Climate inertia

Climate inertia or climate change inertia is the phenomenon by which a planet's climate system shows a resistance or slowness to deviate away from a given dynamic state. It can accompany stability and other effects of feedback within complex systems, and includes the inertia exhibited by physical movements of matter and exchanges of energy. The term is a colloquialism used to encompass and loosely describe a set of interactions that extend the timescales around climate sensitivity. Inertia has been associated with the drivers of, and the responses to, climate change. Increasing fossil-fuel carbon emissions are a primary inertial driver of change to Earth's climate during recent decades, and vary based on the collective of its over 8 billion human inhabitants. Many system components have exhibited inertial responses to this driver, also known as a forcing. The rate of rise in global surface temperature (GST) has especially been resisted by 1) the thermal inertia of the planet's surface, primarily its ocean, and 2) inertial behavior within its carbon cycle feedback. Various other biogeochemical feedbacks have contributed further resiliency. Energy stored in the ocean following the inertial responses principally determines near-term irreversible change known as climate commitment. Earth's inertial responses are important because they provide the planet's diversity of life and its human civilization further time to adapt to an acceptable degree of planetary change. However, unadaptable change like that accompanying some tipping points may only be avoidable with early understanding and mitigation of the risk of such dangerous outcomes. This is because inertia also delays much surface warming unless and until action is taken to rapidly reduce emissions. An aim of Integrated assessment modelling, summarized for example as Shared Socioeconomic Pathways (SSP), is to explore Earth system risks that accompany large inertia and uncertainty in the trajectory of human drivers of change.