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Chapter 23: Global Change in the Earth System

Geotours

Download Geotours.

Getting Started :

If you haven’t done it already, download Google Earth™ and install it on your computer.
If you haven’t done it already, download the Geotours.kmz file and save a copy to your desktop. (The Geotours.kmz file contains the Geotours for all chapters, so you only need to download this once!)
By downloading Geotours.kmz you acknowledge that it was created solely to accompany Steve Marshak's Earth: Portrait of a Planet and Essentials of Geology and is limited to use with only Steve Marshak's Earth: Portrait of a Planet and Essentials of Geology and may not be reproduced, stored in a retrieval system, or transmitted in any form by any means for any other purpose without the written permission of the publisher.
Double-click the Geotours.kmz file and Google Earth™ will open automatically.
In the left-hand sidebar you will see a Places menu, and in the Temporary Places folder you will see an EARTH_3e.kmz file. Double-click the file and you will see a list of Geotours for each chapter.
Then open the Geotour folder you want to explore! If you’d like to read more about the features of Geotours see Using Geotours, or go to our Helpful Resources section.

STOPS ON GEOTOUR 23: Aspects of Global Change

Clear-Cutting the Amazon, Brazil

See also Worksheet Problem 1

Long-Term Deforestation, Brazil

See also Worksheet Problem 2

Edge of Everglades National Park, Florida

See also Worksheet Problem 3

Urbanizing the Desert, Arizona

See also Worksheet Problem 4

Receding Glacier, Switzerland

See also "What a Geologist Sees" Geofeatures: Valley Glacier, 2 Lateral Moraines, Recessional Moraine, U-shaped Valley and Hanging Valley

Melting Permafrost, Siberia
Intense Urbanization, Tokyo, Japan

See also Worksheet Problem 5

Sustainability of Village and Fields, China

See also Worksheet Problem 6

Desertification of the Sahel, Africa

GEOTOUR 23 WORKSHEET

Human activity has become a major agent of change on planet Earth. The consequences of this activity are clearly evident in the character of landscapes on the surface.

Clear-Cutting the Amazon, Brazil
1. Double-click and check the box next to the placemark labeled Problem 1. You’ll fly to a spot ~600 km above the Brazilian rainforest.

(a) What is the total area (sq km) of your field of view? (Hint: Simply measure the length and width of the image and multiply.)

(b) Do a “back-of-the-envelope” estimate of the area that has already undergone deforestation in this field of view. Scientists use such estimates to obtain an order-of-magnitude sense of a quantity. (Hint: To do this, first note that there are two main bands of deforestation. Measure the length and width of each one, multiply to get its area, and sum the two areas. Then, just by looking at the image, determine if about 10%, 25%, 50%, or 75% of the belts have been deforested. If it looks like about a quarter of the belt has been deforested, for example, then multiply your calculated area by 0.25 to get your estimate the area in sq km that has been deforested.)

(c) Using your answers from Problems 1a and 1b, calculate the percentage of the total field of view that has already been deforested.

(d) By comparing a satellite image (such is the one you are looking at) from one year to the image for the same area from the previous year, researchers determine that Brazil loses about 9,600 sq km of rain forest every year. If all this cutting were to take place in your field of view, how long will it take for the entire field of view seen in the placemark for Problem 1 to be deforested?

Your answer gives you a sense of the rate of rain forest destruction.

Long-Term Deforestation, Brazil
2. Double-click and check the box next to Images G23.3–4.

(a) Incline the image and look in various directions. Are the remaining forested areas within valleys or on hilltops?

If the distribution of deforestation were reversed, do you think rates of headward erosion in valley streams would be faster or slower? Explain your answer.

(b) Click on the placemark for Problem 2, and you will fly over the city of Monte Claros. Zoom down to an elevation of 1 km. To get a sense of how urbanization changes the land surface, estimate the percentage of land within the field of view that is covered by grass or trees.

Edge of Everglades National Park, Florida
3. Image G23.5 shows the stark contrast between the natural Everglades (to the west) and developed land (to the east).

(a) Based on the alignment of hammocks of grass (the elongate ridges that are slightly above the wet area), and on the position of the coast relative to this area, what is the direction of regional water flow in the Everglades?

(b) Turn on the Parks and Recreation Areas layer in the Layers panel in Google Earth^TM. The boundary of the Everglades appears as a green line. Note the sharpness of the boundary between developed land and park land in the field of view. This contrast emphasizes that establishment of parks helps preserve land in its original state. Now, fly out to 150 km. You will see a broad area of wetlands north of the Everglades National Park border. If developers or farmers utilize this land, what will happen to the source of water for the Everglades, and therefore to the ecosystem of the Everglades?

Urbanizing the Desert, Arizona
4. Double-click and check the box next to the placemark labeled Problem 4. You will find yourself hovering above a housing development built around a golf course on the NE side of Phoenix, Arizona.

(a) Considering that this area is a desert, what are two possible sources of water to keep the golf course green?

(b) Zoom out to an elevation of 15 km and note the boundary between the developed land and the undeveloped land. Examine the pattern of development in along this boundary. Are new housing developments sprouting in valleys or on ridges?

What natural hazard might these new developments face?

Intense Urbanization, Tokyo, Japan
5. Fly to the region shown in Image G23.10 and you will be over a portion of Tokyo, Japan. Studying this area gives a sense of global change issues that coastal cities face.

(a) How far is the placemark for Image 23.10 from the coast of Tokyo Bay (in km)?

(b) How much sea-level rise, or land subsidence would have to happen for this community to be submerged (in m)?

(c) If the Greenland ice sheet were to melt, sea level would rise about 7 m. What impact would such a change have on Tokyo and comparable coastal cities worldwide?

Sustainability of Village and Fields, China
6. Click on the placemark for Image G23.11 to see an agricultural area in China. The placemark lies at the center of a village. Studying this area can help introduce the issue of sustainability.

(a) How many buildings comprise the village indicated by the placemark? (Hint: To do a “back-of-the-envelope” calculation, zoom down to 300 m. Count the number of buildings in a 0.1 km × 0.1 km square. Then measure the dimensions of the whole village, and multiply to get an estimate of the total number of buildings.)

(b) What is the population of this village? (To do this “back-of-the-envelope” estimate, assume that there are three people living in each building.)

(c) Zoom out to an elevation of 8 km. How many villages lie within your field of view? Assuming that your answer to Problem 6b more or less represents the population within each village, what is the overall population of the field of view?

(Note: The village spacing basically reflects the distance that people could walk to reach fields in the era before modern modes of transportation became available.)

(d) The region appears to be utilized to its fullest extent. Assume that the people in the region currently consume all of the agricultural products grown in the region. How much land, in square meters, does it take to support a single person? (Hint: Calculate the area of the field of view, and subtract out an estimate of the area covered by villages. Then, divide the area by the total population.)

(e) If the population of the region in view were to grow substantially, either villages would get larger or their population density would increase. What other change would have to take place in order for population growth to be sustainable?

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StudySpace: Chemistry 2e.