Arctic ice

The Arctic and Antarctic are vastly different places. But these polar regions do have something in common: As climate change transforms these areas, people all over the world – even many thousands of miles away – will face the effects.

As land ice melts from the Greenland ice sheet and from Antarctica, rising seas are threatening coastal cities and low-lying nations. Here’s what you need to know about these critically important areas of the planet.

1. Polar bears live in the Arctic. Penguins live in the Antarctic.

The Arctic refers to the area around the North Pole. Polar bears live in some regions of the Arctic, which is largely ocean covered with sea ice. The 656,000-square-mile Greenland ice sheet, on the island of Greenland, is located largely within the Arctic Circle.

In contrast, the Antarctic contains the South Pole and is where penguins live. Antarctica is a continent with a massive 5.4-million-square-mile ice sheet. Sea ice forms around the continent.

Antarctica is far colder than the Arctic. South Pole Station records an average temperature in the winter of -76 degrees Fahrenheit, while the North Pole is practically balmy at -40 degrees Fahrenheit. During summer, the South Pole averages -18 degrees Fahrenheit compared to the North Pole’s 32 degrees Fahrenheit – the temperature at which ice melts.

Because Antarctica is essentially an island surrounded by ocean, it is subject to different weather patterns than the Arctic – which is, conversely, an ocean surrounded by land. But the effects of climate change in both regions are significant.

2. Melting land ice could swamp the world’s coastlines.

Land ice generally refers to glaciers and ice sheets, while sea ice floats in the ocean. Massive ice sheets – land ice – cover much of Greenland and Antarctica. Combined, these two enormous slabs of ice hold over 99 percent of the Earth’s freshwater ice.

Greenland’s ice sheet is melting rapidly, and NASA reports that Antarctica’s melting ice sheet makes up 20 to 25 percent of current sea-level rise (see here and here).

In the Arctic, sea ice is also melting. September is the month with the smallest amount of Arctic sea ice, called the “sea ice minimum.” Scientists compare annual September Arctic sea ice measurements to learn about the rate of decline. Right now, it is decreasing 12.8 percent each decade.

The status of Antarctic sea ice is more nebulous. While there has been a slight increase in Antarctic sea ice overall since satellite tracking began in 1979, the increase is not statistically significant.

3. The ‘albedo effect’ hastens melting in polar regions.

On a hot day, the temperature in a black car with black leather can soar to life-threatening levels. On the same day, a light-colored car with light-colored interior will feel significantly cooler (although still a life-threatening risk to anyone, in particular children, long inside.) The reason: Dark colors absorb more solar energy, while lighter colors reflect more.

The term “albedo” refers to how well something reflects the Sun’s energy. Scientists measure albedo on a range between 0 (black) and 1 (white). The albedo of sea ice is generally 0.5 to 0.7, which is much higher than the ocean (usually around 0.06). As a result, sea ice reflects far more solar energy than the ocean, helping it stay cooler. Snow on sea ice can bring the albedo up to 0.9, which keeps it even colder.

But when snow and sea ice start to melt, the albedo drops quickly. Melt ponds have a much lower albedo than sea ice or snow, which means they absorb more solar energy and melt faster.* That rapid melting leads to creation of more ponds of melted ice and snow, which increases the area’s albedo and exacerbates the warming even more. It is a vicious cycle.

The albedo effect is a major driver of temperature change in the Arctic. The region is warming at more than double the rate observed anywhere else on the planet.

4. Even if you live far from the poles, changes in these regions could affect you.

People who live thousands of miles from the Arctic and Antarctic will face the impacts as ice melts.

Scientists say that if the Greenland ice sheet were to completely melt, global sea levels would rise 20 feet – high enough to eliminate major cities around the globe and some low-lying atoll nations. However, even that drastic impact seems minimal compared to the sea-level rise if the Antarctic ice sheet were to melt. It would take a long time, but eventually, nations would be drastically altered – and some wiped off the map – as seas rise by 200 feet.

This NASA map of Florida shows just how much land would be underwater if the sea were to rise just a few feet, completely reshaping the state. With so many low-lying communities hugging coastlines, the impact would be dramatic in areas far from the polar regions.

5. An ice-free Arctic could change navigation.

Melting sea ice means more than just submerged cities. As ice melts and previously impenetrable northern sea routes open up, ships could make their way through these areas during certain times of year – or perhaps eventually all year long. Traversing these areas could be a short cut for tankers and other ships, and these routes could open up opportunities for tourism, which has already begun. The Crystal Serenity, a luxury cruise ship, transited the Northwest Passage in 2016 and 2017.

Some nations are also analyzing the economic costs and opportunities of these passages opening. Shipping times could eventually decrease, but the times when the routes will be navigable will be unpredictable, at least at first. This uncertainty – combined with the cost of building reinforced ice-breaking ships for the journey and the potential for getting stuck or requiring rescue – means it may be a while before the route makes financial sense for shipping companies.

More ship traffic in Arctic waters will have implications for ecosystems, economies, and national security. An accident or oil spill could pollute Arctic waters, and increased vessel traffic could harm fragile wildlife such as narwhals. So routine navigation in the Arctic, when it begins, will have profound implications for this remote area of the planet … and for the planet as a whole.

AUTHOR
Kristen Pope is an Idaho-based freelance writer who frequently covers science and conservation-related topics.

*This sentence was updated 7/10/19 to reflect the fact that melt ponds have a lower albedo than snow and ice, not higher.

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