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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] res. in) Ph. D 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, O 2, O 3 depletion C • Global Biogeochemical Cycle- oceans C/B • Short-term Climate variability, Global Warming Should be covered in 7 -hours P/C/B
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, pages 530. • IPCC-AR 4, 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 Time Marks Mid-term exam 2 nd month of the class 30% Final-term 4 th month of 50% the class Assignments/Quiz Two/Three times 20% Total 100%
Earth system and climate: - A space-time perspective galactic Planets, Moon, stars -z on e k-years Li fe 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; 90 s~90 n West Longitude; 180 w~180 e 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. 977 x 1024 Kg Average density = 5517 kg/m 3 Rotation speed = 0. 729 x 10 -4 rad/sec Average surface temperature = 288 K, (150 C)
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 represents day-to-day variations in our atmosphere Climate is a long term average of weather (100 -years, 1000 -years, 50 years, 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 L ng o ve a w Earth t) ea (h S rt ho ve a w GH-effect helps the surface Temperature to be warm at 150 C = CO 2 and Other GH-gases
The status of present day green house gases and radiation budget. Concentration (ppm) Radiative forcing (w/m 2) Gas 1765 1992 Current Pre. Anth rate of industrial ropog increase (% enic per year) CO 2 278 356 0. 4 50 1. 4 CH 4 0. 7 1. 71 0. 6 1. 1 0. 48 CFC-11 0. 000268 0. 07 N 2 O 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 CO 2. Gas Relative Forcing CO 2 1 CH 4 21 N 2 O 206 CFC-11 12, 400 Addition of CH 4 has more impact than addition of CO 2. Addition of N 2 O has more impact than addition of CH 4
Present day CO 2; Keeling curve. © http: //en. wikipedia. org/wiki/File: Mauna_Loa_Carbon_Dioxideen. svg
Atmospheric CO 2 from 1700 to 2010
But ~50% of man-made CO 2 is absorbed by oceans and land. 20 % 50 % 30 % Oceans sink ~30% of anthropogenic CO 2 Terrestrial ecosystem absorbs ~ 20% of anthropogenic CO 2.
Annual mean CO 2 sinks and sources by terrestrial biospheres (~2 Pg. C/yr) Carbon. Tracker data from ESRL, NOAA, USA.
Annual mean CO 2 sinks and sources by the ocean (~2 Pg. C/yr) Shamil et al. , 2012, Atm. Chm. Phy. Discussions
1015 Gram Carbon/year CO 2 exchange between ocean & atmosphere, data developed at NIES, Japan. - 1. 5 x 1015 g. C/yr 1980 1990 2000 2010 Valsala et al. , 2010, Tellus-B,
Global warming or Global Cooling ? Schematic IPCC-AR 4 report, 2007
Human impacts on famines and mass deaths…(Ethiopian famine) Normal p hio Et 1984 -85 ia
Long term climate change: by Natural causes (observed- for 1 million years) Petit et al, 1999, Nature O 2 C r -P T xy o 700 -k 500 -k 300 -k Kilo-years 100 -k 0
Higher CO 2 leads to Higher temperatures Lower CO 2 leads to lower temperature But what causes variations in CO 2 ? 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 Human evolution 6 Cretaceous 30 Tertiary Quaternary 15 0 Oligocene Miocene Pliocene Quaternary 4 2 1 Miocene Pleistocene