1: Earth System Science, The Rock Cycle and the Climate System

Name the Main Spheres of the earth system

Biosphere - all life on earth

Atmosphere - Gaseous envelope around earth including water, aerosols etc

Lithosphere - Upper part of earths surface

Cryosphere - All frozen earth components

Hysrosphere - All water on earth in liquid form

(bio)geochemical cycle

A natural in which elements, chemical compounds and other forms of matter are passed from one organism to another and from one part of the biosphere to another.

what is the rock cycle

• rocks change physical and chemical properties when forced out of equilibrium

• changes in T and P, driven by tectonics

• aided by hydrological cucle, gravity and life

• driven by earths internal heat

what is the hydrological cycle driven by

suns energy that circulates water through evaporation, condensation, and precipitation.

explain why energy and mass transfer from one reservoir to another

• heat energy is unevenly distributed on earth due to rotation, revolves around sun, tilted, non spherical

• mass can be moved into positions where new temp/pressure cause it to become unstable

• mass and energy move through gradients

what is earths tilt

23.5 degrees

chemical model of earths differentiation

subdivision of planet based on chem comp

mechanical model of earths differentiation

• based omn changes in rheological properties of rock (how squishy or hard)

• lithosphere, asthenosphere, outer + inner core

• thinning of lithosphere = divergent

• thickening of lithosphere = convergent

asthenosphere

• part of the upper mantle

• weak + undergoes low rates of ductile deformation as result of thermal gradients

lithosphere

• rigid outer later of the earth

• compromises a number of coherent plates

• brittle

Define and give examples of a positive feedbacks in earths climate system

process internal to the earths climate that acts to enhance the original action

e.g. water-vapour feedback:
temp increase = evaporation increase = more vapour in air (GHG) = air temp increase

Define and give examples of negative feedbacks in earths climate system

Process internal to earths climate that counteracts/moderates the original action

e.g. cloud feedback:
temp increase = evaporation increase = more vapour = more clouds = more reflection of solar radiation = decrease in temp

Describe the evolution of the earths atmosphere

repeated melting of eart led to differentiation of internal structure. volatiles were expelled as volcanic gases (N, CO2, H2O, NH3, H2SO4, SO2)

Water vapour condenses along with soluble gases (SO4) as the planet cools, forming the first oceans. this leaves nitrogen and CO2 dominant.

Nitrogen could have also arrived with comets/released by denitrifying bacteria/oxidation of ammonia

describe the origin of carbon

• stored as organic matter in limestone (CaCO3)

• didnt exist in early precambrian

• if all these storehouses were converted to CO2, levels would be 100-1000s x present level (0.04%)

describe the origin of oxygen

• photosynthesis from plants and cyanobacteria

• other planets lack oxygen and so did the early earth

• increase in conc occured ~2.5Ga by around 1-2%

why has the atmosphere remained relatively stable

• sustained life requires a consistent temp

• higher CO2 in proterozoic led to greenhouse effect then strong cooling as levels decreased

• brightness of sun has increased 25-30% during lifetime of earth

Explain and offer hypotheses for the Faint Young Sun Paradox

1. Feedback between solar radiation and removal of CO2
   - CO2 pressure as large as 10 atmospheres?
   if sun is stronger, oceans warm = increase evaporation = rainfall increase = more weathering = removal of CO2 from atmosphere

2. methane as much as 100 ppm (currently ~1.7ppm) could have offset the faint sun

3. Lower albedo (continental area)

4. Different models for evolution of the sun

stable continental crust

Siberian Craton

currently undergoing continental rifting

East Africa

ocean crust beginning to form

Red sea

mature ocean (still opening)

South Atlantic

mature ocean (beginning to close)

South Pacific

ocean nearly closed

Mediterranean

continental-continental collision

Himalaya