It can be done. But this wasn't done for efficiency or to fight climate change, but out of solidarity with Ukraine, and Europe had to reduce its dependency on Russian gas.
Still, if we can do it for that, can't we do it for climate change too? It's a more abstract problem though; not as concrete, immediate and urgent as a war. And frankly, I wouldn't mind being able to put my temperature back to 20 next winter. 19 doesn't sound like a big change, but it's still a bit chilly.