Climate inertia is the phenomenon by which climate systems show resistance or slowness to changes in significant factors, such as greenhouse gas levels. In the context of climate change, this means that mitigation strategies, such as the stabilization of greenhouse emissions, might show a slow response due to the action of complex feedback systems. As a specific example, melting ice sheets in Greenland and Antarctica take time to respond to the emissions of fossil fuel carbon in the climate system. Global warming also causes thermal inertia, thermal expansion of the oceans, which contributes to sea level rise, and it has been estimated that we are already committed to a sea-level rise of approximately 2.3 meters for each degree of temperature rise within the next 2,000 years.
The ocean’s thermal inertia delays some global warming for decades or centuries. It is accounted for in global climate models, and has been confirmed via measurements of Earth’s energy balance. Permafrost takes longer to respond to a warming planet because of thermal inertia, due to ice rich materials and permafrost thickness.
The observed transient climate sensitivity and the equilibrium climate sensitivity are proportional to the thermal inertia time scale. Thus, Earth’s equilibrium climate sensitivity adjusts over time until a new steady state equilibrium has been reached.
Ice sheet inertia
Even after CO
2 emissions are lowered, the melting of ice sheets would continue, and further increase sea-level rise for centuries. The slow transportation of heat into the oceans and the slow response time of ice sheets will continue until the new system equilibrium has been reached.
Depending on the ecosystem, effects of climate change could show quickly, while others take more time to respond. For instance, coral bleaching can occur in a single warm season, while trees may be able to persist for decades under a changing climate, but be unable to regenerate. Changes in the frequency of extreme weather events could disrupt ecosystems as a consequence, depending on individual response times of species.
Policy implications of inertia
The IPCC concluded that the inertia and uncertainty of the climate system, ecosystems, and socioeconomic systems implies that margins for safety should be considered. Thus, setting strategies, targets, and time tables for avoiding dangerous interference through climate change. Further the IPCC concluded in their 2001 report that the stabilization of atmospheric CO
2 concentration, temperature, or sea level is affected by:
- The inertia of the climate system, which will cause climate change to continue for a period after mitigation actions are implemented.
- Uncertainty regarding the location of possible thresholds of irreversible change and the behavior of the system in their vicinity.
- The time lags between adoption of mitigation goals and their achievement.