Phenology records the dates of recurring natural events: first almond blossom, swallow arrival, leaf fall, grape ripening. These events are sensitive to temperature and photoperiod, making them biological climate indicators.
Climate change
In Spain, almond blossom has advanced 2–3 weeks since the 1970s. Grape harvest is advancing ~10 days per decade in many European wine regions. Historical phenological records are among the most direct and understandable evidence of global warming.