climppf1
TRANSCRIPT
CLIMATE CHANGE
PAST, PRESENT AND FUTURE
J.SRINIVASAN
DIVECHA CENTRE FOR CLIMATE CHANGE
INDIAN INSTITUTE OF SCIENCE
BANGALORE
This Book claims that Global warming is a hoax
Michael Crichton’s book refers specifically
• absence of real world data
•lack of model testing and validation
•lack of independent assessments of models
Planetary Emergency?
When scientists cannot predict tomorrow’s
weather accurately, how can they predict the
climate of the earth 50 years from now or what happened in the past?
With so much at stake, it is right that climate science is subjected to the most intense scrutiny.
Michael Le Page ,New Scientist.
Climate is different from weather
Weather• Time scale
– Hours-Days • Spatial scale
– Regional• Main Components
– Atmosphere
Climate• Time scaleMonths-Years-
Beyond• Spatial scale
Regional-Global• Main Components
Atmosphere, Ocean, Land… Humans
CLIMATE IS WEATHER AVERAGED OVER TIME
What controls climate?
• Land surface– Albedo– Evaporation– Temperature
• Oceans– Albedo– Evaporation– Energy transfer by ocean
currents & vertical mixing
• Greenhouse gases (water vapor,
CO2, O3)
• Solar radiation– Orbital controls– Latitude
• Clouds– Albedo– Atmospheric emissivity– Absorption and scattering
of solar radiation
• Aerosols– Absorption and scattering
of solar radiation– Condensation nuclei
Climate Change
• Natural -- Climate is in a continual state of flux due to natural causes
• Anthropogenic -- Humans as climate change agents
HOW DID THE CLIMATE OF THE EARTH VARY IN
THE PAST?
WHAT FACTORS CONTROLLED THESE
CLIMATE VARIATIONS?
Oscillation between ice-free and ice-covered earth
MULTIPLE EQUILIBIRUM
RADIATION
From Oerlemans and Van Den Dool, 1978
5 Billion years Earth’s history
• Mechanisms: Evolution of the Sun, Evolution of the Atmosphere
Important Greenhouse Gases
Water exists in solid, liquid and gas from only on earth
Greenhouse Effect
Climate in the Last 180 million years
• Mechanisms: Evolution of the Atmosphere, Plate Tectonics, Mountain Building, Volcanic Activity, Solar
Variability, Ocean Circulation
Mid-Cretaceous Climate (100 Ma)
http://alaskageology.org/polardinos.html
• Climate was warm during the Age of the Dinosaurs (the Mesozoic)– Alligators lived in Siberia!– Dinosaurs lived north of the Arctic Circle in
Alaska!
Long-term carbon cycle• Carbon added to atmosphere through metamorphic
outgassing and outgassing of volcanoes and mid-ocean ridges• Hydrolysis-weathering of silicate minerals in continental crust:
CaSiO3 + H2CO3 >> CaCO3 + SiO2 + H2O
• The products of continental weathering are transported to the oceans by rivers, where they are used to make CaCO3 and SiO2 shells of marine organisms. When these organisms die, many of them are deposited and buried on the seafloor. The carbon cycle is completed upon subduction and melting of these sediments. The melt may rise as magma, providing volcanoes and MORs with a source of recycled CO2.
Important flows of carbon on 100,000 year time scales
Last 1 million years
• Mechanism: Orbital Parameters
Last 120,000 years
• Mechanism: Orbital Parameters
Last 18,000 years
GISP2 Drilling Project
Extracting An Ice Core
Annual Layers In Ice Core
Oxygen Isotopes
• A small fraction of water molecules contain the heavy isotope 18O instead of 16O.
• 18O/16O ≈ 1/500
• This ratio is not constant, but varies over a range of several percent.
• Vapor pressure of H218O is lower than that
of H216O, thus the latter is more easily
evaporated.
18O• As water vapor is transported poleward in
the hydrologic cycle, each cycle of evaporation and condensation lowers the ratio of H2
18O to H216O, in a process called
fractionation.
• This ratio is expressed as 18O.
18O and Global Ice Volume
• As ice sheets grow, the water removed from the ocean has lower 18O than the water that remains.
• Thus the 18O value of sea water in the global ocean is linearly correlated with ice volume (larger 18O → larger ice sheets).
