I think that's what they mean. AFAIK the entire UK is north of the Canadian border. The people, economy, infrastructure and natural environment are nowhere near ready to deal with a Canadian-style winter.

Most of Canada - where it's REALLY cold - is mainly cold because it's so far away from water.

Nova Scotia is much colder than the UK - but it's not like it's Siberia.

I imagine the UK is highly unlikely to get colder than Nova Scotia.

Nova Scotia winter weather would be quite a shock for the UK. I don't think it would be catastrophic but very unpleasant for sure.

You can look at a map. Scotland is at the same latitude as Hudson Bay. The Belcher Islands are not known for mild winters despite being in the middle of that bay: https://www.worldweatheronline.com/belcher-islands-weather-a...

https://commons.wikimedia.org/wiki/File:K%C3%B6ppen-Geiger_C...

In short: yes it will turn into Siberia.

The Gulf Stream is an ocean current than brings warmth from the Gulf of New Mexico up the US's coastline and across the Atlantic to western Europe. It's estimated to have a several-degree-C warming effect.

The Gulf Stream doesn't seem to be slowing down, so a direct temperature-related change isn't really a concern, but what still is is the ice melt from Greenland - that's mostly freshwater and it getting dumped into the Atlantic could still disrupt it.

Almost all climate variability in either direction is unpleasant for settlements long built for a certain expected range.