According to NOAA, positive feedback loops are systems where an initial process effects changes in a second process, which then increases the effects of the initial process. The loops continue in a vicious cycle.

Some examples of positive feedback loops:

• Warming oceans - Oceans serve as a carbon sink, absorbing carbon dioxide and storing it in the water. Because of this, oceans are an important part of managing carbon levels in the atmosphere. However, the more carbon dioxide that gets stored in the ocean, the warmer the ocean gets, the less carbon dioxide it is able to store, the more carbon dioxide in the atmosphere.

• Melting glaciers - When sunlight hits a surface, that surface reflects some of that light back into space. The amount of light that gets reflected back is called albedo. Snow and ice in the Arctic and Antarctic play a critical role in reflecting sunlight back into space, preventing the planet from warming too much. According to NASA, ice reflects 50--70% of sunlight, while snow can reflect as much as 90% of sunlight. However, as the Earth gets warmer (from other factors such as greenhouse gases), the Arctic and Antarctic start to melt, the reflective surfaces start disappearing, more sunlight stays in the Earth's atmosphere, the Earth gets warmer.

• Thawing permafrost - Permafrost is permanently frozen ground. A lot of our existing permafrost was formed thousands of years ago, and much organic matter (such as plants) are stored in permafrost, kept from decomposing by the cold temperatures. As the Earth warms, permafrost thaws, creating pools of water in which anaerobic bacteria (bacteria that doesn't need oxygen to survive) decompose matter and release carbon dioxide and methane. This carbon dioxide and methane warms the atmosphere, which thaws more permafrost, which releases more carbon dioxide and methane.*

• Water vapor - Water vapor is a greenhouse gas, which means it warms the Earth. It's the only greenhouse gas that amplifies its own effects through a positive feedback loop. When air gets warmer, it is able to hold more water vapor (think of a humid day). When the air holds more water vapor, it gets warmer.

*thawing permafrost also leads to unstable ground, which causes houses, roads, etc. to collapse. Some communities that live on permafrost have already had to be relocated.