Global Change and Climate in the Earth System — Causes, Cycles, and Human Impact | Chapter 23 from Earth: Portrait of a Planet
Global Change and Climate in the Earth System — Causes, Cycles, and Human Impact | Chapter 23 from Earth: Portrait of a Planet How do global forces shape our planet’s past, present, and future? Chapter 23 of Earth: Portrait of a Planet by Stephen Marshak explores the profound topic of global change, tracing both natural cycles and the accelerating effects of human activity. For a concise audio-visual summary, watch the chapter video on YouTube , or read below for a complete guide to the science behind Earth system transformation. Unidirectional and Cyclic Change in Earth’s History Unidirectional Changes: Irreversible transformations such as the Moon’s formation, planetary differentiation, evolution of continents, development of the atmosphere, and the emergence of life. Cyclic Changes: Recurring processes including the supercontinent cycle, sea-level rise and fall, the rock cycle, and biogeochemical cycles (carbon, hydrologic). The Carbon Cycle and Greenhouse Effec...