The main feedbacks from the Arctic are:
- Changes in air circulation – much of the world’s weather is driven by differences between equatorial heat and polar cold. As the Arctic warms, the differences in temperature are not as great as they were, and that affects weather patterns including storm patterns and rainfall.
- Changes in water currents – just as the air moves heat between the equators and the poles, so do the oceans, although ocean currents are also affected by the saltiness of the water. As ice melts in the Arctic, it makes the water less salty, creating changes in the currents.
- Increases in greenhouse gases – arctic soils and wetlands contain twice the amount of carbon currently in the atmosphere. As the Arctic warms, carbon that has been frozen and locked in for thousands of years starts to be given off as methane and carbon dioxide, adding to the greenhouse gas burden in the atmosphere, and further increasing climate change.
- Sea level rise – the melting of the Greenland ice cap and other polar sources are now thought to contribute to raising global sea levels by more than a metre within a hundred years, affecting a quarter of the world’s people.
Taken together, these feedbacks have the capacity to create profound global changes in food supplies, severe weather events, and water supplies.
