Transcript class1 - IISER Pune

Earth System and Climate:
Introduction (ESC-I)
Coordinators:
Dr. Vinu Valsala and Dr. Supriyo Chakraborty
Short introduction of instructor.
• Vinu K. Valsala (Vinu; E-mail:
[email protected])
• PhD in Ocean and Atmospheric Sciences
• Research interests
– Climate, Variability and Global warming
– Oceanography
– Numerical Ocean Modeling
– Ocean Biogeochemistry
Contents of ESC-Intro. course:
• Earth System Science and Global Climate Change G
• Global Energy Balance
P
• Global Carbon Cycle
C
• Recycling of Elements; C, N, O2, O3 depletion
C
• Global Biogeochemical Cycle- oceans
C/B
• Short-term Climate variability, Global Warming P/C/B
Should be covered in 7-hours
Text books:
• Lee R. Kump, J. F. Kasting and R. G. Crane, 2010: The
earth systems, Prentice-Hall Inc, pages-420
(*** Exams will be based on this; copies please make
available in Library).
• A. E. Gill, 1980, Atmosphere and Ocean Dynamics,
(Chapter-1 to 4), Int. Geo. Series, Vol.30.
• Sarmiento G. L., and N. Gruber, 2007, Ocean
Biogeochemical Dynamics, Princeton. Univ. Press, pages530.
• IPCC-AR4, 2007, Climate Change, The Physical Science
Basis, Chapter-2, Technical Summary. PDF copy
available at http://www.ipcc.ch/publications_and_data
Other materials:
• Please prepare class notes by yourself.
• We will provide you our ppt slides (in a
common server)
• No DICTATION of class notes (you are grown
enough for this introductory course !)
• Assignments/Quiz,
– computer exercises of plotting the data,
interpretations.
Examinations and evaluation
Type
Mid-term exam
Final-term
Assignments/Quiz
Time
2nd month
of the class
4th month of
the class
Two/Three
times
Marks
30%
Total
100%
50%
20%
Let’s Start!
Earth system and climate:- A space-time perspective
galactic
Planets,
Moon,
stars
k-years
years
days
Daily
life
Sunny
/Rain
hours
minutes
μ
ν
An
year/
1000
km
Climate
Weather: day-to-day states of the
Atmosphere (environment)
Climate: A long term average of the
C
states of the atmosphere.
10-7 100 102 103 105 107
ν μ
meter
km
k-km
1010
galactic
Terminologies to remember:
Geometry of earth
North pole
Latitude;
90s~90n
West
Longitude;
180w~180e or
00 ~ 3600
East
Equator = 00
South pole
Some useful quantities to remember
Shape of the earth: Oblate spheroid
Image courtesy : Wikipedea
Radius of the earth: 6371 Km (6378.14 - 6356.8)
Mass of the earth: 5.977x1024 Kg
Average density = 5517 kg/m3
Rotation speed = 0.729x10-4 rad/sec
Average surface temperature = 288K, (150C)
Regional characterizations:
•
•
•
•
Tropics
Sub-tropics
Mid-latitude
Polar
Tropical climate
Temperate Climate
Polar Climate
Weather and Climate.
01-Augst to 08-August
temperatures over a
Particular location 
Weather
Weather represents
day-to-day variations
in our atmosphere
Climate is a long term
average of weather
(100-years, 1000-years,
50years, 30 years)
Major three themes that we address in this
course is.
• The earth system itself, as a combination of
Biota, Atmosphere, Hydrosphere and Solid
Earth.
• What causes current global climate change
• Climate is changing ever since the earth is
formed 4.6 billion years ago. There are
episodic ice-ages and interglacial warm
periods. So, if the current climate is not
warmed by humans, are we going back to
ice-ages?
Schematics of earth system
Schematics showing interactions between various
Components of Earth system.
Evidences of global change on short time
scales.
Global Climate change.
Global average observed surface temperature
trend
From IPCC Assessment Report 4 (AR-4), 2007
What causes in global temperature change in
last 100 or 200 years?
• Are they part of any natural change?
• Are they induced by humans (Anthropogenic?)
• Anthropogenic causes of climate change
• Fossil fuel burning
• Deforestation
• Ozone layer depletion
• What are the natural reasons for climate change?
The Green house effect.
Sun
Earth
GH-effect helps
the surface
Temperature to
be warm at 150C
= CO2 and
Other GH-gases
The status of present day green house
gases and radiation budget.
Concentration (ppm)
Radiative forcing (w/m2)
Gas
1765
1992
Current
PreAnthr
rate of
industrial opoge
increase (%
nic
per year)
CO2
278
356
0.4
50
1.4
CH4
0.7
1.71
0.6
1.1
0.48
CFC-11
0.0
0.000268
0.0
0.0
0.07
N 2O
0.275 0.31
0.25
1.25
0.15
Sarmiento and Gruber, 2007, Ocean BGC Dyn.,
Radiative forcing per additional molecule
relative to the radiative forcing due to
one additional molecule of CO2.
Gas
Relative Forcing
CO2
1
CH4
21
N2O
206
CFC-11
12,400
Addition of CH4 has more impact than
addition of CO2.
Addition of N2O has more impact than
addition of CH4
Present day CO2; Keeling curve.
© http://en.wikipedia.org/wiki/File:Mauna_Loa_Carbon_Dioxideen.svg
Atmospheric CO2 from 1700 to 2010
But ~50% of man-made CO2 is
absorbed by oceans and land.
20 %
50 %
30 %
Oceans sink ~30% of
anthropogenic CO2
Terrestrial ecosystem
absorbs ~ 20% of
anthropogenic CO2.
Annual mean CO2 sinks and sources by
terrestrial biospheres (~2 PgC/yr)
CarbonTracker data from ESRL, NOAA, USA.
Annual mean CO2 sinks and sources by
the ocean (~2PgC/yr)
Shamil et al., 2012, Atm. Chm. Phy. Discussions
1015 Gram Carbon/year
CO2 exchange between ocean & atmosphere,
data developed at NIES, Japan.
- 1.5x1015 gC/yr
1980
1990
2000
2010
Valsala et al.,
2010, Tellus-B,
Global warming or Global Cooling ?
Schematic
IPCC-AR4 report, 2007
Human impacts on famines and mass
deaths…(Ethiopian famine)
Normal
1984-85
Long term climate change: by Natural causes
(observed- for 1 million years)
Petit et al,
1999,
Nature
700-k
500-k
300-k
Kilo-years
100-k
0
Higher CO2 leads to Higher temperatures
Lower CO2 leads to lower temperature
But what causes variations in CO2 ?
Earth system as a self-regulatory system.
What are the natural causes of long term climate
change? Milankovitch cycles (periodic)
Precision
 19-23 k-yrs
Tilt
 41-42 k-yrs
Eccentricity
100-400 k-yrs
What are other natural causes of radiation
budget change? (aperiodic)
= eradication of life;
Are we driving next
eradication?
Millions of years ago
Continental drifts
400
350
Devonian
300
Carboniferous
250
Permian
200
150
100
50
0
Climate
Triassic
60
Paleocene
8
Jurassic
45
Eocene
6
Cretaceous
30
Tertiary
Quaternary
15
0
Oligocene
Miocene
Pliocene
Quaternary
4
2
1
Human
evolution
Miocene
Pliocene
Pleistocene