CHAPTER 3: OUR CHANGING HYDROSPHERE: ICE TO OCEANS

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 All the water on Earth

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Water on Earth is stored in the ocean, lakes, glaciers, rivers, streams, groundwater, or water vapor. All of this water makes up the hydrosphere (hydro means "water" in Latin) and is part of the Earth’s water cycle. Water is continuously moving between the Earth's surface and the atmosphere through evaporation, and then back again through precipitation. Imagine a lake on a warm summer afternoon. As the sun heats up the water, some of it evaporates and goes into the air as water vapor. As the air cools and becomes saturated with moisture, the water changes back into a liquid through condensation to form clouds. When the clouds get too heavy to hold any more, the water returns to the surface again as precipitation, coming down as rain or snow or sleet or hail. Water is continuously moving through these physical states, from solid (ice) to liquid (rain) to gas (water vapor), all powered by energy from the Sun. 

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Most of the water on Earth is in the ocean – in fact, nearly 97%. The remaining 3% is freshwater and is stored in ice sheets, ice caps and glaciers, groundwater, and surface water such as lakes and rivers. The majority of this freshwater is frozen and stored in the Antarctic and Greenland ice sheets (we'll learn more about these polar regions soon). As you learned in chapter 1, glaciers around the world are changing rapidly. In general, freezing and melting are a natural part of the water cycle, but for glaciers, more ice is melting each summer than falls as snow during the winter, and they are shrinking in size as a result. Glaciers also provide water resources, like drinking water, for downstream communities, but as the size of these glaciers changes, so too does this important resource. This is just one of many big changes occurring in the water cycle and throughout the hydrosphere that we'll learn about in this chapter.

Climate change is affecting many aspects of the hydrosphere, including retreating glaciers, shrinking sea ice, a warming ocean, and subsequently, sea level rise. Big changes in the hydrosphere mean big changes for everyone on our planet.

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 The polar regions

When you hear someone mention the polar regions, they are referring to Antarctic and Arctic regions. Antarctica is a continent at the South Pole, surrounded by ocean. The Arctic on the other hand isn’t a single continent, but rather a vast ocean that is surrounded by the land of many countries in the northernmost region of the Earth. The Arctic countries include the big island of Greenland (which is a territory of Denmark), the United States, Canada, Russia, Norway, Sweden, Iceland and Finland. The Arctic and Antarctica are remote areas, with limited human development and are known for their harsh and cold climate. However, they are also home to some of the most beautiful and spectacular places on our planet.

While the polar regions have attracted researchers and explorers for centuries, major accomplishments (such as reaching the poles) only occurred in the early 20th century. Scientists are still learning a great deal about these unique environments today, particularly since these regions are some of the most sensitive places on the planet to climate change. It is also clear that the impact of a changing climate on these distant regions will actually have a major impact on the rest of the world.

As we learned above, about 70% of the freshwater on the planet is stored in polar regions. The Antarctic and Greenland ice sheets are the two largest ice bodies on our planet. Antarctica itself is nearly 1.5 times the size of the United States! But warming temperatures in these regions is causing the edge of the ice sheets to melt and flow faster, which directly contributes to sea level rise. Sea ice (thin, floating ice) in the Arctic is also changing rapidly due to climate change, resulting in a smaller and smaller area each summer. Both of these changes affect people and animals living at the poles and in coastal regions around the world, as you will learn about more in the coming chapters. As an example, indigenous people living in the Arctic, like the Inuit, have a close relationship with their changing environment. Many of their traditional practices (such as using dog sleds for travel) and food sources are changing, directly related to climate change. However, these changes are not limited here: coastal communities and small islands are already feeling the impact of a rising sea level.

3_2_image03.jpgThe polar regions also have a unique characteristic that influences the temperature around the planet. As we learned, these regions are largely covered by snow and ice, which have a high reflectance – this means that the surface acts like a mirror in that it reflects the Sun’s energy. In contrast, a dark rock or the ocean absorb the majority of the Sun's energy. Scientists call this albedo – or reflectivity – an important process that we learn about more in the next section. For now, we recognize that the polar region's high albedo helps regulate the temperature around the world, but as glaciers and sea ice retreat, this albedo is changing, causing more energy to be absorbed. The increased energy melts more snow and ice, which in turn results in more energy being absorbed.  This process is called a positive feedback effect — an initial small change yields a greater change once it occurs. Take a look at this figure to get an idea of how a positive feedback loop works with melting sea ice.

SEA ICE CHANGES

Sea ice plays an important role in the hydrological cycle and is also considered a sensitive indicator of climate change. Sea ice area changes dramatically every season, and the amount of winter freezing and summer melting can vary greatly from year to year, a term called inter-annual variability. Scientists closely monitor the extent of sea ice, particularly when it reaches its annual minimum. In the Arctic, the annual minimum typically occurs in September, following the warmer temperatures of the summer and before the winter's freezing temperatures begin.

