Ecoscience: Population, Resources, Environment

By Paul R. Ehrlich; Anne H. Ehrlich et al. | Go to book overview
Save to active project

CHAPTER 2
The Physical World

All the rivers run into the sea; yet the sea is not full.

--Ecclesiastes

The biosphere is that part of Earth where life exists. In vertical dimension it extends from the deepest trenches in the ocean floor, more than 11,000 meters (36,000 feet)1 below sea level, to at least 10,000 meters (m) above sea level, where spores (reproductive cells) of bacteria and fungi can be found floating free in the atmosphere. By far most living things -- most of which depend directly or indirectly on the capture of solar energy by photosynthesis in plants and certain bacteria -- exist in the narrower region extending from the limit of penetration of sunlight in the clearest oceans, less than 200 meters from the surface, to the highest value of the permanent snow line in tropical and subtropical mountain ranges -- about 6000 meters, or 20,000 feet. ( Everest, the highest mountain, rises almost 8900 meters above sea level.) By any definition, the biosphere is as a mere film in thickness compared to the size of the ball of rock on which it sits -- about like the skin of an apple, in fact. The radius of Earth is about 6370 kilometers (km), or 4000 miles (mi).

Of course, conditions within the thin envelope of the biosphere are influenced by physical processes taking place far outside it: by the energy emitted by the sun, 150

____________________
1
Throughout this book physical dimensions are given in metric units, sometimes accompanied by the English equivalent to ease the transition for readers not completely accustomed to the metric system. For more precise conversion factors, see the tables inside the covers of the book.

-11-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited page

Bookmark this page
Ecoscience: Population, Resources, Environment
Table of contents
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen
/ 1052

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?