The Environmental Literacy Framework (ELF) was made possible through financial support provided by Energy Geosphere As part of NOAA Environmental Literacy Grant #NA09SEC490009 to the University of Nebraska Lincoln's, ANDRILL Science Management Office. Hydrosphere Environmental Literacy Framework With A Focus On Climate Change Biosphere Atmosphere This material is based on work supported by an Environmental Literacy Grant from the National Oceanic and Atmospheric Administration's Office of Education (NA09SEC4690009). Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the authors and do not necessarily reflect the views of the NOAA.
Environmental Literacy Framework Build a Model Focus Questions: If floating ice (ice shelves and sea ice) melts, will sea levels around the world rise? If land-based ice (glaciers and ice sheets) melts, will sea levels rise? Preview Imagine what would happen if more snow fell every winter than could melt away in the summer. During the first storm of each winter, fresh new snow would land on top of the previous year s dirty old snow. More new snow would be added to the top of the pile with each storm. During summers, the surface would get darker from dust and experience some melting. After a century or more of adding such layers, the pile of snow would grow quite thick. The darker summer surfaces would form layers on the top of each winter s snow. Layers of snow near the bottom of the pile would eventually get compressed by the weight above them. Individual snowflakes would be squeezed together so tightly that they d merge together into solid ice. When the snow-turned-to-ice begins to flow downhill under the force of gravity, a glacier has formed. At the bottom of the glacier Even when a pile of snow gets larger every year, some of the snow melts during the warmer months. Liquid water trickles down to the land below the snow. When this water refreezes, it expands, and rocks from the land s surface get frozen into the bottom of the glacier. As the glacier moves downhill, it carries these rocks with it, and the rocks and ice grind over the land. Time 45 minutes Materials Disposable paper or styrofoam bowls Mixture of gravel, sand, and silt-sized sediments (2-3 cups) Pepper Clear plastic wrap Corrugated cardboard (3-4 pieces, each 18 x 10 ) Clear packaging tape Scissors Snow, shaved ice, or crushed ice. Ice chest or cooler for storing ice Freezer Large sheets of poster board or construction paper Towels (for cleanup) Vocabulary (Terms) Ice sheet Ice shelf 189 -filled valleys in Antarctica. Photo by Michael Rynbrandt, National Science Foundation
Environmental Literacy Framework Activity 3D-Build a Model Prepare The Preview section tells how real glaciers form. While you re building your model glacier, refer to that description and discuss which part of a real glacier you are modeling in each step. 1. Pour a spoonful of mixed sediments into the bowl. Add three spoonfuls of snow, shaved ice, or crushed ice plus a tablespoon of water. Stir the mixture and flatten it into the bottom of the bowl. 2. Add 2-3 spoons of ice on top of your first layer and flatten it again. Press the surface for a while so the warmth of your hand causes a little melting. Add a very light dusting of pepper. 3. Repeat step 2, adding thin layers of ice until your glacier fills the bowl. An Optional Extension: Make some mountains and grow an ice sheet If snow continues to accumulate, a glacier can get so thick that it fills its entire valley. Individual glaciers can grow so large that they overflow their valleys and cover the mountains between them. When glaciers merge with other glaciers to form a blanket of ice over a huge area of land, an ice sheet has formed. Height = 30 to 45 cm Top = 20 cm Base = 25 cm 1. Use the dimensions at left to cut three trapezoids of cardboard. Fold along the center line and use tape across the open side to hold the cardboard in to a triangular prism. These are your model mountains. 2. Wrap the individual mountains in plastic wrap, then line them up parallel to one another. Use tape across the bottom to connect them, forming a model landscape of three mountain ranges with two long valleys. Tape 3. Place two or three model glaciers in a line in each of your valleys. 4. Use your imagination to consider how the valley glaciers could continue growing to form an ice sheet. 5. When you are ready to demonstrate how an ice sheet forms, you ll pack crushed ice around the model glaciers and add more layers of ice over your model landscape. You ll keep adding snow until the valleys fill up and cover the mountains. 6. Cover all the model glaciers with plastic wrap and store them in a freezer so they are ready to use at your Flexhibit. 190
Practice Got the Big Idea? In places where more snow falls than can melt each year, layers of snow build up and glaciers form. s show annual layers that are similar to tree rings. If glaciers keep growing, they can merge together to form an ice sheet. Plan your presentation Consider how you can set up this station so that your visitors will have a chance to interact with ice. You can invite visitors to add a layer of snow or ice on the top of model glaciers, or they can add ice to show the formation of an ice sheet in your model landscape. Explain that the model shows how Antarctica became the icy continent it is today, one snowstorm at a time. Ponder Tree rings offer one way of studying past climates. From spring through fall, a ring of light-colored wood grows around the outside of a tree trunk, just under the bark. When winter comes, a layer of darker wood grows. During years when trees have plenty of water for growing, they produce more of the light wood than they do during dry years. Consider how annual layers of snow are similar to and different from tree rings. What do you think you could find out by studying snow layers and tree rings? Photo Henri D. Grissino-Mayer, The University of Tennessee 191
