Climate change and Antarctic glaciology

Dr. Andrés Rivera

Laboratorio de Glaciología y Cambio ClimáticoCentro de Estudios Científicos (CECS), Valdivia

(Universidad de Chile, Santiago)

Key questions:

Climate change; natural variability or human induced?

Are the Antarctic glacier responses indicating ongoing

climatic changes?

What are the consequences of the Antarctic glacier

behavior?

It is possible to forecast/mitigate/manage the

consequences of glacier dynamics?

Global Atmospheric temperatures compared to 1951-1980 mean

Source: Hansen et al, PNAS. September 26, 2006

Greenhouse gases: Carbon dioxide (CO2)

CO2 in the recent past from air and ice core measurements

Year (AD)

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

CO

2 (p

pm

v)

200

220

240

260

280

300

320

340

360

380

South Pole Air SamplesLaw Dome Ice Core Data

CO

2 a

mo

un

t

Greenhouse gases: Carbon dioxide (CO2)

CO2 in the past from air and ice core measurements

Year (AD)

-400,000 -350,000 -300,000 -250,000 -200,000 -150,000 -100,000 -50,000 0

CO

2 (p

pm

v)

180

200

220

240

260

280

300

320

340

360

380

South Pole Air SamplesLaw Dome Ice Core DataVostok Ice Core Data

CO

2 a

mou

nt

Years before present400,000

300,000

200,000

100,000400,00 400,00 400,00 400,00 0

Greenhouse gases: Methane (CH4)2D Graph 1

Year

-4e+5 -3e+5 -2e+5 -1e+5 0

meth

an

e (

pp

bv)

200

400

600

800

1000

1200

1400

1600

1800

meth

an

e a

mou

nt

Years before present400,000

300,000 200,000

100,000 0

Temperature…

We know CO2 has increased through time

Wide discussion over potential for enhanced CO2 to alter global climate

What can we learn of this association by looking at past climate..?

Climate and greenhouse gases have been very closely connected

200

250

300

350

400

01x1052x1053x1054x1050

200

400

600

800CH

4

(right axis)

CO2

(left axis)

Years BP (before present)

CO

2 / pp

mv

CH

4 / pp

bv

-10

-5

0

5

Est

imat

ed T

diff

eren

cefr

om to

day

/ C

400,000 300,000 200,000 100,000 0Years before present

Esti

mate

d T

diff

ere

nce

from

tod

ay /

oC

CO

2 a

mou

nt

A

Meth

an

e

am

ou

nt

Take Home Message:

Ice core data shows us that:

CO2 concentrations are currently ~30% greater than in the previous 400,000 years

Methane is more than 2 times greater than in the previous 400,000 years

Clear association between changes in Greenhouse gases and changes in global temperature

ANTARCTICAThe seven continent; the coldest, windiest, highest, driest

13,5 millions of km2 (10 % of Earth surface)

98 % is ice covered

70 % of fresh water on Earth

91 % of ice on Earth

Equivalent to 65 m of sea level

Mean ice thickness: 2000 m

>4500 m of ice thickness in places

Ice velocities from 10 to 2500 m/year