The Origin of the Ice Age Reaction

Since the last ice age, the cause of climate change was originally thought to be ice calving in the Atlantic Ocean. However, a new study has shown that it occurred in the Pacific Ocean.

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By Jenny Chen

Imagine that a chunk of ice the size of multiple football fields broke off of an ice sheet and sank deep into the ocean, increasing displacement of ocean levels and flooding across the seven continents. This is what occurred during the end of the last ice age 11,000 years ago—a global climate change event where, according to the World Economic Forum, temperatures averaged 46 degrees Fahrenheit, about 10 degrees below today’s average temperature. The ice age ended with the breakage of ice sheets into the Atlantic Ocean, which scientists believe was responsible for climate change. However, new information sheds light on how changes in the Pacific Ocean were actually the cause of the latest ice age. This explains why there needs to be more research on past environmental events to ensure accurate data for the future of Earth’s dynamic climate.

To understand how the Pacific Ocean was one of the causes of climate change, it is important to understand the history of two planetary ice sheets and the ice-calving process. The Cordilleran and the Laurentide Ice Sheets were two ice masses that spanned east and west, respectively, of what is now Canada and Greenland. The two ice sheets were created through glaciation, where a combination of Earth’s lower tilt angle, orbit, and less heat from the Sun caused gradual accumulation of snow that turned into ice sheets. Later, a process known as ice calving caused several sections of the ice sheets’ borders to break off into their neighboring oceans. This process occured on such a massive scale that the world’s ocean levels greatly increased due to the ice chunks falling into water. Eventually, the Earth’s tilt angle increased due to gravity changes in the axes, causing an increase of temperatures that melted most of the ice sheets. Furthermore, the Laurentide Ice Sheet went through ice calving during the Heinrich events, further increasing the temperatures throughout Earth. Remnants of the Cordilleran Ice Sheet still exist, and scientists use them to discover new insights into the relationship between the ice age and global warming.

In a Science journal report published on November 6, 2020, Alan C. Mix, along with other scientists, argued that the western part of the Cordilleran Ice Sheet had a direct correlation with the ice calving in the Laurentide Ice Sheet. Through the analysis of specific sediment cores (layers of accumulated sediment that can give historical information) retrieved from the Gulf of Alaska, they were able to conclude that the ice calving in the Cordilleran Ice Sheet occurred shortly before the Heinrich events. Additionally, the study found that ice calving in the Cordilleran Ice Sheet correlates with the ice calving in the Laurentide ice sheet, suggesting that the calving of the West Cordilleran Ice Sheet in the North Pacific Ocean was the precursor to Heinrich events.

The exact details of the events between the West Cordilleran Ice Sheet calving and the Heinrich events are unknown, with several hypotheses having been proposed. One proposed by Mix discusses how the Cordilleran Ice Sheet chunk that melted into the Pacific Ocean eventually reached the Atlantic Ocean through Earth’s ocean currents. Since the chunk became freshwater, it created a blocking mechanism to the salt water in the Atlantic and theoretically would make the water near the Laurentide Ice Sheet warmer and trigger ice calving. Another possibility is that through the calving of the Cordilleran Ice Sheet, the planet’s surface winds would change and bring heat and moisture to the Laurentide Ice Sheet without being blocked. These two theories both offer explanations as to how heat was brought to the Laurentide Ice Sheet from the Cordilleran Ice Sheet through the Pacific Ocean. Confirming these theories would bring a better understanding of how ice calving, a process that occurs today at the polar caps, can dramatically change the environment of the Earth. Nevertheless, more research into ice sheets is needed to understand the process of how a single ice sheet caused a reaction of warming, possibly through more sediment core analysis of other ice remnants in North America.

The new developments on the Cordilleran Ice Sheet with the ice age illustrate why it is important to do further research on previously established studies. If we can study the causes of climate change through ice sheets, we can find ways of predicting the future as global warming continues to pressure the Earth. For example, we can help prevent destruction of agriculture and save lives. Therefore, the overall knowledge gained by the new data of the past allows us to assemble safety measures for future generations and ultimately understand the occurrences of dynamic shifts in climate change.