Visualizing Environmental Science

466

However, it is much easier to interpret these num-
bers when they are arranged into a graph like this
(Figure A.1):

Introduction

LEARNING OBJECTIVES

1. Define graph.


2. Explain why graphs are so important in science.

graph is a picture that expresses the re-
lationship between two or more ideas or
quantities. Graphs make this relationship
easier to see and analyze because our
brains are much better at interpreting pictures than
words or rows and columns of numbers. For example,
suppose we wanted to investigate how the eruption of
the 1991 Philippine volcano Mount Pinatubo affected
average global air temperatures. We could collect a se-
ries of temperature measurements before and after this
eruption and put this information in a table like this:

Graphing Appendix

Ye a r

14.0

14.1

14.2

14.3

14.4

14.5

14.6

14.7

1987 1989 1991 1993 1995 1997

Mount Pinatubo

erupts, June 1991

Global average temperature (°C)

Data from NASA Global Land-Ocean Temperature Index.

Figure A.1

Global Average Temperature, 1987 to 1998. Climate scientists

observed that the years following Mount Pinatubo’s eruption were

cooler than previous and subsequent years. This brief cooling period

temporarily interrupted a longer-term warming trend (Chapter 9).

Year Global average temperature (°C)

1987 14.28

1988 14.34

1989 14.23

1990 14.39

1991 14.37

1992 14.18

1993 14.19

1994 14.28

1995 14.42

1996 14.32

1997 14.45

1998 14.61

1. What is a graph?


2. Why are graphs so important in science?

A

For instance, we can tell just by glancing at this graph

that there was a substantial drop in the average global tem-

perature immediately following this eruption, and that it

took four years for this temperature to reach its pre-eruption

level. Consequently, this and most other science textbooks

are filled with graphs to help you comprehend the ideas

and concepts they present. In order to understand this ma-

terial and think like a scientist, you therefore must become

proficient at reading and interpreting these graphs.

This appendix will help you accomplish these goals

by providing a general overview of the nuts and bolts of

graphing, discussing the different kinds of graphs used

in this textbook, and explaining how to use these graphs

to answer scientific questions. It will also give you an op-

portunity to test your understanding of this material by

taking a graphing quiz, formulating your own questions

and hypotheses, and creating your own graphs to help

you answer your questions and test your hypotheses.