Discussion of specific items in Table 1 conveys some of the complexity of the systems involved. For instance, permafrost thawing is part of a potentially rapid, nonlinear feedback system that influences GCC both as an outcome of an effector and an effector itself. Permafrost covers approximately one-fourth of the earth’s landmass and contains nearly double the atmospheric mass of carbon. Many permafrost areas are receding. As they melt, they release CO2 and CH4. These greenhouse gases induce further atmospheric warming, which could accelerate permafrost melting and release more greenhouse gases. Increased temperatures would result, potentially yielding a runaway feedback process [9].