NEWS: Thawing permafrost in Alaska is releasing acids + metals, turning rivers orange and altering water chemistry.

ABOUT PERMAFROST

• Ground that remains frozen at 0°C or below for at least 2 consecutive years.
• Found mainly in → high latitudes + high-altitude regions.
• Can occur → on land + beneath the ocean floor.
• Contains → soil + rocks + sand held together by ice.

ACTIVE LAYER

• Surface soil layer above permafrost.
• Thaws during summer + freezes again in winter.
• Usually thin in colder regions.

IMPACTS OF THAWING

• Greenhouse gases → releases carbon dioxide + methane.
• Positive feedback → warming → thawing → greenhouse gas release → further warming.
• Ground instability → damages roads, buildings + pipelines.
• Water pollution → releases mercury, acids + other contaminants.
• Biodiversity/health → may release dormant microorganisms.
• Ecosystem impact → changes soil, vegetation + water chemistry.