1. Earth
Science in
a Rapidly
Changing
World
Kerry Sieh
Temasek JC 12 October 2012

2. Setting the stage

3. Mount Sharp, from the rover Curiosity,

4. Humanity’s
time-line
Millions of years ago

5. Technology has enabled humanity to grow to its current size
and Alexander Zehnder, 2011

6. The Earth is a bit crowded, isn’t it!
1802 1927 1961 1987 2013
1 billion 2 billion 3 billion 5 billion 7 billion

7. Four stories to illustrate what
earth scientists do to understand
our marvelous planet, and how
that contributes to safer and more
sustainable societies
Fidel Costa
Judith
Hubbard Wang
Xianfeng
Three assistant professors at the Earth Observatory of
Singapore

8. View towards the east, from
Borobudur temple
Merapi is just one of many active
volcanoes on Java. It’s particularly
famous because it sits just north of
the large Indonesian city of

9. Fidel
Merapi’s
Costa
biggest
historical
eruption, in
1865

10. An image of hot
pyroclastic flows
streaming down the
southern flank of
Merapi volcano in Nov
2010. This eruption
was larger than any
since just after 1865,
so the mapped hazard
zones were exceeded
and nearly 300 people
died
Yogyakarta has been
built on the gentle
slope of Merapi
Yogyakarta volcano. Old lahars
and pyroclastic flows
underlie the city, but
none have entered the
city in modern times.

11. Fidel
Costa
Why was the eruption of November 2010 the biggest since 1872?
Professor Fidel
Costa

12. Fidel
Costa
An water-rich
crystal in the 2010

13. Fidel
Costa
Prof Costa uses chemistry, physics and mathematics to
understand the “plumbing” of active volcanoes. This
photomicrograph shows the concentration of magnesium in an
amphibole crystal. Diffusion of the Mg across the crystal occurs
at certain rates. By measuring the amount the element has
diffused, he can tell how the story of how the crystal moved up

14. The earthquake cycle and generation of tsunamis

15. Pre-earthquake
(January 2005)
Post-earthquake
(May 2005)
Uplift during the Mw 8.7 earthquake of March 2005

16. We use GPS to measure tectonic and

17. Sumatran corals contain a record of large
earthquakes that extends back farther in time
than our modern instruments
Surveying the corals Cutting them and
taking them back to
the boat

18. From Sieh et al., 2008
Using the corals, I can
tell stories about ancient
earthquakes and their
patterns, even though
there were no
instruments there to
measure the
earthquakes. These

19. A record from corals that goes back 800 years
N
E
X
T

20. A recent effort by German colleagues
A recent effort by
I minute
German
colleagues to 4 minutes
estimate tsunami 7 minutes
inundation for an
10 minutes
earthquake I
forecast in 2008 after
arrival
Tools needed to at
do this: coast
Hydrodynamics,
a sub-discipline
of physics that is
mathematically
rigourous

21. Earth Observatory graduate students measuring
tsunami levels after the October 2010 tsunami.
These “field” measurements are important for
constraining hydrodynamic “models”
From a helicopter On the ground

22. Sediment in a coastal cave in Aceh, northern
Sumatra, records a 7,000 year long history of

23. Each of the light-colored layers represents a tsunami. The
dark layers are deposits of bat guano that accumulated on
the floor of the cave between tsunamis.

24. Using oil and gas exploration techniques to
understand earthquakes
Sichuan
basin
Professor Judith Hubbard

30. Chengdu

31. I think you all areof a changing climate –
Observations aware that the Earth’s
Greenland melting area
atmosphere and oceans are heating up

32. Greenland melting in 2012 First time NASA has
witnessed melting across the entire surface of the
ice sheet
July 8, July 12,
2012 2012
Image souce:
NASA
Light pink = areas of probably melt Dark pink = areas of certain melt

33. Sea level is rising

34. Temperatures are increasing in most places
Surface Temperature in 2001–2005 vs. 1951–80 ( C)
J. Hansen et al., PNAS 103: 14288-293 (2006)

35. Wang Xianfeng uses cave
formations to study past
climate change
Mineral-laden rainwater drips
onto the cave floor cave and
then the water evaporates,
Calcite (CaCO3) is the mineral
left behind. It forms stalagmites
that rise from the floor of the

36. Not all water (H20) is the same. H2180 is heavier than H2160
Most oxygen is 16O. It has 8 protons and 8 neutrons in
But about 0.2% of oxygen is 18O. It has 8 protons an
neutrons
Being heavier, H2180 doesn’t evaporate as easily as its lighter
cousin H2160. So rainwater is actually lighter than the seawater
from which it comes.
Consider now, what happens if this lighter rainfall does not return to the sea, but is
instead deposited in large glaciers. In this case, as the ice accumulates, the water in the
sea becomes more and more rich in 18O. That is, its 18O value increases.

37. From oxygen isotopes in plankton, we know this history of
temperature and CO2 for the past half million years!
Atmospheric CO2 (ppm)
Temperature stability of
the past 10,000 years
Source: Woods Hole Research Center, PEW Center on Global Climate Change

38. The Chongzhen Drought,
at the end of the Ming
Dynasty (1637-1643), is
known as one of the most
severe in Chinese history.
It affected more than 20
provinces in N and S China.
Huan The prolonged drought
g Here is Xianfeng’s record of
Chao rainfall changes in China for the helped Li Zicheng organize
past millennium, and inferences a popular uprising and
with respect to dynastic history overthrow Chongzhen in
Zhu
1644.
Yuanzhang,
River scene at Qingming festival, 1st Ming
emperor
The Huang Chao Li Zicheng
Uprising of the
870s and 880s
was fueled by a At the end of the Yuan Dynasty
drought, when there were a series of droughts
locusts swarmed During the Northern Song and a peasant uprising. In 1368
the land, and led Strong Monsoon Period, the Zhu Yuanzhang, the leader of
to the end of the Chinese population more than the uprising, took Beijing. His
Tang Dynasty tripled, rice became the staple of parents and older brother all
the Chinese diet and rice died during the droughts that

39. One “model” of projected annual average surface
temperature change
AD 2080-2099 minus AD 1980-1999
Average of 21 climate models forced by Scenario A1B. Multiply by ~1.2 for A2 and ~0.7 for
B1

40. How did all the
other species of
our genus
survive on our
wild planet over
the past couple
millions of years?

41. They didn’t have
agriculture.
Agriculture, upon
which our
civilization is
based, thrived in
the relatively
stable climate of
the past 10,000
years

42. Will we use the kind
of imagination,
intelligence, and
foresight that got us
… or continue to act as if here?
our Earth is static and
infinite in size and
resources?

43. Our fate is largely in your
hands! Study hard and
make a difference.

44. For those of you interested
in the Earth Sciences, NTU
will be offering a major
beginning in either 2013 or
2014.
We will also be offering a
minor for those of you with
other academic interests,
who wish to become
professionals and citizens
with a better comprehension
of natural hazards, climate
change, earth resources
and society

45. Thank you
New life starting after the 2004 tsunami on an emerged beach on