Holocene Glaciers of Western Canada
Menounos, B., Osborn, G., Clague, J.J. and Luckman, B.H. 2009. Latest Pleistocene and Holocene glacier fluctuations in western Canada. Quaternary Science Reviews 28: 2049-2074.
Menounos et al. report that "the Cordilleran ice sheet reached its maximum extent about 16 ka and then rapidly decayed," after which "a general expansion of glaciers began as early as 8.4 ka when glaciers overrode forests in the southern Coast Mountains." This expansion culminated with "the climatic [italics added] advances of the Little Ice Age," during which time glaciers "reached their maximum Holocene positions during the early 18th or mid-19th century." In fact, they state that the Cordilleran glaciers "were still close to their maximum positions in the early 1900s." In addition, and with respect to what was responsible for the record-breaking glacial expansion of the Little Ice Age, the four Canadian researchers state that "glaciers advanced during the Little Ice Age in response to cold conditions that coincided with times of sunspot minima."
When it is realized that the Little Ice Age was likely the coldest interval of the current interglacial period, and that it extended all the way up to the start of the 20th century in western Canada, it can be appreciated that the warming that has been experienced there subsequently is certainly nothing out of the ordinary. In fact, it actually represents a return to what was "ordinary" over great intervals of the prior millennia. Hence, it can be appreciated that to return to that more ordinary climatic state surely does not require the help of an increase in the atmosphere's CO2 concentration. The earth has experienced that condition many times before, without any increase in the air's CO2 content; and it can surely experience it again, without any increase in the air's CO2 content, as it indeed has done over the course of the 20th century, perhaps with a little help from its friend - the sun.