Special preparations for this station At your Flexhibit, this station needs to be set up in a way that you can keep the water produced by melting ice from getting everywhere. You might place the downhill edge of your model landscape on a tray, or place the whole model inside a shallow plastic bin. Plan to have several sponges or towels on hand to soak up melting ice. This station also requires a considerable supply of crushed ice. Athletic departments at high schools or school cafeterias may be places where you can fill a large cooler full of ice for your Flexhibit event. Consider how long your Flexhibit will last and how fast the ice will melt to figure out how much ice you ll need for the whole event. Present As visitors add ice to your models, ask them to imagine that it is winter and lots of snow is falling. Afterwards, encourage them to make summer happen by warming the ice surface with their hands. Be ready to explain that solid glaciers move downhill without melting, though your model does have solid ice turning to liquid. Share the fact that the same process that builds glaciers (accumulating snow) on a local scale results in formation of an ice sheet on a larger scale. 192
Background Information for the Teacher Ice Shelves are floating extensions of land glaciers that move toward the coasts under the weight of accumulating snow and ice in the interior of the continent. Approximately 44% percent of the coast of Antarctica has an ice shelf. As the ice shelf advances over the ocean, pieces break off forming icebergs. Advance and retreat of ice shelves is a natural cycle, however in 2002 the Larsen B Ice Shelf in the Antarctic Peninsula indicated that the glacier flow was accelerating. For more on the story go to this website. http://earthobservatory.nasa.gov/features/worldofchange/larsenb.php The two largest ice shelves in Antarctica are the Ross Ice Shelf (487,000 sq mi/148,437.6 m, 2600 ft/792.48 m thick) and the Ronne Ice Shelf (430,000 sq miles/131,064 m, 3000 ft/914.4 m thick). The Ross Ice Shelf moves toward the ocean at a rate of approximately 3000 ft/914.4 m per year. When glaciers move onto the oceans they add volume and increase sea level. However, once floating on the water, melting or break up of the shelf does not increase sea level rise. Sea ice forms when ocean water freezes forming a thick solid sheet of ice that extends away from the shore. During the Arctic winter, 9.32 million sq m/15 million sq km cover the Arctic Ocean region which shrinks to 4.34 million sq m/7 million sq km in summer. For Antarctica, the sea ice extent ranges from 11.8 million sq m/19 million sq km in the winter to 2.17 sq m/3.5 million sq km in the summer. These large ice shelves work to control the heat exchange between the polar oceans and the atmosphere, limit the access of the water underneath to receive sunlight and increases the albedo of the oceans. The sea ice reflects solar radiation which helps keep the planet cool. Many scientists are concerned about shrinking ice because of its effect on climate as water absorbs solar radiation and adds to the Earth s heat budget. Pack ice are large rafts ( floes) of ice which extend away from the shore. About 90% of the frozen ocean is pack ice. The other 10% is called fast ice and is attached to the land. Both these sea ice formations support a wide array of life from diatoms to seal and whales. Fluctuations in floating ice (pack ice, fast ice, ice shelves and the North Pole ice cap) does not affect sea level. For more information on sea ice formation go to the website: http://earthobservatory.nasa.gov/features/worldofchange/sea_ice_south.php s are large amounts of land ice that build up with the accumulation of snow falling over thousands to millions of years. Under the weight of the ice and the influence of gravity, glaciers move toward the coast. As the glaciers move over the surface of the land, they carve landscapes, erode and break up rocks, and carry away the resulting sediments. As the Earth s climate changes over geologic time, glaciers advance and retreat. In the last few decades most of the world s glaciers are retreating. During cooler times in the Earth s history, glaciers covered large parts of continents and the sea level was lower than it is now. As the glaciers retreated and the ice melted, sea levels rose. When glaciers melt, water is returned to the oceans and sea levels rise. 193 For more information on glaciers, go to the website: http://climate.noaa.gov/warmingworld/glaciers.html Arrigo, K. 1998. Antarctic Sea Ice Biological Processes, Interantionc, ad variability, Antarctic Research Series, Vol 73, p 23-43
Build a Model In this activity students build a model of a glacier to demonstrate how glaciers and ice sheets form, fill in valleys and change landscapes. NSES gr 5-8 CLEP ELF EARTH Oceans have a major effect on climate, because water in the oceans holds a large amount of heat. 2B Changes in ocean circulation caused by tectonic movements or large influxes of fresh water from melting polar ice can lead to significant and even abrupt changes in climate, both locally and on global scales. The earth processes we see today, including erosion, movement of lithospheric plates, and changes in atmospheric composition, are similar to those that occurred in the past. 4 A. Climate is determined by the longterm pattern of temperature and precipitation averages and extremes at a location. Climate descriptions can refer to areas that are local, regional, or global in extent. Climate can be described for different time intervals, such as decades, years, seasons, months, or specific dates of the year. 4 D. Scientific observations indicate that global climate has changed in the past, is changing now, and will change in the future. The magnitude and direction of this change is not the same at all locations on Earth. Glossary Unit Activity Vocabulary Word Hydrosphere Build a Model Definition A large persistent body of ice that accumulates over time Hydrosphere Build a Model Ice sheet A large glacier or system of glaciers covering a significant part of a land mass Hydrosphere Build a Model Ice shelf The part of a glacier or ice sheet which extends over the water 194