What are the four levels in the ecosystem from largest to smallest?

The four levels in an ecosystem from largest to smallest are: biOSphere, which encompasses all living organisms on Earth; biome, which consists of specific regions with similar climate and ecosystems; ecosystem, which includes a community of living organisms interacting with their physical environment; and community, which is a group of different species living together in a specific area. These levels illustrate the complexity and interconnectedness of life on Earth.