In Japan, a sharp increase in a sales tax earlier this year has hurt consumer spending. And Prime Minister Shinzo Abe has largely failed to boost business investment and draw more women into the labor force, two changes he had promised as part of a plan to revive his country’s weakened economy. The Bank of Japan recently expanded its bond-buying program, but bigger government policy changes will be needed to revive Japan’s economy in 2015.

In Europe, government officials and central bankers in the 18-country eurozone have been slow and timid in boosting their economies, even though inflation is less than 0.5 percent and the unemployment rate is more than 11 percent. The European Central Bank should be buying government bonds to pump more money into the economy, a policy known as quantitative easing. But it has been reluctant to do so because German officials are opposed to the policy, which they think would serve to transfer wealth from strong euro nations to weaker ones. It should come as no surprise that the eurozone grew at just 0.2 percent in the third quarter of this year, according to data released on Friday.

The big losers in all this are nations that depend on commodity exports, like Russia, Brazil and Iran. Some of these countries, particularly Russia and Iran, already have substantial economic problems because of Western sanctions and government mismanagement. Brazil’s economy was slowing before the decline in commodity prices, and it faces a difficult 2015. President Dilma Rousseff, who recently was re-elected by a narrow margin, needs to diversify Brazil’s economy by investing in infrastructure and making it easier for entrepreneurs to start businesses.

The drop in prices, however, has been good for the United States, which is growing faster than other industrialized economies. Lower oil prices in particular will provide a much needed stimulus to consumers, particularly lower-income Americans who spend a larger percentage of their incomes on fuel; analysts say cheaper fuel has helped raise retail sales in the United States.

But America’s economy could struggle in the coming year if Europe and Japan slip into another recession. About 25 percent of all American exports went to those two markets in the first nine months of the year.