Editing Ellesmere Island (section)

===Climate===
Ellesmere Island has a [[tundra climate]] ([[Köppen climate classification|Köppen]] ''ET'') and an [[ice cap climate]] ([[Köppen climate classification|Köppen]] ''EF'') with the temperature being cold year-round.{{citation needed|date=May 2023}} Two semi-permanent air systems dominate the weather: the high-pressure northern [[polar vortex]] and a low-pressure area which forms in different sites between Baffin Bay and the Labrador Sea.{{r|"Dick"|p=25}} Prevailing winds on Ellesmere are northwesterly, cold, and of low humidity due to ice cover over the Arctic Ocean.{{r|"Dick"|p=32–33}} Seasonal shifts on Ellesmere are sudden and striking: winters are long and harsh, summers short and relatively abundant, with spring and autumn being brief intervals of transition.{{r|"Dick"|p=42}}

Fog regularly occurs near open water in September.{{r|"Dick"|p=22}} While the major air systems strengthen towards their annual peak in winter, the Arctic and Atlantic air masses collide in autumn to produce severe storms at Ellesmere.{{r|"Dick"|p=22, 25}} The storm season peaks in October and persists until the sea freezes.{{r|"Dick"|p=46}} The polar vortex strengthens during the polar night and gives rise to easterly winds which are major hazards for populations, especially given the very low temperatures. January winds have been recorded at {{cvt|104|kph}} with gusts to {{cvt|130|–|145|kph}} at Fort Conger and {{cvt|65|–|80|kph}} at Lake Hazen.{{r|"Dick"|p=25}} Very cold temperatures continue until April and no month passes without experiencing freezing temperatures.{{r|"Dick"|p=33}}

Snowfall begins in late August and does not melt until the June thaw. The seasonal shift in daylight is also extreme.{{r|"Dick"|p=42}} The polar night lasts from four-and-a-half months in the north to about three months in the south.{{r|"Dick"|p=44}}

====Regional variation====

Ellesmere's Arctic marine climate is strongly affected in the north by Arctic Ocean currents and the polar vortex, while the climate of the southeastern coast is influenced by the warm Atlantic water of the [[West Greenland Current]].{{r|"Dick"|p=23}} Interior regions shielded by the island's high mountain ranges experience distinctive [[continental climate|quasi-continental microclimates]].{{r|"Dick"|p=9}}

The highest precipitation is on the northern coast, averaging {{cvt|80|to|100|mm}}. On the south side of the Grant Land mountains, only {{cvt|20|mm}} reaches the Hazen Plateau.{{r|"Dick"|p=32–33}}

The average number of snow-free days varies from 45 days on the north coast to 77 days in the Eureka–Tanquary corridor.{{r|"Dick"|p=33}}

Winters are considerably colder in the interior. At Lake Hazen, Peary's expedition recorded daytime temperatures of {{cvt|-64|F|order=flip}} in February&nbsp;1900, and a Defence Research Board party recorded temperatures as low as {{cvt|-69.2|F|order=flip}} in the winter of 1957–58.{{efn|While Dick 2001 gives this temperature as {{cvt|-70|C}},{{r|"Dick"|p=43}} this is the only temperature the source provides in Celsius on that and the adjacent pages and appears to be a typo. Other sources for this International Geophysical Year observation station give the temperature as {{convert|-69.2|F}}, noting that this stands as the coldest temperature reported in the Arctic Archipelago.<ref>{{cite web|url=https://www.canadashistory.ca/explore/environment/canada-s-coldest-day|title=Canada's Coldest Day|website=Canada's History|first=David W.|last=Phillips|date=3 April 2016|publisher=Canada's History Society}}</ref> }} Nonetheless, there are archaeological remains of winter dwellings of both Independence and [[Thule people|Thule cultures]] in the interior.{{r|"Dick"|p=43–44}}
{{Grise Fiord weatherbox}}
{{Eureka, Nunavut weatherbox}}
{{Alert, Nunavut weatherbox}}

====Climate change====
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Ice core samples from Ellesmere's ice caps show a general warming interval between 400 BCE and 1300 CE.{{r|"Dick"|p=27}}
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A [[Paleolimnology|paleolimnological]] study of algae in the sediments of shallow ponds on Cape Herschel (which faces Smith Sound on Ellesmere's eastern coast<ref name="Smol1994"/><ref>{{cite cgndb |id=OAHEA|name=Cape Herschel}}</ref>) found that the ponds had been permanent and relatively stable for several millennia until experiencing ecological changes associated with warming, beginning around 1850 and accelerating in the early 2000s. During the 23-year study period, an ecological threshold was crossed as several of the study ponds had completely desiccated while others had very reduced water levels. In addition, the wetlands surrounding the ponds were severely affected and dried vegetation could be easily burned.<ref name="Douglas2007"/>