A total Russian gas shutoff would plunge Europe into a 'multi-winter crisis,' says RBC's global commodity chief

• A total shutoff from Russian gas could lead to a "multi-winter crisis" for Europe, RBC's Helima Croft said.
• EU countries have made progress in building up their gas reserves, but only with the help of Russian flows so far.
• Any alternative supplies are sparse, meaning Europe is facing a severe supply problem in the upcoming years.

A total Russian gas shutoff would send Europe into an energy crisis that would last multiple winters and would be "very expensive" for governments to keep energy prices affordable, according to RBC's global commodity chief Helima Croft.

"I think we're in this situation with Russia right now where we just don't know how far they're going to go in terms of weaponizing energy," Croft said in an interview with CNBC on Tuesday, referring to the recent shutoff of Nord Stream 1, Europe's main gas pipeline. 

Russian officials have said gas flows will not resume until European Union sanctions are lifted, spiking concerns that Europe could be choked off completely from Russian gas supplies this winter.

In preparation, the EU has proposed a voluntary 15% gas-usage cut, and reached 80% natural gas storage nearly two months ahead of schedule. Countries like Germany have also made plans to expand their natural gas infrastructure to boost production in future years.

But EU countries were able to build up their gas storage only because Russian gas flows were uninterrupted up until this summer, when the Nord Stream 1 pipeline was first slashed to 20% capacity, Croft said. Countries like Germany have also never subsisted off of gas reserves throughout the winter without additional flows.

"This may not be a crisis just for this winter. This could be a multi-winter crisis, because if there is no gas going forward, Europe is going to have a huge supply problem going forward, even with this infrastructure build-up," she added.

And alternative gas supplies for Europe look sparse: Norway has stepped up gas production by 10% to fill the hole in Russian supplies, but energy executives Croft spoke to in Norway have said the country is nearly "tapped out," and is uncertain how much support they can provide this winter.

But the energy market may have one bright spot in OPEC+. Although the cartel recently announced they would trim production by 100,000 barrels per day, Croft said that would allow OPEC to step in if there is a sudden cut to supplies in the market. 

Though, those measures will only go so far, she added.

"But if we get a very cold winter in Europe, I don't see how we're not going to get through this without major industrial curtailment rationing, is going to be very, very expensive in terms of what governments are going to have to pay to keep their populations at all satisfied with energy prices," Croft said.