What is the primary source of energy for Earth's ecosystems?

The Sun is the primary source of energy for Earth's ecosystems because it provides the necessary light and heat for processes like photosynthesis, which is fundamental to life on Earth. During photosynthesis, plants, algae, and some bacteria convert sunlight into chemical energy, creating organic matter that serves as food for a wide range of organisms. This process not only supports the producers but also forms the base of the food web, influencing the dynamics of all living communities.

Without the Sun’s energy, the Earth would not support the vast diversity of life we see today, as other options like the Moon, wind, and water currents do not supply the fundamental energy required for photosynthesis. Instead, these elements interact with solar energy in various ways or can contribute to energy transfer after it has been generated by plants and other primary producers.