Climate Feedback Loops

Water Vapor Feedback

The strongest positive feedback. Warmer temperatures increase evaporation and atmospheric moisture capacity by about 7 percent per degree (Clausius-Clapeyron). More water vapor traps more heat, causing further warming. Satellites confirm moisture increasing at predicted rates. This approximately doubles CO2-only warming. Water vapor has short residence time (10 days) so it tracks temperature rather than being independently forced.

Ice-Albedo Feedback

Warming melts ice and snow, exposing darker surfaces. Snow reflects 80-90 percent of sunlight; ocean absorbs 94 percent. Less ice means more absorbed energy, more warming, more melt. Drives Arctic amplification (2-4x faster warming). September Arctic sea ice has declined roughly 40 percent since 1979.

Cloud Feedbacks

Most uncertain feedback. Low thick clouds cool (reflect sunlight); high thin clouds warm (trap infrared). Net effect depends on how cloud properties change with warming. Best estimate: weakly positive (about 0.5 W/m2/K), mainly from reduced low cloud cover as boundary layer warms. Major source of sensitivity uncertainty.

Carbon Cycle Feedbacks

Warmer oceans absorb less CO2 (lower solubility). Warmer soils decompose faster, releasing carbon. Permafrost thawing exposes frozen organics. Could add 50-200 ppm beyond emissions alone by 2100. Partially offset by CO2 fertilization of plants, though this effect saturates.

Lapse Rate Feedback

Weakly negative globally. Tropical warming amplified aloft (moist convection) radiates more efficiently to space. High-latitude warming concentrates near surface, radiating less efficiently. Net global effect slightly dampens warming.

Planck Response

Fundamental stabilizer preventing runaway warming. Warmer objects radiate more energy (Stefan-Boltzmann law, fourth power of temperature). All positive feedbacks operate against this background, ensuring new equilibrium rather than unlimited warming.