If an adaptive system is getting pushed hard enough, its defense systems can switch from negative to positive runaway feedback. (planet3.org)
These are not runaway feedbacks, but together they strongly amplify the impacts in polar regions of a positive (warming) climate forcing... Augmentation of peak Holocene temperature by even 1C would be sufficient to trigger powerful amplifying polar feedbacks, leading to a planet at least as warm as in the Eemian and Holsteinian periods, making ice sheet disintegration and large sea level rise inevitable.» (climatecodered.org)
So that the median lines are the shared pathway of the EMF that is controllably shunted out of the chemical reaction to allow the flexible shifts in efficiency needed to prevent uncontrolled runaway feedback or disease processes that cause death. (wattsupwiththat.com)