Editing IPCC:AR6/WGII/Chapter-14 (section)

==== 14.5.6.2 Cold-Related Mortality ====

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Winter season mortality rates are generally high in high-income regions such as North America, with most of that mortality due to cardiovascular diseases ( [[#Ebi--2013|Ebi and Mills, 2013]] ). It is important to differentiate between mortality related to cold temperatures and mortality due to other factors that vary with season ( [[#Ebi--2013|Ebi and Mills, 2013]] ; [[#Ebi--2015|Ebi, 2015]] ). Warmer temperatures do not always equate to lower winter mortality: many cold-related deaths do not occur during the coldest times of year or in the coldest places ( ''high confidence'' ) but occur during the beginning or end of the winter season ( [[#Barnett--2012|Barnett et al., 2012]] ; [[#Lee--2014|Lee et al., 2014]] ; [[#Schwartz--2015|Schwartz et al., 2015]] ; [[#Sarofim--2016b|Sarofim et al., 2016b]] ; [[#Smith--2019|Smith and Sheridan, 2019]] ). Warmer US cities generally experience more mortality from extreme cold events and cold temperatures than colder cities in the USA and Canada ( [[#Lee--2014|Lee et al., 2014]] ; [[#Gasparrini--2015|Gasparrini et al., 2015]] ; [[#Schwartz--2015|Schwartz et al., 2015]] ; [[#Wang--2016|Wang et al., 2016]] ; [[#Smith--2019|Smith and Sheridan, 2019]] ). While mortality rates linked to direct cold exposure (e.g., hypothermia, falls and fractures) is generally low, the relatively higher mortality during milder temperatures is thought to be largely due to respiratory infections and cardiovascular impacts ( [[#Lee--2014|Lee et al., 2014]] ; [[#Gasparrini--2015|Gasparrini et al., 2015]] ), which, although correlated with temperature, may not be caused by cold temperatures ( [[#Ebi--2013|Ebi and Mills, 2013]] ; [[#Ebi--2015|Ebi, 2015]] ; [[#Sarofim--2016a|Sarofim et al., 2016a]] ). When separating the effects of cold temperatures from the effects of the winter season, one study found that cold temperature did not drive mortality and suggested that winter season excess mortality was due to seasonal factors other than temperature (e.g., influenza, seasonal gatherings) ( [[#Kinney--2015|Kinney et al., 2015]] ).

Mortality attributed to cold temperatures has increased in the USA and remained stable in Canada from 1985 to 2012 despite increasing winter temperatures ( [[#Vicedo-Cabrera--2018b|Vicedo-Cabrera et al., 2018b]] ). Some attenuation in cold-related mortality in Mexico and warmer US states is projected under climate change, but less so in colder climates in northeast USA and Canada, with statistically insignificant trends in some regions and increasing cold-related mortality in other regions ( [[#Li--2013|Li et al., 2013]] ; [[#Mills--2015b|Mills et al., 2015b]] ; [[#Schwartz--2015|Schwartz et al., 2015]] ; [[#Sarofim--2016a|Sarofim et al., 2016a]] ; [[#Wang--2016|Wang et al., 2016]] ; [[#Gasparrini--2017|Gasparrini et al., 2017]] ; [[#Vicedo-Cabrera--2018a|Vicedo-Cabrera et al., 2018a]] ; [[#Lee--2019|Lee et al., 2019]] ). These reductions in cold-related mortality are generally considered relatively small.

Observed and projected trends in winter mortality highlight that non-climate factors may have a greater role in driving winter mortality than cold temperature, and that these deaths are expected to occur with or without climate change ( [[#Ebi--2013|Ebi and Mills, 2013]] ; [[#Ebi--2015|Ebi, 2015]] ; [[#Sarofim--2016a|Sarofim et al., 2016a]] ). This challenges the assumption that warmer winters due to climate change would dramatically lower winter season mortality ( ''medium evidence, medium agreement'' ).

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