Lect 9

Question 1

Sulphate aerosols

Answer 1

Black soot emitted from chimneys etc
-SO2 = predominant anthropogenic source (oxidised to SO4)
Unpolluted marine layer = pp t
Urban levels = pp b
-must enter stratosphere to affect climate

Question 2

Yok G sulphate t

Answer 2

No trend w/ anthropogenic aerosol emissions pre-industrial
-no trend in C.Am rainfall
Since 1850:
Huge anthropogenic incr.
= N.Hemi aerosols shift ITCZ South = dry Yok records

Question 3

Volcanic sulfur-climate Effect

General concept

Answer 3

-volcanic aerosols reflect solar UV in summer = summer cooling
-reflect outgoing IR in winter = winter warming
RESULTS IN HUGE INSOLATION CHANGE IN SHORT TIME PERIOD
•low latitude eruptions = most impactful

Question 4

Volcanic sulfur-ITCZ Effect

Answer 4

S.Hemi eruptions shift ITCZ to North and S.Hemi cools = > rainfall

N.Hemi eruptions shift ITCZ to South and N.Hemi cools = drying

Question 5

Pinatubo

Answer 5

Well studied eruption

-ash column penetrated 37km into atmosphere

Question 6

Ice Cores as a proxy

Answer 6

Record sulphate emissions;
GISP2 Record:
-can see anthropogenic input
-can see Tambora, Pinatubo and 1812 unknown eruption

Question 7

Yok G as a proxy

Answer 7

Correlates to GISP2 nicely

-can see Laki eruption

Question 8

Laki eruption

Answer 8

122 Mt of sulphur dioxide released
—> 95 Mt into stratosphere
Impact:
-Europe cooled big time: N.Hemi Temp decreased by 1 deg in < year.
-22% Icelandic dead

R.Nile sed record:
[nile fed by ITCZ. If ITCZ in S.Hemi then Nile receives less water]
Laki shifted ITCZ South so water level decr. Seen in Nile record

Question 9

Yok I proxy

Answer 9

Records N.Hemi volcanic eruptions;

—> Mayan megadrought caused by Changbashain volcanic eruption (also coincides w/ sunspot minima)

Question 10

NAO/ITCZ-Volcanic link

Answer 10

NAO record vs Yok 1 indicates periods of volcanism-> NAO +ve & -ve fluctuations

N.Hemi eruptions = ITCZ to South = N.Hemi cooling.
—>Hadley Cell/Azores High = in the South = NAO -ve
& VICE VERSA

Question 11

LGM Eruptions

Answer 11

Toba: largest Quaternary eruption

• mag 8 eruption w/ Caldera size of Durham
• climatic response unclear

Laachersee

Question 12

Toba eruption (stalag records)

Answer 12

Mag.8, massive caldera.
Climate response unclear

Records;
Secret Cave, Borneo: shows significant drying for 800 yrs post eruption = ITCZ shifted to South
El Condor, Peru: shows incr. rainfall for 800 yrs post eruption = ITCZ shifted South

Question 13

Toba eruption (ice Cores)

Answer 13

NGRIP and EDML show:

Toba = long term Greenland Cooling and long term Antarctic Warming == ITCZ shifted to South

Question 14

N.Hemi volcanics-Greenland Climate link

Answer 14

8 radiometrically dated eruptions from 30-80ka = all linked to Greenland stadial (cooling) events

Monte Carlo simulations= >95% significance

Question 15

S.Hemi volcanics-Greenland climate link

Answer 15

Only 5 radiometrically dated eruptions from 30-80ka
Correlate to Greenland warming events (DO events/interstadials)

Not enough eruptions to test significance

Question 16

Laachersee Hypothesis

Answer 16

German volcano erupted (2x pinatubo) at 12.8k BP

Resulted in asymmetric cooling; N.Hemi would’ve cooled massively

Evidence: sulfur spikes & platinum in GRIP confirm timing