Here’s an early Christmas present for the economists of Wall Street.

2015 may be the first year in five in which they get to raise forecasts for global economic growth rather than cut them.

That may be fanciful thinking as the year ends with Russia in crisis, investors rediscovering volatility and central banks returning to the monetary pumps. Other potential risks include more geopolitical flare-ups, elections from Greece to the U.K., a hard landing in China, a premature exit from Federal Reserve stimulus and a slide toward deflation in Europe and Japan.

Recent history is on the side of the pessimists. A year ago, the median forecast of economists surveyed by Bloomberg News was for growth of 3.5 percent in 2014. It has since been scaled back to 3.2 percent. Cuts were also made in 2011, 2012 and 2013.

Trying to explain this year’s miss, economists at JPMorgan Chase & Co. blamed bigger-than-anticipated slowdowns in emerging markets and a failure by the euro area to gain traction.

Still, in the holiday spirit, here are some grounds for optimism that the forecast of the Bloomberg News survey of 3.5 percent expansion in 2015 will, for once, prove too low.