How important is equilibrium to the environment?
Equilibrium can indicate a good point an environment can be to be sustainable. Using the Artice sea ice as an example, when in a sustainable equilibrium, temperatures are lower, more sea ice is present, and the ice reflects solar radiation; when shifting away from equilibrium and towards collapse, temperatures are higher, little to no ice is present, solar radiation is absorbed.

What are the different stable of equilibria?
There are two types of stable equilibria: the virtuous cycle and the vicious cycle. The virtuous cycle occurs at high equilibrium, when the S-shaped environmental dynamics curve intersects at the highest point it can on a 45-degree line; here more ice in the sea will reflect away more radiation to keep temperatures low, which keeps the ice from melting, inducing a feedback loop. Contrary, a vicious cycle occurs at the lowest point of intersection; here, less ice allows more absorption of radiation, warming up the weather, inducing more ice to melt, and creating a feedback loop.

What is an unstable equilibrium?
There is also an unstable equilibrium that occurs at the intersection point between the other two equilibria, the tipping point. If unusually hot years occur one after another and the amount of ice is now below a certain amount, the initial reduction of sea ice from hot weather is amplified, causing further reduction until no ice is left.

How may policies use the tipping point to protect the environment?
Policies can try to maintain the EDC in the set of feasible environmental equilibria, ensuring that the tipping point is not passed. These prudent policies are implemented because there is uncertainty surrounding the tipping point itself, the degree of shocks that would push the environment past the tipping point, and severe risks could occur otherwise.

What is an example of a prudential policy?
An example of a prudential policy might be one that accounts for environmental variables such as temperature or biodiversity loss and the degree of maintenance to avoid surpassing the tipping point.

What do current trends indicate about Arctic sea ice?
Though the ice was in high equilibrium before the 60s, the amount of ice would eventually decline gradually and then rapidly, indicating the passing of the tipping point.

How may a policymaker use prudence to determine what policies to pass?
Assuming there was certainty surrounding the state of the environment and the effect of tax incentives, tax on carbon emissions or cap and trade policy would yield the same desired level of abatement. However, cap and trade policies are typically more prudent as they have a set limit, which could be set far below the threshold.

Equilibrium: something that is self-perpetuating and does not change unless outside forces act on it

Environmental tipping point: a point on a graph where self-limiting environmental

degradation processes become positive feedback loops of perpetual degradation

Environmental dynamics curve: curve that measures varying states of the environment in a given period

Tipping point: a point of unstable equilibrium

Prudential policy: highly values reducing likelihood of disastrous outcome

Equilibrium is crucial for the environment as it represents a sustainable state. In the context of Arctic sea ice, being in equilibrium means lower temperatures, more sea ice reflecting solar radiation, and a stable environment. When shifting away from equilibrium towards collapse, temperatures rise, ice melts, and solar radiation is absorbed. There are two types of stable equilibria: virtuous cycle and vicious cycle. The virtuous cycle occurs at high equilibrium, where more ice reflects radiation, maintaining low temperatures and preventing further melting. The vicious cycle occurs at low equilibrium, where less ice leads to increased absorption of radiation, higher temperatures, and more melting, creating a feedback loop. An unstable equilibrium, known as the tipping point, exists between the two stable equilibria. If the amount of ice decreases below a certain threshold due to consecutive hot years, the initial reduction is amplified, leading to further melting until no ice remains. Policies can use the tipping point to protect the environment by aiming to maintain the system within the feasible environmental equilibria. Prudent policies are implemented due to uncertainty surrounding the tipping point, potential shocks, and the associated risks of surpassing it. A prudential policy example could involve considering environmental variables like temperature or biodiversity loss and implementing measures to prevent surpassing the tipping point. Current trends indicate a decline in Arctic sea ice since the 1960s, suggesting the passage of the tipping point. The ice was initially in high equilibrium but has gradually and rapidly decreased over time. A policymaker can utilize prudence to determine which policies to implement. Assuming certainty about the environmental state and the effectiveness of tax incentives, both a tax on carbon emissions and a cap and trade policy would achieve the desired level of abatement. However, cap and trade policies are typically considered more prudent as they set a specific limit, which can be set below the threshold to ensure greater environmental protection.

An example of policies made to preserve the equilibrium of an environment and prevent further damage is the Artic Council which is set up to overlook certain activities occurring in the Artic Sea.