When you say mid-latitude winters have exhibited a cooling trend what does that mean exactly? An increase in cold-air outbreak events? Or average winter temperatures is actually decreasing? I am confused about this because I look at Midwest observational winter climate data and see that our average winter minimum temperatures are increasing the fastest out of any other annual temperature variable --- winters are warming faster than summer are heating up! So if it is not reduced Arctic sea ice that is causing colder mid-latitude winters, what are the possible changes in the atmospheric circulation that is actually driving both these changes? Thoughts if inter-annual modes of climate variability like Arctic Oscillation are responsible?