Earth 002

Tuesday, February 9th, 1999
Announcements: The test scheduled for Thursday has been moved to next Tuesday!!! Yeah!!! The second homework assignment was collected today.

Lecture notes:

BIOSPHERE

• Our biosphere is a distinguishing characteristic of our planet...it is very unique
• The biosphere is passive to it's environment: everytime the environment or an element within it changes, the biosphere either moves, adapts, or dies
• The biosphere itself can change the climate

ORGANISMS THAT MAKE UP THE BIOSPHERE

• Autotroph-means self-feeding...uses chemical/solar energy to create organic matter ( CO2 + H2O--> CH2O + O2
• Heterotroph
• Decomposers-bacteria/fungi that take organic matter and break it down

FOOD CHAIN & ENERGY

• Energy is balanced through respiratory processes

• The food chain starts out with 100 units of energy and it is utilized by the autotrophs. As you go further down the food chain, only 10% of each of the previous units are available for use

NUTRIENTS

• The biosphere recycles nutrients
• These nutrients originally come from the weathering of rocks--process is slow, biosphere is linked to the rock cycle
• The biosphere is incredibly efficient-->99.9% of the nutrients in it are recycled

LIMITS TO GROWTH

• The idea of nutrients in the biosphere leads one to think there may be a limit to growth
• Unlimited Resources -->exponential growth

• However, there is a limit to growth, in which population approaches the limit then becomes is equilibrium with the availibility of resources

• There are many different outcomes when dealing with limit to growth, which sometimes result in extinction or eventual equilibrium
• The limit to growth cannot be exceeded unless you are more effecient or the world provides more nutrients

FEEDBACK

• The limit to growth which depends on recycling of phosphorus done by bacteria & fungus

OCEAN CIRCULATION AND NUTRIENTS

• Nutrients aren't distributed evenly across the world

• Surface waters would be rapidly depleted of nutrients...there must be a way to get nutrients back to the surface
• Waters coming up from below--the result of upwelling--returns those lost nutrients back to the surface
• Ocean Circulation defines the amount of nutrient return
• WIND CONVERGENCE-->NUTRIENT RETURN-->WHERE LIFE IS ON SEA

NUTRIENT FUNHOUSE

• In the nutrient funhouse, monsters throw you down the hole, you land on a lower conveyor belt, if you're lucky you get to go back to the surfac eon an escalator. Once you get back to the surface, monsters throw you back down, and the cycle is repeated

CLIMATE CASES

• In the desert, the albedo is .25 (meaning 75% of the solar energy is absorbed)
• In the rainforest, the albedo is .07 (meaning 93% of the solar energy is absorbed)
• EVAPOTRANSPIRATION
• Stomato-pores on leaves-control the exchange of gases and oisture between the planet and the atmosphere
• plants exert force on how energy balance will be completed

ALBEDO-PLANT-CLIMATE FEEDBACK

• Global Warming-->Warmer Earth-->Snow/Ice Retreat-->Continued Warmth over time-->Forward moving trees-->Faster warming in the Spring-->More energy absorbed-->System gets warmer-->Further forward moving trees-->Destroy winter-->Further forward moving trees