Feedback loops and Earth system change

Because Earth's geosphere, hydrosphere, atmosphere, and biosphere are linked, one change can set off a chain of changes in the others, and scientists use data to trace these connections. A feedback is a response that loops back to affect the change that caused it. A positive, or amplifying, feedback strengthens the original change: warming melts snow and sea ice, exposing darker land and ocean that absorb more sunlight and cause more warming (the ice-albedo feedback); warmer air holds more water vapor, itself a greenhouse gas (the water vapor feedback); and thawing permafrost can release carbon dioxide and methane. A negative, or stabilizing, feedback weakens the original change: over hundreds of thousands to millions of years, higher carbon dioxide levels and warmer, wetter conditions speed up the chemical weathering of rock, which removes carbon dioxide from the air and cools the planet, acting as a slow thermostat. Many changes cascade through several systems: clearing forests reduces the water plants return to the air, which can lower rainfall and increase erosion, and building a dam traps sediment, which starves downstream beaches and deltas and changes river ecosystems. Because several feedbacks act at once, the overall result depends on their combined strength, which is why scientists measure them carefully with satellite and field data.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report