Owens Lake

Mono Lake, 1981

•Example of a relatively small

system is Mono Lake in California

Page 26-28

-Terminal lake

-Brine shrimp,

alkali fly, algae,

migrating birds

-Answer Check point questions, pg. 28

(pictures from Wikipedia)

System Analysis

Environmental Science

Mr. Schisel

•System Analysis

•making observations of the inputs,

outputs, and changes in a system under

various conditions

• inputs: additions to a system

•outputs: losses from a system

•Steady States

•is when inputs = outputs

•the system does not change over

time

•Feedbacks

•adjustments in input or output rates

caused by changes to a system

•2 kinds of feedbacks:

negative feedback loops

positive feedback loops

•Negative Feedback Loops

•when a system responds to a change by

turning back to its original state

or

• the reduction in the rate at which the

system is changing

http://ecoplexity.org/model_feedback

•Example of a Negative Feedback Loop

• Imagine you are out walking in the country. As you

walk, the sun rises higher

in the sky and the air temperature increases. Your

body senses that your internal temperature is rising

above 370C and you start to sweat, which reduces

your body temperature by evaporating water from

your skin, returning your temperature to normal

http://www.slideshare.net/quercuscymru/overview-of-environmental-systems

•Positive Feedback Loop

•when change in a system is

amplified

•Hypothermia

Decomposition

•The health of many

environmental systems

depends on the proper

operation of feedback loops.

•Passage of Time

Natural systems are also affected by the passage

of time.

http://geology.com/records/sahara-desert-map.shtml

http://enviro-map.com/sahara-desert-map

http://knowledge.allianz.com/climate/impacts/?621/green-sahara-how-climate-change-transformed-the-desert

•EcoTipping Point

• An EcoTipping Point is a lever that reverses

environmental decline, setting in motion restoration

and sustainability.

• View the following video identify the positive

feedback loops and the negative feedback loops in

Rainwater Harvesting (Rajasthan, India).

http://www.youtube.com/watch?v=DG2DtF_mWww&feature=youtu.be

•Feedback Loops &

Tipping Points:

• Feedback loops are the key to how EcoTipping

Points work. EcoTipping Points set in motion a

cascade of effects that reverse the vicious

cycles responsible for environmental decline.

• An example of this can be found on

pages 52-55 in your book. Read your book

and complete the worksheet.