welcome to planet earth. sustainability waterin this course we will focus on one environmental...
TRANSCRIPT
Welcome to Planet Earth
SustainabilitySustainability
• In this course we will focus on one environmental resource important to human populations: WATERWATER
• When populations grow too large, they can exploit all resources in a region and are then forced to emigrate
• Can you picture a world in which there is no room or resources for human life?
Population Growth
• There are approximately 5.8 billion people in the world
• The global birth rate is about 27 births per 1000 people per year
• How many babies were born in the last 3 minutes?
• What additional information would you need to know to calculate the increase in world population over the past 3 minutes?
Projected population growthProjected population growth
Figure 1.12 on page 12
Why are there regional differences in population growth?
Where do most people live? Why?
Population density in the Mid- Atlantic Bight
Earth is always changingEarth is always changing
• Some changes happen on time scales we can observe: the tides rise and fall, the seasons change
• Other changes occur over long time periods and we must infer their presence: mountains are built and eroded, plants die and become fossil fuel
• Most resources on Earth are created much more slowly than we consume them
Geochemical CyclesGeochemical Cycles
• What is a cycle?
• Reservoirs in the water cycle
• Fluxes in the water cycle
• Box models
How do you know a How do you know a cycle when you see cycle when you see
one?one?
What are some What are some everyday examples of everyday examples of
cycles?cycles?
Dictionary definition of cycle:Dictionary definition of cycle:
Any period of time or complete process of growth or action that repeats itself in the same order
The basics of a geochemical cycleThe basics of a geochemical cycle
• Reservoirs - a place where the matter accumulates
• Fluxes – transfer of matter from one reservoir to another
• Residence time – the amount of time an average “piece” of matter (molecule, atom) resides in the reservoir.
Residence time is calculated:Residence time is calculated:
Amount of matter in reservoir
Removal rate (or supply rate)
Let’s create our own example!
Focusing on the hydrologic cycle
Major reservoirsMajor reservoirs
• Oceans 97.5%
• Glaciers 1.81%
• Surface water (lakes, streams) 0.016%
• Soil moisture 0.005%
• Atmosphere 0.001%* Nearly all of the water on earth is in the ocean and glaciers
Major fluxesMajor fluxes
• Condensation
• Precipitation
• Infiltration
• Run-off
• Evapotranspiration
We will define each of these today and then spend the next few weeks talking about each in detail.