That Gulf Stream theory is bogus IMHO. We do not have a Gulf Stream on the west coast US. We have a cold Alaska Stream. Portland and Seattle are never buried in snow because of a lack of a Gulf Stream. Neither is the UK. Could a less active sun or cooling planet be the causation for the Jet Stream blocking patterns ?
The best explanation for Russian heat waves (which BTW continued into November) and the western European cold snap is blocking, negative Arctic Oscillation which includes a weak polar jet, high pressure over the north pole (instead of low pressure). All of those factors interact. A possible underlying cause could be solar since solar UV is very low and that causes blocking. Also low solar magnetic lets more galactic cosmic rays through and those can change the patterns of clouds and also cause blocking in extreme cases.
A weak sun means a little less energy, but not only enough for a .1 degree change or so. But the weak sun magnetically means changes in weather patterns which ultimately can result in global cooling. But even if there is cooling from weather, a lot of energy is left in the ocean to keep us warm or warming, so I wouldn't be worried about an ice age just yet.