And the conclusions are not based on what type of thermometer is used : here's an article from last year about Japan's cherry blossom since the year 812 : Japan's cherry blossom 'earliest peak since 812'
The UK data isn't so reliable - the Japanese data is based on a single named cultivar throughout (i.e., no genetic variation component), whereas the UK data is based on much more general observations, so is affected by other factors, such as the intentional development and sale of earlier-flowering cultivars, where the date difference is due to genetics, not climate change. This particularly affects spring-flowering bulbs, where there is a strong market incentive for new cultivars that flower earlier than the natural species.
