BRUSSELS — Restrictions on the sale of incandescent bulbs begin going into effect across most of Europe on Tuesday in the continent’s latest effort to get people to save energy and combat global warming. But even advocates concede the change is proving problematic.

Under the European Union rules, shops will no longer be allowed to buy or import most incandescent frosted glass bulbs starting Tuesday. Retailers can continue selling off their stock until they run out.

While some Europeans are eagerly jumping on the bandwagon, others are panicking and have been stockpiling the old-style bulbs for aesthetic or practical reasons. Others are resigned to the switch, if grudgingly.

“Why are we switching? Because we have to,” said Ralph Wennig, a 40-year-old photographer shopping on Monday at BHV, a Paris department store.