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Earlier flowering trees as a result of climate change – How does global warming affect nature?

A research team recently presented the world’s five longest time series of leaf shedding related to earlier flowering trees. The trees in question are a cherry tree in Basel-Landschaft and a horse chestnut in Geneva. The progress of flowering observed in all series is a clear sign of climate warming. This has accelerated significantly since the 1980s. To learn more about this process, here is some information about the effects of climate change on nature.

How climate change is causing earlier flowering trees

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Researchers are becoming increasingly interested in the role that climate change and warming temperatures may have on flowering trees. As the weather gets warmer in the spring, many biological phenomena also take place earlier, such as birds breeding and trees beginning to bloom and drop leaves. Humans have been observing these natural events for centuries, and the five longest time series in the world are presented here. They are all strikingly consistent with the acceleration of global warming since the 1950s, which intensified in the 1980s. In addition, cherry blossoms begin on average 11 days earlier than they did before 1950, and in Japan, the 2021 blossom season also began earlier than at any other time in the past 1,200 years. For climate scientists, this is concrete evidence that global warming is having a major impact on ecosystems, and this effect can be seen worldwide.

in spring pink blossoms fell from tree in park

As a result of climate change, trees and shrubs around the world are germinating early and also flowering earlier. That’s according to an assessment published in the journal Nature. Of the five longest known time series of these plants. Since the mid-1980s, all data series show an earlier onset in parallel with the observed warming in the northern hemisphere. Under the technical term phenology, researchers study annually recurring biological processes such as the beginning of plant flowering or the start of bird migration. They divide the year into ten seasons rather than four. Spring, for example, is divided into early spring, first spring, and full spring. Data on the onset of characteristic events, some of which have been available for decades or even centuries, now allow conclusions to be drawn about the effects of climate change on nature.

Effects of climate warming

spring flower attracts ladybugs

The events described above could disrupt wildlife relationships and lead to species collapse if they do not adapt quickly enough. The findings are truly alarming because of the ecological risks associated with earlier blooms. A late frost can kill early blooms, but an even greater risk, they said, is the ecological mismatch that occurs when a wildlife relationship is disrupted by temporal changes from the life cycle, such as breeding or migration. A particular plant flowers and then attracts insect species , which attract certain bird species, and so on.

magnificent cherry blossoms in spring at climate change 2021


By far the longest time series is that of the cherry blossom in Kyoto, Japan. This is an important cultural event whose beginning is recorded since 812 AD. The oldest time series in Europe records the leaf drop of several deciduous trees in southeastern Britain, such as oaks and other tree species, since 1950. No fewer than two of the five time series are in Switzerland. The Grand Conseil de la République et canton de Genève has monitored a horse chestnut since 1808, and the Ebenrain Agricultural Center and MeteoSwiss have monitored a cherry tree in the canton of Basel-Landschaft since 1894.

Significantly earlier flowering trees and leaf drop observed

two young women meet during pandemic and autumn in park

The researchers used observations for four plant categories based on elevation: trees, shrubs, herbs and climbers. Herbs experienced the most significant shift in their first date of flowering at 32 days. This change could be due to short-lived plants with faster turnover rates being able to adaptively develop more quickly. However, whether they can do so quickly enough to keep pace with climate change is unknown. On average, in these time series, leaf drop or flowering began six to 30 days earlier than before 1950. The 2021 cherry blossom in Japan is particularly impressive. This began earlier than at any time in the last 1200 years. These five time series are not even in those regions of the world where the climate has warmed the most. In Central Asia, for example, an even more extreme temporal shift of life cycle events is to be expected.

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The time series of flowering and leaf drop are clear indicators to science. However, this is also an easily observable phenomenon for the general population. Moreover, these are concrete signs of accelerating climate change. Therefore, phenology, which refers to the science that studies biological processes in relation to seasonal climate variability, could be a very good tool. This will allow researchers to better communicate the effects of climate change on living organisms. According to the authors of this study, this can help raise awareness among policy makers and future generations about current climate change and its negative effects.