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Emerging Strategic Research Theme
The Habitable Earth
Key themes
Sun Kwok
Faculty of Science
Causes of climate change
Ecological effects of climate change
Habitable planet in a wider context
Why this theme?
• It is perhaps the major challenge scientists
face in the 21st century and therefore of
tremendous practical importance
• It is scientifically interesting
• Requires interdisciplinary approaches
• Demonstrated record of research excellence
Members
• Causes of climate change
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Jonathan Aitchison
Jason Ali
Nathalie Goodkin
Z.H. Liu
G.C. Zhao
• Habitable planet in a wider
context
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Sun Kwok
Man Hoi Lee
Yiliang Li
Kono Lemke
Steve Pointing
• Ecological effects of
climate change
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David Dudgeon
Clement Dumont
Melissa Hart
Nancy Karraker
Leszek Karczmarski
Kenneth Leung
Vengatesen Rajan
David Thomson
Gray A. Williams
Rudolf Wu
Y.Q. Zong
Objectives
• To provide a sound and rigorous scientific
basis for global change
• To understand the changing interactions
between the physical and biological
components of the Earth system
• To understand the ecological implications of
climate change
Track record of the team (last 5 years)
High impact publications
• Science: 5
• Nature: 4
• Nature series: 3
• Proceedings of the National Academy of
Sciences: 3
median age of the team is: 43
Earth as an integrated system
• Atmosphere, hydrosphere, biosphere and
geosphere
• Interacting physical, chemical and
biological processes
• Human impacts (e.g., on habitat destruction,
biodiversity loss, atmospheric and ocean
composition)
Earth as a System
Atmosphere
Biosphere
Solid Earth
Oceans
Earth today
One of the greatest impact of NASA’s lunar program is the
public appreciation of how fragile the Earth is
Climate Change: Past and Present
• Global climate evolution
• Plate tectonics-climate
interaction
• Past atmospheric CO2
• Past Asian monsoon
variability
• HK regional climate change
• Asian monsoon-El Nino
interaction
34 M yr ago
Influences of assembly and breakup of supercontinents
on hydrosphere, atmosphere and biosphere
The assembly of a supercontinent may cause:
1. Decrease in total land areas
2. Low-rate oceanic production
3. Global sea level subsidence
4. Decrease of CO2 in atmosphere
5. Colder and dry weather - ‘Icehouse’
6. Mass Extinction – P/T Boundary Event
The breakup of a supercontinent may cause:
1. High-rate oceanic production
2. Global sea level rise
3. Increase of CO2 in atmosphere – continental/oceanic
rifting
4. Warmer and wet weather - ‘greenhouse’
5. Explosion of life – Cambrian explosion
Life and the Earth Environment
• When did the Earth become habitable, and
why did life boom in the Cambrian
period?
• How and when the Asian monsoon was
generated?
• How has vegetation responded to climate
change?
• Environmental changes in Hong Kong.
Impact of CO2 emissions
• Changes in atmospheric temperature leads
to ocean circulation, ocean/atmosphere
interactions, evaporation/precipitation
patterns
• Can the oceans sustain their role as CO2
sinks?
Ecosystems and population processes
• Impact of environmental change
on wildlife demography,
population structure, population
persistence, invasive species and
other multi-species interactions
(David Dudgeon, Gray Williams,
David Thomson, Kenny Leung,
Leszek Karczmarski, Clement
Dumont, Nancy Karraker)
Effects on organisms
• Individual effects of
environmental stress:
thermal, chemical,
osmotic, hypoxic,
acidification (Rudolf Wu,
Kenneth Leung, Rajan
Vengatesan, Gray
Williams, David Dudgeon)
Urbanization
• The urban heat island: analyses of spatial
variability and exposure (Melissa Hart)
• Building energy consumption under a
future warming climate (Melissa Hart)
Habitable planet in a wider context
• Life in extreme environments:
understanding the environmental limits for
life on Earth and how geochemical factors
determine the limits of life
• Origin of life
• Earth analogs: we cannot do experiments on
Earth. We need to learn from other
examples in the Solar System.
Habitable Earth in the Wider Context
• Extreme environments on Earth
as tractable analogs to inform the
search for life on other planets.
(Pointing, Li)
Polar desert, Earth
Polar desert, Mars
Habitable Earth in the Wider Context
• Synthesis, stability and concentration of biomolecules in
extreme environments on early Earth (Lemke, Li)
• The role of fluids in early life processes (Lemke, Li)
Habitable Earth in the Wider Context
•How do microbes interact with geo-materials?
Bio-mineralization (Li)
Ni-Cr-Fe-C alloy identified from 1600 million
years dolomite (Li unpublished data).
Habitable Earth in the Wider Context
• How does evolution of the Solar System affect Earth’s
Habitablity? (Lee)
• Habitable worlds elsewhere in the Solar System and the
Universe (Lee)
• The delivery of pre-Solar System organics and
their effects of the origin of life on Earth (Sun Kwok)
Extreme Environments
Deep Ocean
Atacama Desert, Chile
Permafrost Area
Salty
Lake
Grand Prismatic Spring
(Yellowstone)
Acid Mine Drainage
Summary
• There has been significant climate change
over the history of the Earth due to internal
and external perturbations
• The Earth is an integrated system
• Climate change is a complex subject
requiring input from geology, chemistry,
physics, biology, and astronomy