Satellite imagery has helped scientists monitor the total extent of sea ice since 1979. Arctic sea ice has been steadily decreasing over this time. In September of 2012, there was a record minimum of sea-ice extent (3.41 million square kilometers or 1.32 million square miles). Each decade, or every ten years, about 11.5% of the ice vanishes. The melt season has also lengthened by five days per decade. With the decrease in sea ice, several changes occur including less albedo, and therefore warmer surface temperatures that influence the global climate.

The retreat of sea ice in the Arctic Ocean has opened new shipping lanes and allowed for new mineral and energy exploration. The Arctic is becoming a very important, and controversial, region as northern countries negotiate for control and access to these resources.

In contrast to the Arctic, sea ice extent is slightly increasing in Antarctica due to changes in the winds around the continent. There is less than 1% growth per decade since the satellite record began. This growth is not enough to compensate for the global sea ice loss. And although the sea ice in Antarctica may increase, scientists have also found that there have been 85 fewer days of sea ice per year over the past 30 years. 

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  WHAT'S ALBEDO? THE BLACK T-SHIRT STORY


Have you ever worn a black shirt on a sunny day? The black fabric absorbs more energy and makes you feel much hotter than a white t-shirt would.

The difference between how a black surface absorbs heat and a white surface reflects heat is called the albedo effect. Albedo is a measurement of how reflective a surface is. A black surface absorbs 100% of the Sun’s energy. A pure white surface reflects 100% of the Sun’s energy. Your black t-shirt has low albedo, and a white t-shirt has high albedo.

Glaciers and ice caps are similar to a white t-shirt – they bounce back most of the Sun’s incoming energy because they are light in color and have a high reflectance.

Today, increased industrial activity and wildfires are changing the albedo of glaciers throughout the world. Soot, dust, and other particles are transported around the planet by winds and subsequently deposited on glaciers. This “gunk,” which actually has a scientific name, is called cryoconite. It comes from natural dust on land, and from soot from wildfires, coal-fired power plants, wood stove smoke, and diesel exhaust from all around the world. The cryoconite causes the surface to darken and absorb more of the Sun's energy, causing it to melt faster.

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 Greenland

globe_greenland.pngGreenland has a funny name, since it’s really white! One legendary tale says that a Viking named Erik the Red named it Greenland to trick others to voyage with him and settle in this very cold and icy place. Greenland is the biggest island in the world, but it’s certainly not an ideal place for growing crops or vacationing on its beaches. About 80% of Greenland is covered in ice and snow.

But like many other areas around the globe with ice and snow, Greenland’s glacial ice is melting fast. After Antarctica, Greenland’s ice sheet is the second largest mass of freshwater on Earth. Currently, its rapid melting contributes about 0.5 millimeters of the average 3 millimeters in sea level per year. While this doesn’t seem like a lot, a few millimeters rise all around the globe, every year can add up quickly.  Scientists are also concerned that the rate of melting and sea level rise will continue to rise in the coming years, leading to greater changes.

The ice on Greenland is really thick. In fact, it can be 3 kilometers (1.9 miles) thick, but researchers have found that it is thinning. The shape of the land beneath the ice sheet influences the way that ice melts on the surface, and which areas of the ice cap grow or shrink throughout the year. In addition, the meltwater from the top and seawater from below can seep into the weak areas of ice, causing it to melt more quickly into the sea.

One study used special radar instruments to see what is under the ice, and scientists discovered a massive canyon that is 740 kilometers (460 miles) long! This canyon is longer than the Grand Canyon in Arizona, but its been covered by ice for about 4 million years. There is still a lot we are discovering about Greenland.

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  WHAT'S A TIPPING POINT?


A tipping point is when a steady change in something suddenly leads to dramatic effects. Think about filling a large tub with ice cubes that get warmer over time. Let’s say the starting temperature was -10°C (14° F) at eight o’clock in the morning, and each hour the temperature rises 2 degrees. Nothing would change in the tub of ice until five o’clock, when the temperature reaches 0°C (32°F) and all the ice suddenly begins to melt. This is the tipping point of ice. Climate scientists are concerned that the temperature of the Earth may reach a similar tipping point that would result in major changes and accelerate positive feedback loops that would bring even greater change. 

 

 

An example is if Greenland’s ice reached a tipping point where the entire ice sheet began to melt and could not be stopped. The melting would accelerate and lead to even greater climate changes. If all of the ice on Greenland melted, sea level would rise more than 7 meters (23 feet). This would have major impacts on all the coastal cities around the world. Many islands would be completely submerged, along with big cities like New York and Miami.

WHAT'S GLACIER MASS BALANCE?

