Climate change delays spring phenology in New York City parks

Phenology, the study of how seasonal and environmental cues trigger life-cycle changes in living organisms, is increasingly being used to track the impacts of climate change. By observing how biological processes link to non-biological changes, such as temperature and daylight, scientists can monitor shifts in plant budding, animal migration, and fish spawning.

A study by researchers at the Yale School of the Environment focused on urban ecosystems in New York City, analyzing two decades of satellite imagery. The findings indicate that global warming is delaying the start of the growing season in city parks. This delay is particularly evident in medium-sized parks, which lack the cooling capacity of larger parks to counteract warming effects due to high edge-to-area ratios.

As winters become milder, trees in these urban areas experience shortened chilling periods. This lack of sufficient cold hours means trees require more heat accumulation to break dormancy, often resulting in trees remaining dormant longer despite rising temperatures. These shifts in phenology can lead to reduced carbon uptake and altered pollen seasons, presenting challenges for urban biodiversity and ecological management.