Holocene

Question 1

when is present, when we refer to BP dates

Answer 1

1950

Question 2

how did we find the starting date for the holocene?

Answer 2

a series of independently dated events indicative of rapid climate change between 11k & 11.8k cal yr BP

Question 3

which epoch came before the holocene

Answer 3

pleistocene

Question 4

when is the pleistocene holocene boundary

Answer 4

•11.7 kyr before 2000

Walker et al 2009

Question 5

4 characteristic trends in the holocene

Answer 5

rapid warming, after the younger dryas ended

a few abrupt cool events, such as at 8.2 kyr BP

holocene reaches relatively stable climatic optimum

neoglacial cooling (3ka to present)

Question 6

name the 3 ages within the holocene epoch

Answer 6

greenlandian, northgrippian, meghalayan

Question 7

dates of the meghalayan age

Answer 7

4.25 kyr b2k - now

4250 years before 2000CE

Question 8

what is argued to come after the meghalayan age

Answer 8

anthropocene

ruddiman 2013

Question 9

name external climate forcing factors

Answer 9

milankovitch cycles
solar variability
explosive volcanic eruptions

Question 10

what are the 3 milankovitch cycles

Answer 10

eccentricity, obliquity, and precession

Question 11

how long does an eccentricity milankovitch cycle take

Answer 11

96ka

Question 12

how long does an obliquity milankovitch cycle take?

Answer 12

42ka

Question 13

how long does a precession milankovitch cycle take

Answer 13

21ka

Question 14

what is the eccentricity milankovitch cycle caused by

Answer 14

changes in the shape of the earth’s orbit around the sun

Question 15

what is the obliquity milankovitch cycle caused by

Answer 15

changes in the earth’s axial tilt

Question 16

what is the precession milankovitch cycle caused by

Answer 16

the earths axial tilt wobbling in a gyroscopic spinning motion

Question 17

what are the milankovitch cycles

Answer 17

changes in the Earth’s orbit, either around the Sun, or on its own axis

Question 18

climate impacts of milankovitch cycles

Answer 18

Affects amount of solar radiation reaching differing parts of
the Earth

Question 19

what is mean solar irradiance

Answer 19

output of light energy from the entire disk of the Sun, measured at the Earth

Question 20

length of solar schwabe cycle

Answer 20

11 yrs

Question 21

direct ways to measure solar variability

Answer 21

satellites analyse sunspots and solar activity

Question 22

indirect measures of solar variability

Answer 22

cosmogenic isotopes :
–10Be from ice cores; 14C from tree rings
–bombardment galactic cosmic particles on 16O and 14N
– a process known as “spallation”

(Muscheler et al. 2007)

Question 23

what is a sunspot

Answer 23

an area of weakness within the shielding provided by the sun’s magnetic field, leading to more heat being released to the earth
(hansen et al 2013)

Question 24

how do explosive volcanic eruptions cause explosive volcanic eruptions

Answer 24

they create dust veils, ejecting SO2 into the stratosphere, which gets converted into a sulfate, reflecting solar radiation, they also release ash and other greenhouse gases

Question 25

time scale of climate effect creeated by an explosive volcanic eruption

Answer 25

several years

Question 26

net temperature effect of explosive volcanic eruptions on the stratosphere

Answer 26

net heating

Question 27

net temperature effect of explosive volcanic eruptions on the troposphere

Answer 27

net cooling

Question 28

are volcanic eruptions more impactful on the global climate at low or high latitudes

Answer 28

low latitude eruptions (in the tropics) result in greater stratospheric warming due to the nature of atmospheric circulation

Question 29

name 3 internal forcing factors

Answer 29

thermohaline circulation ocean-atmosphere dynamics greenhouse gases

Question 30

where does most of the heat caused by global warming go

Answer 30

the ocean. 2019 had the hottest ocean temperatures on record

Question 31

cause of weakened north atlantic THC

Answer 31

meltwater entering ocean, altering or stopping THC route

Question 32

global cooling event caused bu north atlantic THC weakening

Answer 32

8.2ka b2k

Question 33

what does ENSO stand for

Answer 33

ENSO: El Niño Southern Oscillation

Question 34

how does ENSO work under normal conditions (not el nino or la nina)

Answer 34

``` S American water heated by sun moves towards new guinea forms warm pool at new guinea this cools and sinks moves along the bottom back to S america upwells w lots of nutrients from the bottom ```

Question 35

how does ENSO work under el nino conditions

Answer 35

warm trade winds still push warm water from S america towards new guinea BUT persistent westerly wind pushes it back so warm pool is in the middle of the pacific ocean less cold upwelling, so s america gets warmer

Question 36

how do greenhouse gases work

Answer 36

– intercept outgoing radiation, but still allows most incoming radiation (IPCC 2015)

Question 37

name 4 greenhouse gases

Answer 37

co2, ch4, n20, HFCs

Question 38

primary driver of ghg emissions

Answer 38

energy sector

Question 39

define radiative forcing

Answer 39

the difference of insolation (sunlight) absorbed by the Earth and energy radiated back to space (W/m2 at top of Earth’s atmosphere)