Take a look at the graph here to see how much Greenland has melted over the past decade. As you can see, Greenland’s total ice volume is declining. Scientists carefully measure changes in the ice as the mass balance variation – which means the gain and loss of ice from a glacier system over time. Naturally, glaciers will grow when they receive snow during the winter, and shrink when they lose ice through melting during the warmer summer months. However, we must monitor how much a glacier’s mass balance changes over several years' time to determine if the glacier is indeed retreating. If the glacier is gaining (accumulation) more mass than it loses (ablation), then it is in positive mass balance. On the other hand, if the glacier is receding, then it is losing more mass than it is gaining each year. Glacier mass balance (b) is the product of accumulation (c) plus ablation (a). Mass balance (b) = c + a.

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 Antarctica

4_2_globe_antarctica.pngAntarctica – a vast, cold, wind-swept and ice covered continent at the bottom of the Earth. It's nicknamed the ‘big white’ because of its enormous size and overwhelming amount of snow and ice.  Another nickname is the ‘crystal desert’, because despite all the snow and ice present, very little snow is added on every year. In fact, it's a desert, with only 200 millimeters (8 inches) of average precipitation per year. There are no permanent inhabitants in Antarctica, but numerous research stations across the continent support many scientists conducting studies.

3_4_image_map.jpgAll the snow and ice on Antarctica covers nearly 98% of the continent. The ice averages about 2.4 kilometers (1.5 miles) thick, but is nearly 4.8 kilometers (3 miles) thick in some places. With all this ice, it is no surprise that Antarctica holds the majority of the world’s freshwater.

Geographically, Antarctica is divided into east and west by a mountain range called the Transantarctic Mountains. Eastern Antarctica is much larger, and on average, is higher in elevation and colder than West Antarctica. Antarctica has the highest average elevation of all the continents. Many mountains are more than 3,000 meters (nearly 10,000 feet) above sea level, with the highest mountain peak, called Vinson Massif, reaching 4,897 meters (16,066 feet).

3_4_image_map02.jpgThe animal life on and around Antarctica consists of many different sea birds, seals, penguins, whales and colossal squids. As you'll see in the next chapter, there are many different kinds of penguins that live on Antarctica. But life on Antarctica isn’t limited to the animals that we often see pictures of. There are also hundreds of different kinds of mosses, lichens, fungi, algae including phytoplankton, and small crustaceans (krill) that all are an integral part of the Antarctic food chain. All of these species are very specialized and adapted to the freezing temperatures. Changes in temperature from climate change, both in the atmosphere and in the ocean, impact their ability to survive, and therefore affect the survival of Antarctic and oceanic ecosystems.

Antarctica is sensitive to changes in climate and thus recent warming has led to dramatic impacts. The average surface temperature of the continent has increased .22 degrees Fahrenheit (.12 degrees C) per decade since 1957 for a total average temperature rise of 1 degree F (0.5 degrees C).

Many scientists from all over the world come to Antarctica to study the complex changes of glacier ice and how it relates to recent climate change. Overall, the land ice on Antarctica is decreasing, but the amount of sea ice is increasing. Land-ice melt is very important to monitor because it directly contributes to sea-level rise; when ice on the land melts, that water runs off into the ocean. Researchers have found an accelerated melting on the fringes of the West Antarctic Ice Sheet that is due to warm ocean water circulating underneath. Studies continue to explore the different rates of accumulation and ablation across Antarctica. Take a look at the graph below to see how the total glacier mass balance on Antarctica is declining. In early 2014, James and the EIS team went to Antarctica and set up time-lapse cameras to monitor how certain glaciers on this continent are changing. All eyes are on Antarctica to see what may come of this special glacier landscape, a site like no other on Earth.

01 ONLY ONE DAY AND ONE NIGHT A YEAR

The South Pole is the southernmost point on the surface of the Earth, located on the continent of Antarctica. At this exact location, the sun rises on March 21 on the spring equinox, and sets on September 21 on the fall equinox. This means that there is sunlight all day and night for six months during the summer, and darkness 24 hours a day during the winter. That makes for one very long ‘day’ and one very long ‘night’ at the South Pole each year. In the summer, the Sun is always very low on the horizon, and never directly overhead. This is why the South Pole is a very cold place, especially in winter when the Sun isn’t seen at all. 

02 GETTING TO THE SOUTH POLE

A little more than 100 years ago, on December 14, 1911, the Norwegian explorer Roald Amundsen was the first person to reach the South Pole. It took Roald 99 days, five men, 4 sleds, and many dogs to travel over 2,900 kilometers (1,800 miles) to reach the South Pole. A month later, a British explorer Robert Falcon Scott also reached the Pole. This was a great achievement, as getting there is far from easy. Even today, driving to the Pole from the coastline can take up to four weeks, traveling twelve hours and about 45 miles a day. A special vehicle is needed and the road is always surveyed for crevasses. Most visitors and scientists traveling to the South Pole today fly there by plane. 

