That's bullocks. That's not how "global warming" works, which is why scientists are typically careful to call it "climate change." The temperature of a region is predominantly affected by ocean and air currents. Sunny Marseille in France with its Mediterranean climate is the same latitude as New England. Montreal gets bitter cold for 5 months of the year but London, a full 5deg further north, gets a few days of snow and a lot of rain.

These differences in regional weather at the same or similar latitudes are waaaaay bigger than the few degrees global average increase we see in world-is-ending predictions, and are entirely due to these ocean currents. If they slow down significantly or stop or change direction, it'd be a big freaking deal. If the English Midlands started getting winters like Winnipeg, Canada, that'd be a pretty big deal. While not a glacial period per se, it'd be worse than Europe's Little Ice Age, so I'm going to go ahead and call it what it is.