L01_04_Sept_2013_Intro

Temperature record for the last 150 years based on

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Unformatted text preview: hat combines all necessary approaches (physics, chemistry, biology, etc.) to examine and understand how our planet func0ons as an integrated unit. The study of global environmental change is one aspect of Earth System Science Can humans alter the workings of this large, complex, and long- lived chemical- physical system? Es0mates of human popula0on at the dawn of the Agricultural Revolu0on (~10,000 yrs ago) range from about 250,000 to 5 million. World Popula0on 10,000 years ago: When my parents were born (mid 40’s) When I was born (mid 70’s): When you were born (early 90’s): Today: 0.005 billion 2.5 billion 4.1 billion 5.3 billion 7.1 billion current popula0on from US Census Bureau What was the popula0on density at the dawn of the Agricultural Revolu0on (~10,000 yrs ago)? • assume 5 million people • radius of Earth is 6378 km • area of sphere is defined by: 4 πR 2 • assume land area is 20% of total € • pop density = 5, 000, 000 = 0.048 people per sq. kilometer 2 0.2 × [ 4 × π × 6378 ] This i€ equivalent to 20 square kilometers per person! s What is today’s average global popula0on density? • assume 7 billion pe...
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This document was uploaded on 03/26/2014 for the course GEC AS.270.103 at Johns Hopkins.

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