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 Ocean changes

Earth actually has one big ocean – sometimes called the World Ocean – that covers 70% of the surface of the planet. The World Ocean is made up of interconnected ocean basins including the Pacific, Atlantic, Indian, Southern and Arctic. The ocean plays a key role in the water, heat and energy cycles on Earth. The ocean influences the global temperature of Earth and atmospheric processes that impact weather and climate. It absorbs most of the solar radiation reaching Earth and about half of all the carbon dioxide that is added to the atmosphere. The ocean is working hard to keep our planet in balance.

Human activities are leading to major changes in the ocean. The uptake of carbon dioxide has caused the ocean to acidify, and both the melting of glacier ice and warming ocean temperatures are causing sea level to rise. These changes not only affect the plants and animals of the ocean, but also result in consequences for communities all around the world. Many people living in coastal zones are susceptible to increasing natural hazards resulting from climate change, including sea level rise and extreme weather events. We will learn more about the impacts on people in chapter 5, but for now we can see that humans and the ocean are definitely interconnected.

Sea level rise is caused by two major factors: melting glaciers and ocean thermal expansion. First, let’s consider glacier contribution to sea level rise. As we examined earlier, glaciers on land hold about 70% of the fresh water on Earth, but as they melt, the addition of water to the oceans causes sea level rise. The majority of glacier contribution to sea level rise comes from small glaciers and ice caps on land, followed by Greenland, and then Antarctica.

3_5_image04.jpgSecond, water expands when it absorbs heat. Thermal expansion of the ocean is occurring because the oceans are getting warmer, and this in turn causes sea level rise. Take a look at these images to see how sea level rise of one to six meters would impact the southeastern United States.

Ocean warming not only contributes to sea level rise, but also changes the chemistry of the ocean, which has major implications for marine life. When the ocean absorbs extra carbon dioxide from human activities, it leads to ocean acidification. Since the Industrial Revolution, ocean acidification has risen by about 30%. A lowered pH and higher acidity of the ocean directly affects marine organisms, which use calcium carbonate minerals to build their skeletons and shells. Ocean acidification is causing marine animals to make weaker shells than before the water turned acidic. Coral reefs are bleaching because of the change in water chemistry. Keeping our World Ocean healthy is important because it provides many needs for society, from recreation to food to jobs. Above all, the ocean has allowed life to develop on Earth and provides the essential elements to sustain biodiversity and humans, including water, oxygen and nutrients.

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 Conclusion

3_6_image.jpgThe water on our Earth is what makes our planet unique and habitable. Certainly we couldn’t live without water, and access to clean and fresh water is a natural right for everyone. Most of the planet’s water is stored in the ocean, and most of the freshwater is stored in glaciers and ice caps. Current warming is affecting both the ocean and glaciers everywhere, which is having major impacts on the energy, heat, and water cycle of our planet. Major changes are being witnessed in the polar regions of Greenland and Antarctica. Our oceans are changing too, with warming temperatures and ocean acidification. These big changes in our climate are leading to new challenges for society and the environment. In the next chapter, we will take a look at how plants and animals are impacted by these changes. 

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 A Wild Afternoon in Greenland

In May of 2008, two EIS team members, Adam LeWinter and Jeff Orlowski, were camped at the edge of the Ilulissat Glacier in Greenland. They were the only two people within a 100-mile radius. The only way in and out of their campsite was by helicopter. Very isolated and fighting the frigid temperatures, Adam and Jeff were on glacier watch around the clock, with their cameras ready to film and photograph any movement in the glacier. They had nine cameras set up – five time-lapse cameras and four video cameras. They were prepared to wait for several weeks – that is, if their tent didn’t blow away first. Each took turns sleeping so that somebody was always on watch.

On day 17 of their expedition, which was May 28, at 6:08 p.m., a huge calving event began. Calving is when large portions of ice fall off the edge of a glacier. When the glacier calving began, they heard a very low rumble, almost like a deep growl, that seemed to shake the air. Adam and Jeff were astonished to see the glacier begin to massively crumble before their eyes. They watched 3,000-foot tall towers of ice break off and roll off into the ocean. With cameras rolling, 75 minutes later, when the calving stopped at 7:23 p.m., the Extreme Ice Survey had just recorded the largest calving event ever caught on film.

Below is the video, with the footage sped up so you can view the entire calving event in a very short period. The icebergs you see are enormous! When EIS measured the ice both above and below water, the team discovered that some icebergs were as much as two and a half times the height of the Empire State Building in New York City. Above the water, glacier pieces shoot up to 600 feet into the sky, and some of the icebergs that are rolling up from under the water are 250 stories tall.

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