Figure 8.25: Decline of Arctic Summer Sea Ice

Ice-Albedo Positive Feedback

Figure 8.27: Environmental Dynamics, Multiple Equilibria, and the S-Shaped EDC

Ongoing Transition to a Low-Ice Arctic Equilibrium

Scientific Uncertainty on the Reversibility of Arctic Ice Loss

Consider two possible states for a large, ice-covered polar ocean. In 'State A', the ocean is almost completely covered by highly reflective ice, which bounces most sunlight back into space, keeping the region cold and preserving the ice. In 'State B', much of the ice has melted, exposing darker ocean water that absorbs sunlight, which in turn warms the water and causes even more ice to melt. What is the most critical difference in the underlying environmental dynamic between these two states?

Imagine a region of the Arctic Ocean that has experienced a significant reduction in its summer sea ice cover due to a period of unusually warm years. Arrange the following events into the correct causal sequence that describes the self-reinforcing cycle that could prevent the ice from recovering, even if temperatures returned to their previous average.

Critique of an Arctic Restoration Proposal

Evaluating a Policy Statement on Arctic Ice Recovery

Dynamics of Polar Ice Stability

Match each environmental component or dynamic with its correct description in the context of a large, ice-covered polar ocean system.

Statement: If the external factors causing initial warming were completely removed and global temperatures returned to their historical average, the extent of summer sea ice in the polar regions would naturally and rapidly return to its previous, larger state because the system's original stabilizing mechanisms would take over.

Persistent Ice Melt Scenario

A large, historically stable ice-covered lake on a fictional planet experiences a temporary increase in atmospheric dust from volcanic eruptions. This dust darkens the ice surface for several years. After the dust settles and the ice is white again, scientists observe that the lake's ice cover continues to shrink each summer, more than before the volcanic event, even though the planet's average temperature has returned to its previous level. Which of the following best explains why the lake's ice cover continues to shrink after the initial disturbance is gone?

Interpreting Climate Model Simulations for a Frozen Lake