nicolai M, Okem A, Petzold J, Rama B, Weyer NM].pp. 203-320. https://www.ipcc.ch/srocc/
  2. Miller GH, Lehman SJ, Refsnider KA, Southon JR, Zong (2013): Unprecedented recent summer warmth in Arctic Canada. Geophysical Research Letters 40: 5745-5751. https://doi.org/10.1002/2013GL057188
  3. https://www.noaa.gov/news/2019-was-2nd-hottest-year-on-record-for-earth-say-noaa-nasa
  4. Zhang X, Flato G, Kirchmeier-Young M, Vincent L, Wan H, Wang X, Rong R, Fyfe J, Li G, Kharin VV (2019): Changes in Temperature and Precipitation Across Canada. Chapter 4 in: Canada’s Changing Climate Report [Eds. Bush E, Lemmen DS]. Government of Canada, Ottawa, Ontario, pp 112-193. http://www.changingclimate.ca/CCCR2019
  5. Kug J-S, Jeong J-H, Jang Y-S, Kim B-M, Folland CK, Min S-K, Son S-W (2015): Two distinct influences of Arctic warming on cold winters over North America and East Asia. Nature Geoscience 8: 759-762. https://doi.org/10.1038/ngeo2517
  6. Collins M, Knutti R, Arblaster J, Dufresne J-L, Fichefet T, Friedling­stein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M, Te­baldi C, Weaver AJ, Wehner M (2013): Long-term climate change: projections, commitments and irreversibility. In: Climate Change 2013: The Physical Science Basis; Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (Eds)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA; p. 1029–1136. https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chap­ter12_FINAL.pdf
  7. Lee SH (2019): Wintertime North American Weather Regimes and the Arctic Stratospheric Polar Vortex. Geophysical research Letters 46: 14892-14900. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019gl085592.
  8. Pedersen RA, Cvijanovic I, Langen PL, Vinther BM (2016): The Impact of Regional Arctic Sea Ice Loss on Atmospheric Circulation and the NAO. Journal of Climate 29: 889-902. https://doi.org/10.1175/JCLI-D-15-0315.1
  9. Tang Q, Zhang X, Yang X, Francis JA (2013): Cold winter extremes in northern continents linked to Arctic sea ice loss. Environmental Research Letters 8. https://doi.org/10.1088/1748-9326/8/1/014036
  10. Wallace JM, Held IM, Thompson DWJ, Trenberth KE, Walsh JE (2014): Global Warming and Winter Weather. Science 343: 729-730. DOI: 10.1126/science.343.6172.729
  11. Derksen C, Burgess D, Duguay C, Howell S, Mudryk L, Smith S, Thackeray C, Kirchmeier-Young M (2018): Changes in snow, ice, and permafrost across Canada. Chapter 5 in Canada’s Changing Climate Report [Eds. Bush E, Lemmen DS]. Government of Canada, Ottawa, Ontario, pp 194-260. http://www.changingclimate.ca/CCCR2019.
  12. Larsen JN, Anisimov OA, Constable A, Hollowed AB, Maynard N, Prestrud P, Prowse TD Stone JMR (2014): Polar regions. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros VR, Field CB, Dokken DJ, Mastrandrea MD, Mach KJ, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC, Girma B, Kissel ES, Levy AN, MacCracken S, Mastrandrea PR, White LL (Eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1567-1612.