Plant Phenology & Climate Change

Data: The Weather Channel
Image: ProjectBudBurst

The timing of when a place warms up in the spring and when it cools down in the fall depends on Earth's climate. Regional differences in climate cause warm weather to arrive later in the spring at higher latitudes than at lower latitudes. But today global change in climate is having an impact on the timing of warming temperatures in the spring and cooling temperatures in the fall at locations worldwide.

As Earth's temperature rises, it becomes warmer earlier in the spring and stays warmer later into the fall at any given location. The opposite is true as well: if Earth's temperature were to cool, warm weather would show up later in the spring and cool weather would arrive earlier in the fall. Today, the global climate is warming. According to the Intergovernmental Panel on Climate Change, the multinational organization that summarizes the current state of knowledge about climate, Earth's average temperature has warmed 0.6°C (1.0°F) during the 20th Century. This modest number averages all the seasonal variations – the cold winters and hot summers – as well as all the differences in latitude – the cold poles and warm tropics – which can make it difficult to imagine the impacts in any given location.

We know that the amount of warming is not the same around the world. The Arctic, for example, is warming more quickly than other areas of the planet. Understanding the impacts that this worldwide phenomenon has on specific places is an area of active research. Project BudBurst is one of many studies investigating the impacts of global change in specific places. As the climate warms in the 21st Century, places around the world will continue to be affected by changing conditions. The temperature is predicted to rise another 1.8 to 4.0°C (3.2 to 7.2°F) during this Century.

Snow geese at Quivira National Wildlife Refuge, Kansas
Photo: USFWS

Changes in the timing of phases of the plant life cycle, known as phenophases, are directly affected by temperature, rainfall and day length. While these factors change through the year in places where there are distinct seasons, the first two – temperature and rainfall – are also changing in many regions because of climate change. For example, if climate change causes warmer temperatures, warm weather may occur earlier in the spring and it may stay warm later into the fall than in years past. It will still get cold in the winter and warm in the summer, but the plant growing season will be longer and that can have big impacts on living things.

That's where plants come in. By monitoring plants and noting when the first buds appear, when the first flowers appear, when leaves drop in the fall, and other parts of plant life cycles, scientists can figure out how seasonal patterns are changing, and make predictions for the future.

When you report to Project BudBurst about how and when the plants in your garden, park, town, or city are changing with the seasons, you are contributing scientific data that can help us understand how plants are responding to this year's seasons and long-term changes in climate. Scientists are using data about the timing of seasonal changes in species in computer models to predict how climate and ecosystems will change decades and even centuries into the future.