The false spring of 2012, earliest in North American record
Phenology - the study of recurring plant and animal life cycle stages, especially their timing and relationships with weather and climate - is becoming an essential tool for documenting, communicating, and anticipating the consequences of climate variability and change. For example, March 2012 broke numerous records for warm temperatures and early flowering in the United States [Karl et al., 2012; Elwood et al., 2013]. Many regions experienced a “false spring,” a period of weather in late winter or early spring sufficiently mild and long to bring vegetation out of dormancy prematurely, rendering it vulnerable to late frost and drought. As global climate warms, increasingly warmer springs may combine with the random climatological occurrence of advective freezes, which result from cold air moving from one region to another, to dramatically increase the future risk of false springs, with profound ecological and economic consequences [e.g., Gu et al., 2008; Marino et al., 2011; Augspurger, 2013]. For example, in the false spring of 2012, an event embedded in long-term trends toward earlier spring [e.g., Schwartz et al., 2006], the frost damage to fruit trees totaled half a billion dollars in Michigan alone, prompting the federal government to declare the state a disaster area [Knudson, 2012].