Lab 3: Land Ice

Introduction

Throughout history, Earth's climate has continuously experienced slow natural swings between being virtually ice free and being almost totally covered in ice. Today, we are somewhere in between these two extremes. Snow and ice exist year-round near the poles and seasonally at lower latitudes. Glaciers cover about 10% of Earth's surface and can be found on every continent except Australia. Glacial ages come and go over millions of years. Interglacial periods, like the one we are in now, are typically spaced apart by hundreds of thousands of years. However, since the industrial revolution, increased carbon dioxide (CO₂) levels in the atmosphere, largely due to the burning of fossil fuels, are pushing Earth toward a warmer climate. Like sea ice, land ice plays a significant role in maintaining Earth's energy balance by reflecting solar radiation back out into space. Glaciers and ice sheets also store about 75% of the world's fresh water (NSIDC, 2013), which makes them vital for human survival.

In the first part of this Lab, you will learn about how glaciers form and the different processes that contribute to glacial mass balance by using an online interactive to explore how glaciers provide scientists with evidence of climate change. In Part B, you will learn about how & why glaciers move. In Part C, you will make a model of a glacier out of a putty-like substance called gak and conduct a hands-on experiment to explore glacial movement.

After completing this Lab, you should be able to:

• describe how scientists use glacial mass balance to look for changes in climate;
• describe how glaciers move and shape Earth's surface;
• create a model of glacial movement using gak/flubber; and
• describe how we know what we know about glacier dynamics

Keeping Track of What You Learn

Throughout these labs, you will find three kinds of questions.

• Checking In questions are intended to keep you engaged and focused on key concepts and to allow you to periodically check if the material is making sense. These questions are often accompanied by hints or answers to let you know if you are on the right track.
• Stop and Think questions are intended to help your teacher assess your understanding of the key concepts and skills you should be learning from the lab activities and readings.
• Discuss questions are intended to get you talking with your neighbor. These questions require you to pull some concepts together or apply your knowledge in a new situation.

Your teacher will let you know which answers you should record and turn in.