Climate's Distant Past

Question 1

Trends + Rythyms

Answer 1

global temperature change over a set period of time, repeating cycles of climate

Question 2

Hot house Earth

Answer 2

no persistent glaciers prent
last time 50 MYA

Question 3

Climate forcings, feedbacks, tipping point

Answer 3

factors shown to influence global, regional climate (most are positive)

processes which can amplify or dampen a climate forcing

the state crosses an irreversible threshold of climate forcings
though reversible on a geological time scale

Question 4

Change in sun’s luminosity

Answer 4

caused changes in types of gasses found in the atmosphere
when life first evolved, higher levels of CO2 helped planet stay warm eve with lower solar radiation budget

Question 5

early atmosphere

Answer 5

lack of oxygen
high methane and methanogens, high CO2

photosynthesizers produced oxygen, killed off methanogens who can’t live with oxygen, converted to CO2

Question 6

Ice-albedo feedback

Answer 6

positive feedback between ice formation and increasing albedo lowering temperatures

bc oxygen replaced CO2 in atmosphere, lowered temperature

snowball earth
- ended bc of volcanism

Question 7

Continental drift 3 effects

Answer 7

drifting continents influence temperature
disrupt ocean currents – change direction of heat transfer
when most concentrated at equator, more reflection instead of transferring to areas of deficit
precipitation causes weathering, more in rainy areas but also plates produce new rocks

all led to cooling over the past 50 MY

Question 8

Eccentricity

Answer 8

changing distance between the sun and the Earth, as the Earth orbits the sun
influence solar radiation, length of seasons

Question 9

obliquity

Answer 9

tilt angle, that varies ever 40 thousand years

greater tilt, greater extreme between seasons

Question 10

precession

Answer 10

tilt direction every 23000 years
why seasonal extremes are milder in NH and extreme in SH currently

Question 11

Milanković Cycles

Answer 11

all changes: size of earth’s path, tilt angle and tilt direction

period of high insolation found in interglacial periods
feedback needed to amplify small changes in temperature into climate change (more concentration of methane and CO2)

Question 12

list climate forcings (5)

Answer 12

changes in insolation
changes in composition of atmospheric gas
location of landmasses
exposure of new rock to weathering
variations in earth’s movement