Thinning of the Arctic Ice Cap | Ecology Global Network

The Arctic sea ice is providing clues to the Earth's overall climatic condition. Image: NASA

The geographic North Pole was last covered with water about 50 million years ago, during the early part of the present Cenozoic Era. Known as the Age of Mammals and the Recent Life Era, this modern age, which saw the dawn of human beings, began 65 million years ago.

During the Cenozoic Era, the continents which formed Pangea, the super continent, had begun to move into their present positions. As these continents drifted northward, they formed the shoreline of the Arctic Ocean, which lies directly over and around the geographic North Pole.

Formation of the Ice Caps

About 15 million years into the Cenozoic Era, the Arctic Ice Cap formed over the Arctic Ocean, virtually covering the entire sea with a sheet of ice. As the continents continued to move, climatic changes, brought about by shifts in water and air currents, caused the Earth to gradually cool down. This created the glaciers that mostly dominated the land masses through the end of the Great Ice Age in the Pleistocene Epoch, about 10,000 to 1.8 million years ago These glaciers still exist today on Greenland.

The same climatic conditions that created the glaciers, which are essentially great ice sheets formed on land, also formed the Arctic Ice Cap. Yet the ice sheet covering the Arctic Ocean rests directly on top of the ocean instead of land, and it has remained relatively stable and frozen since it was formed… until now.

The Arctic Ice Cap is shrinking dramatically. Roughly the size of the United States, it has lost an area roughly the combined size of Massachusetts and Connecticut each year since the late 1970s. Since the 1950s, when data was first collected on the Arctic, the ice cap has lost nearly 22 percent of its volume. It is projected that in another 50 years, nearly half of the Arctic Ice Cap will be gone.

Melting Caps

This chart compares the actual loss of Arctic Ice Cap volume between the 1950s and 2000, and the projected loss by 2050. The more ice that is lost, the faster the ice cap shrinks due to the loss of albedo, the amount of light energy that is normally reflected back out into space by the ice cap. Image: NOAA

So what is going on? We know that the Arctic Ice Cap, frozen for 50 million years, is melting. We also know that above normal Arctic temperatures, from the ocean water to the air currents, account for the melting. Global warming is real, and the melting of the Arctic Ice Cap is one of its symptoms.

According to NOAA scientists, 2010 tied with 2005 as the warmest year of the global surface temperature record, beginning in 1880. This was the 34th consecutive year with global temperatures above the 20th century average. For the contiguous United States alone, the 2010 average annual temperature was above normal, resulting in the 23rd warmest year on record.

The National Aeronautics and Space Administration’s (NASA) 2008 Surface Temperature Analysis shows:

Since the mid 1970s, the average surface temperature has warmed about 1 F.
The Earth’s surface is currently warming at a rate of about 0.29 F/ decade or 2.9°F/century.

IceSAT Satellite photos showing how warming reduced the thickness of Arctic ice between 2004 and 2008 Courtesy of NASA

Using the best available data, many scientists believe this warming trend will cause an additional 5-10 F increase in the average global temperature in the next century. Still, there are many scientists who believe the global warming trend may reverse itself within the next century. The fact is, there is not enough known about why the climate is changing the way it is for scientists to determine what really is going on or what will happen in the future.

We Know a Lot

Human activity, such as the burning of fossil fuels, is releasing enormous volumes of carbon dioxide and other greenhouse gases that are contributing to the Earth’s natural greenhouse effect the Earth’s natural process of trapping the sun’s warmth. Additional billions of tons of carbon dioxide are emitted each year due to human activity. This results in more heat being trapped within the Earth’s atmosphere;

The Polar Ice Cap itself reflects sunlight energy (heat) back into space, rather than the heat being absorbed by the Earth. This is called albedo, the amount of sunlight reflected by an object. As the Ice Cap melts, the albedo is reduced and the Earth absorbs the energy that is not reflected. Thus, the Arctic retains more heat.

