What is meant by a glacier surge? What do scientists think produces surging episodes?

When delving into the study of glacier surges, one must understand glacier dynamics - the intricate movements and behaviors of glacier ice as it flows and evolves over time. A glacier behaves much like a slow-moving river of ice, gradually deforming and shifting due to gravity. This flow is generally slow and steady, but it can experience jolting changes during a surge event.

Factors contributing to glacier dynamics include the ice's temperature, the glacier's size and shape, the slope of its bed, and the presence of water at the boundary between ice and rock. These dynamics are crucial for comprehending the natural ebb and flow of glaciers and for predicting the impact of surges on glacial landscapes and sea-level change.
Surges can lead to significant advances of glacier fronts, posing potential hazards to nearby communities and landscapes. By studying glacier dynamics, scientists can better forecast these events and mitigate their implications.

The thermal regulation theory is fundamental to explaining glacier surges. It suggests that fluctuations in temperature at the glacier base initiate a surge. Here's a simplified rundown:

A glacier's base temperature can warm due to frictional heat generated by ice movement or other external factors. Upon warming, ice at the glacier's base starts to melt, creating meltwater that acts as a lubricant, reducing friction, and allowing the glacier to slide over its bed more freely. Consequently, this process increases the glacier's velocity. However, as the glacier speeds up, it draws colder ice down from above, which can cool the base again, decreasing meltwater production and subsequently slowing the glacier’s progress.

Over time, the pressure from the accumulation of ice above can cause the glacier to warm again, repeating the cycle. This theory underscores the importance of temperature variations in the overarching mechanisms of glacier movement.

Glacial geomorphology is the study of landforms created by the action of glaciers and the processes involved in sculpting them. These processes include erosion, transportation, and deposition of materials as a glacier advances and retreats.

A surge can dramatically alter the landscape, quickly carrying vast amounts of rock and sediment and reshaping valleys into characteristic U-shapes, forming moraines, drumlins, and other glacial features. These physical transformations provide geologists with clues about past climate conditions and glacial behavior. Understanding the language of these landforms is crucial for interpreting Earth's environmental history and projecting future changes in an era of climate fluctuation.

Geothermal activity, the natural heat emanating from within the Earth, also plays a significant role in glacier surges. Areas with heightened geothermal heat flux can warm the base of glaciers, contributing to the creation of meltwater that lubricates the glacier bed, similar to what is described in the thermal regulation theory.

Geothermal hotspots can lead to localized zones where glacier ice moves faster than in surrounding areas. This increased melting can potentially drive a glacier into surge conditions if it interrupts the glacier’s thermal and mechanical balance. It is a less common but essential factor to consider when examining the overall health and behavior of glaciers, encompassing both the immediate and long-term consequences of geothermal heat on glacier stability and flow patterns.