geographical debates paper Flashcards
(209 cards)
timescale available for marine sediments
300,000 to 66 million years ago
marine sediments: different oxygen isotopes meaning
low O18 (high O16)= colder
high O18= warmer
timescale available for ice cores
100s to 1000s of millions of years
Antarctica ones go back 800,000 years
timescale available for fossils
millions of years
timescale available for dendrochronology
100s to 1000s of years
(tree’s lifespan)
timescale available for lake sediments
intervals of decades to centuries
millions of years
bug size change seen recently (use to make inferences from lake sediments)
shrink as climate warms
have decreased 20% in last 45 years
when did continents break up from supercontinent Pangea
250 million years ago
when did S America and N America join at Isthmus of Panama
5 million years ago
mount pinatubo eruption stats
1991
20 million tonnes SO2 into atmosphere
earths climate cooled 1.3C over 3 years
mount laki eruption facts
1783
sig effects on weather patterns for 2-4 years eg harsh winters, rainy summers so Europe crops didn’t ripen, Asian monsoon cycle disrupted so food poverty and famine
eccentricity timescale
100,000 year cycle
eccentricity solar radiation differences
30% difference between perihelion and aphelion
obliquity timescale
41,000 year cycle
obliquity angle variation and what is it now
varies between 22 degrees and 24.5 degrees
now 23.4
at 22, summers cooler and winters warmer so increased snow and ice cover
precession timescale
22,000 year cycle
sunspots and faculae time changes
abundance varies in an 11 year cycle
how much does solar irradiance change between min and max due to sunspots and faculae
0.1%
temp of earth if greenhouse effect didn’t exist
-17C instead of 15C
100 million years ago:
global temp
co2 levels
global sea level
6-8C higher than today
coincided with CO2 levels 5x higher than today
s.l. 170m higher than today
what happened 55 million years ago and 35 million years ago
spike in global temps: peaked at 23`c
then rapid transition to colder conditions (with glaciation of Antarctica) which have continued into present day
what time period does quaternary period span
last 2.6 million years
length of a glacial and an interglacial
glacial 100,000 years
interglacial 10-15000 years
most recent glacial name and stats§
Devonian
reached max 20,000 years ago with 1/3 of continental surface covered by snow and ice