Polar Ice Caps: Temperature, Melting Effects & Facts

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Sarah Friedl

Sarah has a Master's degree in Zoology and a Bachelor's in Biology, and has taught college level Physical Science and Biology.

What are the polar ice caps? How do they regulate sea level and temperature on Earth? Polar bears aren't the only ones who should care about the melting of the polar ice caps - it's an issue that affects us all.

We also recommend watching Solar Energy: Effects on Earth's Temperature and Environmental Toxicants: Types, Sources & Effects

Definition

There is a lot of talk lately about the melting polar ice and its effects. But what is polar ice? And how does it affect our planet? A polar ice cap is a region of land at the North or South Pole of a planet that is covered with ice. Earth is not the only planet with polar ice caps - Mars also has them, though they are mostly frozen carbon dioxide.

Why are ice caps found at the poles? This has to do with the angle of sunlight reaching our round Earth. At the equator, sunlight hits the earth at a 90° angle. This creates an environment of little variation in both temperature and hours of sunlight during the day.

In contrast, sunlight hits the polar regions at a more indirect angle. The same amount of sunlight reaches this part of Earth, but it gets spread out over a larger area, so the area receives less solar energy. You can see this with a flashlight. If you hold a flashlight vertically over a flat surface, you create a round, bright circle. If you tip the flashlight so that it is not exactly vertical, the circle of light elongates and decreases the intensity of the light. This happens because the same amount of light is spread over a greater area.

This limited solar energy makes for cold temperatures and very little precipitation (either rain or snow) all year round, which helps maintain the polar ice caps. Polar ice caps and glaciers hold more than three-quarters of the earth's freshwater, and provide feeding and resting platforms for polar bears, seals, and marine birds.

Melting Polar Ice Caps

The melting of the polar ice caps is caused by the overall increase in global temperature, and this melting can have serious consequences for all organisms on Earth. Besides being important for marine life, ice caps help regulate sea level and global temperatures.

Sea Level

Imagine that you have a cup of water, and you place a large rock in the middle; the water is the ocean and the rock is a continent. If you place an ice cube on top of the rock, eventually it will melt into the 'ocean' around the rock, forcing water higher up around it. The same thing happens when polar ice caps melt. They melt directly into the ocean, increasing the volume of water, and forcing seas higher onto land.

Not only does the melting of the ice caps increase the volume of water in the oceans, it also decreases the salinity, or salt content. Polar ice caps are made of fresh water, so adding more fresh water without adding more salt makes the ocean water less saline. This can cause problems for organisms that are well adapted to the very salty ocean waters.

Temperature

It is very important that the polar ice caps are frozen, because the snow they are covered with reflects a large amount of light back into space that would otherwise increase the overall temperature of Earth. So you can see this is a serious problem - the polar ice caps help keep Earth a nice temperature, but the melting of polar ice caps increases the rate of global warming.

Maintaining the earth's temperature is very important to all the organisms that live in or around the polar ice caps. Despite being frozen and mostly covered with snow or ice, many small plants, invertebrates, and animals depend on the polar ice caps for food and shelter. Without the polar ice caps, many of these species would go extinct because they are well adapted to the climate and resources in these regions.

Polar ice cap melting also affects those who are very far from the polar regions. Without the ice caps, the middle United States would be several degrees warmer in the winter, preventing an annual freeze necessary for wheat growing. People in sub-polar regions are already being affected because fish, walruses, and seals are changing their migration patterns, which makes it difficult to hunt them.

Changes in Polar Ice Caps

Some seasonal variation occurs at the poles each year as the area of polar ice cover increases in the winter and decreases in the summer. However, the changes have been more significant in recent years. Summer decreases are hitting record lows, and the amount of accumulation in the winter is decreasing.

Changes in sea ice cover from 1979 to 2010
sea ice changes

The thickness of the ice caps is also changing. As the ice caps melt they not only cover less area but also become thinner. Usually, the core of the ice cap is what stays frozen all year long, because it is so thick. But as it becomes thinner, the core of the ice cap may not be able to stay frozen during summer months, creating a domino effect of melting.

The continued warming of Earth threatens the polar ice caps. These changes are becoming more rapid, and may not be reversible. Understanding the causes and monitoring these changes are the first steps to slowing the melting of the polar ice caps. However, we may not understand the full effects of melting polar ice caps until it is too late.

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