My winter low temperatures are usually about 2 weeks of -20 to -30 at night ( real temps not wind chill). The coldest we got last year was 0 degrees.

We got a season total of 13 inches of snow last year. The "season" for us is November through April usually. 9 of those 13 inches fell before december 1st and melted 2 days after due to 60 degree temps. In a place very close to Canada, we didn't have enough snow in the woods to cross country ski without riding on branches and rocks. We got the least amount of snow we've had in my lifetime, and I'm 40.

My dad is a logger, and use to do much of his logging in the winter. Why? Because the ground freezes and its easier to get heavy equipment in and out to move trees without having to deal with the mud, tear up the land, and create erosion from the tracks. His window of opportunity has had an entire month shaved off the beginning and the end.

I am still harvesting non-frosthardy vegetables from my garden and I am in zone 4a. I usually get first frost kill in mid-September.

Normally we have a dusting of snow before Halloween, and it gets so chilly we have to wear a snowsuit under the costume. For the last 4out of 5 years, we haven't had to do that. Only a light jacket underneath. We still have 2 weeks left, so I shouldn't count my chickens before they hatch, so to speak.

Invasive insect species are now moving into and settling in areas that they used to never overwinter in before. Yay for brown recluse spiders and poisonous snakes? Never had to deal with these before.

The lakes in my area have what is called "ice in" and "ice out" dates. That's when the surface of the lake freezes and stays frozen until the ice out date, when the ice obviously recedes. Like the logging season, this is getting weeks shaved off in the beginning and end.

All of this is personal observation, not anything I've read in an article. It could be a natural cycle we're seeing, but I very seriously doubt that the amount of pollution we as a species put out on a daily basis has little to no effect on the atmosphere, the water supply, and the soils.