Perennial plant

Spring (device)

Climatology

Engineering

Ecology

Representative Concentration Pathways

Biology

Dormancy

Frost (temperature)

Climate model

Geology

Mechanical engineering

Chilling requirement

Global warming

Climate change

Geography

Political science

Agronomy

Environmental science

Misrepresentation

Meteorology

Atmospheric sciences

Phenology

Germination

Ecosystem

Nature Communications

Spring warming substantially advances leaf unfolding and flowering time for perennials. Winter warming, however, decreases chilling accumulation (CA), which increases the heat requirement (HR) and acts to delay spring phenology. Whether or not this negative CA-HR relationship is correctly interpreted in ecosystem models remains unknown. Using leaf unfolding and flowering data for 30 perennials in Europe, here we show that more than half (7 of 12) of current chilling models are invalid since they show a positive CA-HR relationship. The possible reason is that they overlook the effect of freezing temperature on dormancy release. Overestimation of the advance in spring phenology by the end of this century by these invalid chilling models could be as large as 7.6 and 20.0 days under RCPs 4.5 and 8.5, respectively. Our results highlight the need for a better representation of chilling for the correct understanding of spring phenological responses to future climate change.

Overestimation of the effect of climatic warming on spring phenology due to misrepresentation of chilling