Natural systems are self-regulating entities that include both biotic (living organisms) and abiotic (non-living elements) components. Examples are water and carbon cycles.

Natural systems, in the context of Geography, most often refer to bio-geochemical cycles. These cycles represent the circulation and conservation of chemical elements and compounds within the biosphere.

The water cycle, also known as the hydrological cycle, is a natural system. It refers to the continuous movement of water on, above, and below the surface of the Earth.

Key processes in the water cycle include evaporation, condensation, precipitation, infiltration, surface runoff, and sub-surface return flows.

The carbon cycle is another example of a natural system. This refers to the flow of carbon (in various forms, such as carbon dioxide) through the atmosphere, ocean, terrestrial biosphere and lithosphere.

Key processes in the carbon cycle include photosynthesis, respiration, decomposition, natural weathering of rocks, volcanic activity, and human activities like burning fossil fuels.

Natural systems, such as the water and carbon cycles, are dynamic and interactive with fluctuations and changes in one system often affecting the other.

Natural systems are crucial for maintaining life on Earth, providing resources, regulating climate, and supporting diverse ecosystems.

It is essential to understand the mechanisms of these cycles and the impacts of human activities on them to sustainably manage natural resources and mitigate environmental issues such as climate change.

Both the carbon and water cycle are heavily impacted by human-induced climate change and are fundamental to climate change science. For instance, increased carbon dioxide in the atmosphere due to the burning of fossil fuels influences the water cycle by changing precipitation patterns and temperatures.

Feedback mechanisms in natural systems can either magnify (positive feedback) or reduce (negative feedback) changes to the system. Examples include the ice-albedo feed-back loop in the arctic and the carbon sequestration by forests.

In the context of geography, understanding natural systems is vital because these systems influence climate, weather patterns, soil fertility, and lifeforms.