Earth’s Seasons and Climate Change
- Fiona Sridjaja
- Oct 13, 2023
- 3 min read
The four seasons
A season is a time of the year when the Earth’s axial tilt provides specific temperature and weather patterns that determine the climate in an area. There are four seasons in the Northern and Southern hemispheres including Spring, Summer, Autumn, and Winter. At the equator, there are limited climate variations. However, they are characterised by the dry season and the monsoon season.
One factor that significantly contributes to seasonal changes on Earth is the maximum intensity of exposed sunlight within a region. This changes throughout the Earth’s revolution around the sun and axial tilt relative to the orbital plane (where the Earth orbits the sun). The earth’s tilt causes the movement of the subsolar point, which determines the arrival of summer in the Northern or Southern hemisphere. The subsolar point is where the sun’s rays hit the Earth at a perpendicular angle constantly. The angle of sunlight narrows above and below the subsolar point. For example, although there are still four seasons in the North and South poles, the angle of sunlight is close to zero. During the Earth’s revolution, either hemisphere will tilt towards the sun, while the other tilts away from the sun.
Summer and Winter occur during the winter solstice and summer solstice respectively. In the Northern Hemisphere, the winter solstice begins on December 21 or 22, and the summer solstice occurs on June 20 or 21. The winter solstice is a time when daylight is shortest, and the summer solstice is when there is the longest period of daylight in a day. Moreover, Spring and Autumn seasons begin during equinoxes, which are days when the length of day and night are equal in all regions of the earth. The vernal or spring equinox is usually around March 20-21, and the autumn equinox is usually on September 22 or 23. These seasonal changes are important in vegetation growth and wildlife survival. They influence specific behavioural patterns of animals and periods of time for activity and rest.
The impacts of climate change
Climate change is the long-term shift in the Earth’s temperature and weather patterns that result in lasting consequences (Shaftel, 2023). They are increased due to human activities which increase the amount of greenhouse gases in the atmosphere, warming the Earth. One impact of climate change is the gradual change in the length and diversity of seasons. This article will mainly explore its recent effects in the Eastern United States.
October 2023’s Autumn!
This time of the year introduces the Autumn season, where a foliage of red and yellow hues spread out across the parks and forests. The cool breezes of air provide comfort to the warm sunlight. It is a well-anticipated time of the year. However, warmer temperatures have delayed the changing colour of leaves during this time. This may disrupt the “annual cycles of growth and rest that plants undergo” (Gibbens, 2021). Trees and other plants need rest after the activity during the Spring and Summer seasons, where they consistently photosynthesise to produce sugars and carbohydrates for respiration, and growth and development. The drop in temperature during the Autumn season allows the trees to absorb nutrients from leaves before letting them drop to prepare for Winter, in a process called leaf senescence. Before doing so, the leaves produce red anthocyanins in replacement of the green chlorophyll pigment to stave off the cold and absorb as much nutrients from the leaves as possible before they fall. Moreover, it may signal a more alarming potential of a forest collapse, as one out of five plant species found a century ago are no longer present.
Alongside a warming climate, the leaves also experience more damage due to pathogens and leaf-eating animals, which hasten the process of leaves falling from plants even before all their nutrients are absorbed from the Spring and Summer seasons. This suggests that fall is becoming shorter, and it shifts the arrival of other seasons as well, where Spring is occurring earlier. The lifespan of trees and other plants may also be affected, as these impacts may create changes in their growth during the following seasons.
Trees are vital in protecting the Earth from climate change as forests absorb approximately 30 percent of all carbon dioxide emissions released annually. Therefore, we should look to living sustainably and slowly reduce our carbon footprint, as these small habits shape the long-term trend that approaches the Earth.
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