Changes in the colors of the Earth are revealing the far-reaching effects of climate change. Studies show that warming is delaying the fall of leaves and dulling the colors of autumn leaves, while also changing the colors of the oceans and Antarctica. In the United States, the peak of fall leaves has been delayed by nearly two weeks and may continue to be delayed in the future.
According to the BBC, the oak forests in Southamptonshire, England, are green longer this year than in previous years, and the red and yellow beauty seems to have been delayed by about two weeks. Studies have shown that climate change not only affects the time when leaves change color and fall, but also changes the color of leaves. At the same time, climate change has changed the color of the earth on a larger scale: the oceans and Antarctica are turning green rapidly.
Autumn colors are changing
A study published in Landscape Ecology in 2023 showed that combining remote sensing data with literature records, the peak of autumn leaves in Acadia National Park in the United States has been delayed by about 9 days between 1950 and 2021. The study speculates that by 2060, the best viewing period will be delayed to late October to early November. Since 1950, the average minimum and maximum temperatures in the area have risen by more than 1°C; the number of warm nights has increased by an average of 26 days per year, and the number of warm days has increased by an average of 17 days; the number of days with "downpours" has also increased by an average of 4 days per year.
Research published in Nature Climate Change in 2022 also showed that if climate change brings drought instead of increased rainfall, it may lead to early leaf aging.
Peak autumn leaf season from 1950 to 2021 (Image source: original paper)
In addition, research published in Science in 2023 showed that the time of leaf aging is not only affected by factors such as temperature, but also by the length of sunshine and photosynthesis in the early growth of leaves. Warm spring will cause leaves to sprout and age early; while warm autumn will delay leaf aging and leaf fall. For every 1°C increase in temperature, the time of leaf aging is 1.9 days earlier or 2.6 days later on average.
Higher temperatures before the summer solstice will cause leaves to begin aging earlier; higher temperatures after the summer solstice will delay the aging process of leaves, thereby delaying the time of leaf fall. (Image source: original paper)
Climate change also affects the color of leaves. Leaves contain a variety of pigments, in addition to chlorophyll, common ones are carotenoids and anthocyanins. Before leaves begin to age, chlorophyll is constantly synthesized and decomposed in leaves, maintaining a high level. Therefore, even though carotenoids are present in the leaves at this time, the leaves look green. But in autumn, the anthocyanin content in the leaves increases sharply, the chlorophyll content decreases, and the carotenoid content is basically stable, so the leaves show a variety of colors.
Faded oak leaves
Many factors affect the synthesis of anthocyanins. Anthocyanins are molecules that plants synthesize in large quantities when exposed to strong light and high sugar levels in the body, which is also related to the fact that mature fruits tend to appear brighter colors. The amount of anthocyanins in autumn leaves directly determines their red and yellow hues. Under warm and sunny days and cool nights, the accumulation of sugar promotes the synthesis of anthocyanins, making autumn leaves brighter. Today, the temperature rises at night, causing the autumn leaves to be dull.
The ocean is turning green
It is not just the autumn colors, but the changes in the color of the ocean are more significant. A study published in Nature in 2023 pointed out that over the past 20 years, data collected by satellites' Moderate Resolution Imaging Spectrometers showed that 40% of the world's surface oceans are rapidly turning green, especially in tropical waters. Scientists believe that climate change has caused the ocean surface to warm and stratify, making it difficult for nutrients from the deep to rise, which may make it easier for some phytoplankton and algae to survive, changing the color of the ocean.
Measurements of ocean color by satellite's Moderate Resolution Imaging Spectrometer (Image source: NASA and Joshua Stevens, using Landsat data from the U.S. Geological Survey and MODIS data from LANCE/EOSDIS Rapid Response)
Green expansion in Antarctica
The color change in Antarctica is also very obvious. Research published in Nature Geoscience in 2023 showed that the vegetation coverage of the Antarctic Peninsula has increased nearly 14 times in 35 years, from 0.863 square kilometers in 1986 to 11.947 square kilometers in 2021, and the greening speed has accelerated by 30% since 2016. As the temperature rises by nearly 3°C, the expansion of mosses may lay the foundation for the survival of other vegetation, but it may also make native plants lose competitiveness in the invasion of alien species, thus changing the Antarctic ecosystem.
The greening Antarctic Peninsula
The urgency of responding to climate change
Climate change is reshaping the earth's ecosystem. From the dullness of autumn leaves to the greening of the ocean to the expansion of Antarctic vegetation, these seemingly subtle changes reflect profound changes in nature. The familiar "autumn colors" may gradually disappear, and a "greening earth" is taking shape. Faced with this reality, we need to cherish nature more and take action to protect it. Climate change is an urgent issue at present, not a distant future.