Why Do Ice Ages Happen?
Wed, April 21, 2021

Why Do Ice Ages Happen?

The Earth has undergone at least five major ice ages in the 4.6 billion years since our planet was formed, each having a profound impact on our climate / Photo by: Standret via Shutterstock

 

The Earth has undergone at least five major ice ages in the 4.6 billion years since our planet was formed, each having a profound impact on our climate. While scientists have found that they were driven by the changes in the Earth’s orbit, they are still trying to understand how the climate system is involved, particularly greenhouse gases. 

The last ice age happened during the Pleistocene Epoch, which began about 2.6 million years ago and lasted until about 11,700 years ago. According to Live Science, a news website that features groundbreaking developments in science, space, technology, health, the environment, our culture, and history, during the Ice Age, sheets of ice covered all of Antarctica, North America, South America, large parts of Europe, and small areas in Asia. Its remains can still be seen in some parts of the world, including Antarctica and Greenland.

An ice age causes huge changes to the Earth’s surface. Glaciers reshaped the landscape and a dramatic drop in sea levels caused rivers to carve out deeper valleys and produce enormous inland lakes. Life for species in the past was difficult. While large mammals died of the harsh climate conditions, some managed to thrive. These animals include macrauchenia (similar to llamas and camels) and tenrecs (hedgehog-like creatures). 

During the ice age of the Pleistocene Epoch, around 30% of the Earth’s surface was covered with ice. The entire surface of the planet has also been smothered in ice a few times, earning it the moniker “snowball earth.” This is because it resembled a massive woolly ball of snow when observed from space. A perfect example of this is the Sturtian/Marinoan glaciation which happened about 710 to 640 million years ago.

According to scientists, this particular ice age saw continental glaciations on such an unprecedented scale that even regions around the equator had massive glaciers. Ice ages begin when a drop in temperature prevents snow from fully melting in some areas. This means that ice ages take thousands of years to begin.

What Causes an Ice Age?

Dr. Steven Phipps, an ice sheet modeler, stated that they gathered evidence of ice ages through looking at corals, coral reefs, and the past sea-level changes in the tropics. According to History, an online site that features thousands of historical articles and videos, scientists have recorded five significant ice ages throughout the Earth’s history. These are the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present). 

Aside from these five major ice ages, the Earth has also experienced a dozen major glaciations over the past one million years. Initially, scientists thought that ice ages occurred due to wobbles in the Earth’s orbit which changed the distribution of solar energy on the planet’s surface, prompting the ice age cycles. A 1941 study by Serbian climatologist Milutin Milankovitch believed that the Earth had produced an ice sheet because there was less insulation during the summer months. As a result, the average temperature was slower, which paved the way for ice to survive and build up. 

However, geologist Louis Agassiz and mathematician Milutin Milankovitch provided a different explanation about three decades later. According to them, an ice age can be started once factors like regular changes in the Earth's tilt and orbit align in a way that the northern hemisphere gets less solar radiation in summer. Milankovitch added that orbital conditions for cool summers have been critical aspects of ice ages. “You’re always going to have ice in winter. To build an ice age, you need to have some of that ice survive through the summer,” he said. 

But, an orbital phenomenon usn’t the only factor the can trigger an ice age. Mark Maslin, a professor of paleoclimatology at University College London, stated that the fundamental feedback in the climate system and various environmental factors can influence glaciation and deglaciation. Recent studies also suggested that greenhouse gas levels in the atmosphere play an integral role. Scientists at the Potsdam Institute for Climate Impact Research (PIK) in Germany revealed that past ice ages were mainly triggered by both the dramatic increase and decline of carbon dioxide in the atmosphere because of human-caused emissions. 

Hans Joachim Schellnhuber, then-director of PIK and a co-author of one of those studies, described how ice ages have shaped the global environment, determining the development of human civilization. "For instance, we owe our fertile soil to the last ice age that also carved out today's landscapes, leaving glaciers and rivers behind, forming fjords, moraines, and lakes. However, today it is humankind with its emissions from burning fossil fuels that determines the future development of the planet,” he said. 

Aside from these five major ice ages, the Earth has also experienced a dozen major glaciations over the past one million years / Photo by: mrteeyai via Shutterstock

 

When Will the Next Ice Age Happen?

With the current status of climate change and its worsening impacts, scientists stated that there is a possibility that a mini ice age might happen around 2030. Some of the major factors include the increasing levels of greenhouse gases and the rising global temperature. Unfortunately, this would cause huge consequences for human civilization. 

According to ABC, Australia's international television service, an ice age can cause huge regions to become completely uninhabitable. All of these places are projected to be covered in thick ice sheets and subject to an inhospitable climate. Aside from that, there would be a lot less agricultural land available to humans, altering the entire Earth’s landscapes.

Indeed, ice ages are scary to think of because it would mean that millions of humans and species will die. Thus, addressing the major causes of this phenomenon can prevent this from happening. 

With the current status of climate change and its worsening impacts, scientists stated that there is a possibility that a mini ice age might happen around 2030 / Photo by: Frank Wasserfuehrer via Shutterstock