Plants are budding and flowering earlier than usual. What does this mean for pollinators that are used to a certain rhythm and timing for the foods they need access to so they can survive? Is a climate crisis behind this changing pattern?

This post could just as easily have been called, The Enormous Value of Citizen Science.

In the UK, plants are flowering a whole month earlier than usual according to scientists at the University of Cambridge who recently analyzed the first flowering dates of some 406 species of flowers and found a connection to warmer temperatures in spring.

Scientists used a citizen science database with records that go all the way back to the mid-18 century, and range geographically from the Channel Islands to Shetland, and from Northern Ireland to Suffolk. Researchers based their analysis on over 400,000 observations of the 406 plant species of flowers from Nature’s Calendar, which is maintained by the Woodland Trust, and collated the first flowering dates of trees, shrubs, herbs, and climbers with instrumental temperature measurements.

Between 1987 and 2019, they found, the average first flowering date is a full month earlier than the average first flowering date between 1753 and 1986. The same period coincides with accelerating global warming caused by human activities. The results were reported in Proceedings of the Royal Society B.

This 1:10-minute video by The Woodland Trust asks for more citizen scientists to get involved in tracking the seasons:


This can indicate serious consequences for the UK’s ecosystems and agriculture. Species that depend on these flowers and plants will be ‘mismatched.’ Ecological mismatch means they are no longer in sync with the plants that sustain them. They normally synchronize their migration or hibernation cycles, so they have food when they emerge. This change will put them out of sync and may imperil their survival over time if they cannot adapt quickly enough.

This change has far-reaching repercussions. For instance, farmers and gardeners will also be affected. If fruit trees flower early after a mild winter, crops can be killed off if the blossoms are then hit by a late frost.

Professor Ulf Büntgen from Cambridge's Department of Geography, is the study's lead author. He indicates that to really understand what climate change is doing to our world we need much larger datasets that look at whole ecosystems over a long period of time.

There is such a dataset in the UK. Since the 18th century, observations of seasonal change have been recorded by scientists, naturalists, amateur and professional gardeners, and organizations like the Royal Meteorological Society. In 2000, the Woodland Trust joined forces with the Centre of Ecology & Hydrology and collated these records into Nature’s Calendar. It currently has about 3.5 million records that go as far back as 1736.

Büntgen describes Nature’s Calendar as an incredibly rich and varied data source. Anyone in the UK can submit a record to Nature’s Calendar by logging their observations of plants and wildlife. It can be used to quantify how climate change is affecting the function of various ecosystem components in the UK.

The researchers classified observations by location, elevation, and whether the areas were urban or rural. The first flowering dates were then compared with monthly climate records. The average first flowering advanced by a full month and is strongly correlated with rising global temperatures.

According to Büntgen, the results are truly alarming because of the ecological risks associated with earlier flowering times. Early flowering plants can be hit and killed by late frost. The bigger risk is ecological mismatch.  Much wildlife, such as plants, insects and birds have co-evolved to a point that they are synchronized in their development stages. First the plant flowers and attracts a particular insect, which in turn attracts a particular bird, and so on. When one component in this delicate balance responds faster than the others, a risk exists that they will be out of sync. This can lead to the collapse of species that can’t adapt quickly.

Büntgen says that if global temperatures continue to increase at the current rate, spring in the UK may start in February eventually. Species in forests, gardens and on farms could have serious problems.

Co-author Professor Tim Sparks from Cambridge's Department of Zoology suggests that continued monitoring is necessary to ensure that we better understand the consequences of a changing climate. Contributing records to Nature’s Calendar is an activity we can all engage in.