What is the primary source of energy for life on Earth?

The primary source of energy for life on Earth is sunlight. Sunlight is harnessed by plants through the process of photosynthesis, where they convert light energy into chemical energy stored in glucose and other organic molecules. This process not only sustains the plants themselves but also provides energy for the entire food web. Herbivores consume the plants, obtaining the energy stored in them, and carnivores then consume these herbivores, transferring energy through the ecosystem.

In addition to sustaining the primary producers, sunlight also drives various processes that are crucial for life, such as the water cycle and weather patterns. Without this solar energy, ecosystems would collapse, and life as we know it would not be sustainable.

Water, while essential for life as a solvent and medium for biochemical reactions, does not provide energy. Similarly, soil nutrients are necessary for plant growth and various metabolic processes but do not serve as a direct energy source. Wind is a form of energy that influences weather and erosion but is not a primary energy source for biological processes. Thus, sunlight is unequivocally the foundational energy source crucial for life on Earth.