The Earth’s natural carbon cycling process, the amount of carbon dioxide that enters and leaves the atmosphere as a result of the natural cycle of water exchange from and back into the sea and plants, accounts for about 95 percent of the carbon dioxide in the atmosphere, which contributes to the greenhouse effect;

Ocean waters constantly move along a giant oceanic conveyer belt which travels from the North Atlantic to the Atlantic, Pacific and Indian Oceans. This circulation distributes warm tropical waters northward, which are then chilled and returned to the warmer southern oceans. This heat exchange also has a significant impact on global weather patterns. Image: NASA

Ocean waters are constantly on the move, carrying warmer waters north toward the Arctic and cooler waters south to the temperate and tropical zones. This ocean circulation is referred to as the great oceanic conveyer belt, which is a single continuous current that carries chilled water from the North Atlantic into the Atlantic, Indian and Pacific basins. The conveyer belt returns water warmed in the tropics back to the North Atlantic.

Ocean currents also affect global heat exchange by redistributing heat, especially in coastal regions. In fact, the oceans have the greatest impact on the Earth’s climate.

Putting It All Together

While all of these things are taking place – at the same time – none of them exists in a vacuum. They are all interrelated and can have a reciprocating effect on each other.

The climatic changes that are taking place can have profound impacts on the Earth’s ecosystems, human health, plant and animal species. Scientists fear that continued melting of sea ice could weaken the North Atlantic Current, the northward continuation of the Gulf Stream. The Gulf Stream transports 100 times more water than all the Earth’s rivers, and a diversion could result in extremely cold winters in the North Atlantic regions, especially in northern Europe.

There are many scenarios. However, human-induced global warming is one that we should pay close attention to because we can control it. If we can reduce carbon-dioxide emissions, it could have a penetrating effect on the natural climatic occurrences that have been affected by human activity. Scientists project that the amount of carbon dioxide released into the atmosphere in the next 20 years will double or triple. The number of cars in operation around the world will double by the year 2030.

Arctic Ice Deluge?

Antarctica is a continental land mass 98 percent covered by thick ice sheets. It contains 70 percent of Earth's fresh water and 90 perecent of Earth's ice. The average ice thickness is 1.5 miles, reaching three miles deep in some regions. Image: NASA

One concern that most people have with regard to the melting of the Arctic Ice Cap, is the eventual flooding of the land masses. What is commonly misunderstood is that the Arctic Ice Cap is relatively thin, about 10 feet thick on average. And about 90 percent of that is already displacing the water (taking up space that would otherwise be occupied by water). Scientists are discovering that the ice cap is melting faster than anticipated.

The major concern, however, would be the increase of fresh, cold water into the marine environment. This would alter ecosystems and the food chain dependent on the saline waters and would funnel more cold water into the oceanic conveyer belt. As a result, you would see a global climate change due to the introduction of the additional cold water into the southern oceans, and you would see a displacement of plant and animals species dependent on the more saline ecosystems. Some animal species will retreat to the land-based ecosystems.

On the Opposite End of Earth

The Ross Ice Shelf in Antarctica

Antarctica, which covers the geographic South Pole, is itself covered with thick ice sheets. The average ice thickness is about 1.5 miles with some parts reaching as deep as three miles. Antarctica’s ice shelves are also melting, for the same reasons associated with the melting of the Arctic Ice Cap, but not as dramaticly. The melting of the Antarctic ice shelves has resulted in the calving of some of the largest icebergs ever known to exist, such as the series of icebergs that broke off from the Ross Ice Shelf in the spring and summer of 2000. But dramatic melting of Antarctic ice would have enormous impacts on ecosystems, climate and sea levels.

Did you know…?

Hot springs and active volcanoes have recently been discovered far beneath the Arctic Ice Cap in the Arctic Ocean. While the enormous heat and energy from this activity are insignificant contributors to the increase in ocean temperatures, they appear to be an oasis for newly discovered species of plants and animals.
Antarctica is colder than the Arctic even though during the course of the year it receives almost the same amount of sunlight. In fact, Antarctica receives a little more solar energy than the Arctic because the Earth is closest to the sun in December when Antarctica has 24 hours of sunlight.
The Arctic is the northern pathway that water travels between the Atlantic and Pacific oceans.
The greenhouse effect maintains Earth’s average temperature at approximately 60Š F. Without the greenhouse effect, the temperatures on Earth would be so cold that life could not exist.
Sea ice is almost all fresh water, with some salt trapped within it. The salt is actually not part of the ice, but just got caught up in the freezing process.
The Arctic’s ice is, at most, only a few feet thick with water under it. While the water would be anything but warm if you jumped into it, it is at least around 30 F, it is salt water and stays liquid at a lower temperature than fresh water.