In a new study published in Flora, we show how social media can be used for "incidental citizen science." From photos posted to a social site, we mapped countrywide patterns in nature over a decade in relatively fine detail.

Our case study was the annual spread of cherry blossom flowering across Japan, where millions of people view the blooming each year in a cultural event called "hanami." The flowering spreads across Japan in a wave ("sakura zensen" or 桜前線) following the warmth of the arriving spring season.

The hanami festival has been documented for centuries, and research shows climate change is making early blossoming more likely. The advent of mobile phones—and social network sites that allow people to upload photos tagged with time and location data—presents a new opportunity to study how Japan's flowering events are affected by seasonal climate.

Why are flowers useful to understand how nature is being altered by climate change?