Temperature change needed for complete loss of Greenland ice sheet: between 1 and 4 °C. (That's a change by, not a change to).
Effect of complete loss of Greenland ice sheet: 7.2 meter sea level rise.
Your attempt at nit picking, if it were valid, would actually makes it much worse: a temperature increase sufficient to turn "-22c" into "we don't need to worry about cold batteries" requires close to double the difference between today and the highest estimated average global temperature ever in the biological history of the planet, and that temperature happened before trees had evolved.
For example, naïvely adding 22 C (22.5 says Wiki) to the average so that the coldest was no longer below freezing, your Fort McMurray would have a new July average high of 46.2 C, which is above the current average of Death Valley 10 months of the year and pretty close the other two.