Background
The authors write that "climate warming fosters an earlier spring green-up that may bring potential benefits to agricultural systems." However, they say that advances in green-up timing may leave early-stage vegetation growth vulnerable to cold damage when hard freezes follow green-up, resulting in what has come to be known as a false spring.

What was done
To explore what may have happened in this regard throughout the contiguous United States as the atmosphere's CO2 concentration trended upward from 1920 to 2013, Peterson and Abatzoglou examined the spatiotemporal patterns of green-up dates, last spring freezes and false springs based on daily maximum and minimum temperature observations for 1218 U.S. Historical Climatology Network stations that they obtained from the Global Historical Climatology Network database of Menne et al. (2012).

What was learned
The two researchers report finding "widespread earlier green-up and last spring freeze dates over the study period," with "the last spring freeze date advancing to earlier in the year relative to green-up date," which "resulted in a reduction in false springs, notably over the past 20 years, except across the intermountain western United States." And they further found that a sensitivity experiment demonstrated that "observed decreases in false springs are consistent with a warming climate."

What it means
As a result of their several findings, Peterson and Abatzoglou conclude that (1) "plant communities and agriculture will likely take advantage of earlier warm temperatures," that (2) "decreased false spring exposure may enhance ecosystem carbon sequestration across the continental US," additionally citing Hufkens et al. (2012) in this regard, that (3) their sensitivity analysis suggests "continued decreases in false springs with further warming," although they add that (4) "it is unlikely that false springs will disappear entirely."

References
Hufkens, K., Friedl, M.A., Keenan, T.F., Sonnentag, O., Bailey, A., O'Keefe, J. and Richardson, A.D. 2012. Ecological impacts of a widespread frost event following early spring leaf-out. Global Change Biology 18: 2365-2377.

Menne, M.J., Durre, I., Vose, R.S., Gleason, B.E. and Houston, T.G. 2012. An overview of the Global Historical Climatology Network-Daily database. Journal of Atmospheric and Oceanic Technology 29: 897-910.