• A time series of global ocean 18O is equivalent to a time series of ice volume.
18O vs. Temperature
Figure 2.22: Variations of temperature, methane, and atmospheric carbon dioxide concentrations derived from air trapped within ice cores from Antarctica (adapted from Sowers and Bender, 1995; Blunier et al., 1997; Fischer et al., 1999; Petit et al., 1999).
The cooling and warming during the ice ages and interglacial periods, however, was far greater than would be expected from the tiny changes in solar energy reaching the Earth
Milankovitch Hypothesis
The change in Solar radiation was amplified many times by positive feedbacks
Solar Rad
TemperatureIncreases
Higher Greenhouse
Effect
CO2, CH4 and Water Vapor
increases
Ice becomes water
Absorbs more solar energy
POSITIVE FEEDBACK
POSITIVE
FEEDBACK
where X is ice mass,
Y is ocean temperature
Z is CO2
NON-LINEARITY &CHAOS
Complacent Attitude
From Union of Concerned Scientists
Sarmiento & Gruber 2002
Atmospheric COAtmospheric CO22 concentrations for the last millennium concentrations for the last millennium
The increase in CO2 will amplified many times by postive feedbacks
CO2 Temperature
Increases
Higher Greenhouse
Effect
Water Vaporincreases
Ice becomes water
Absorbs more solar energy
POSITIVE FEEDBACKS
POSITIVE
FEEDBACK
Before 1970, both natural and human factors could have played a role
The embedded systems VC by Florian Boor has been shifted to Hall 3 ICSR and will go on in the
FINGERPRINT OF ANTHROPOGENIC GREENHOUSE EFFECT
Satellite RecordsShow Stratospheric Cooling and
Warming!
Backlund et al in “U.S.Climate Change Program”
The Global Carbon Cycle
Humans
Atmosphere
760 + 3/yr
Ocean
38,000
Land
2000
~90
~120
~120
7 GtC/yr
~90
About half the CO2 released by humans is absorbed by oceans and land
“Suess Effect”The decline of C14 after the nuclear
tests demonstrates that CO2 entering the atmosphere through fossil fuel use
Over the last 25 years, Gangotri glacier has retreated more than 850 meters
How can we predict the
future climate of the Earth ?
General Circulation Models(GCMs)
Source: Jerry Meehl, National Center for Atmospheric Research
from www.realclimate.org
Source: National Center for Atmospheric Research
The planet is committed toa warming over the next 50 years regardless of political decisions
Adaptation Necessary
Mitigation Possible
•Widespread increase in extreme temperatures and rainfall
•Cold days, cold nights and frost will be less frequent
•Hot days, hot nights, and heat waves will be more frequent
Models predict increase in extremes
Heavy rainfall events (>10cm)
Very heavy rainfall events (>15cm)
Heavy precipitation events over Central India have increased during last 50 years
Source: IITM, Goswami et al. 2006; data is the frequency in each of 143 grids in the region
Light to moderate rainfall events (5-100 mm)
JJA RAINFALL CHANGE (%)
{2080-99 } – {1980-99}
NUMBER OF MODELS THAT PREDICT AN INCREASE IN RAINFALL
HOW WILL THE MONSOON ( JUNE,JULY AUGUST) RAINFALL CHANGE IN THE FUTURE ?
Courtesy: Courtesy: Katharine Hayhoe, Texas Tech University
.
84© 2008 Sustainability Institute
Summer Sea Ice in the Arctic
2008
2007
Lawrence and Slater 2005
-100
-50
0
50
100
150
1880 1900 1920 1940 1960 1980 2000
MS
L (
mm
)
Year
Tide Gauge Observations
Average Rate ~ 1.8 mm/year
0.8 mm/year
2.0 mm/year
3.2 mm/year
[Church and White, 2006]
Methane Release from Arctic Lakes
Burning methane over in Siberia (K. Walter)
Methane bubbles trapped in lake ice
Lakes boiling with methane in
the Arctic
0
10
20
30
40
50
60
70
Sea
-leve
l equ
ival
ent
(met
res)
Glaciers and ice caps Greenland Antarctica
West Antarctica
East Antarctica
Antarctic Peninsula
0
10
20
30
40
50
60
70
Sea
-leve
l equ
ival
ent
(met
res)
Glaciers and ice caps Greenland Antarctica
West Antarctica
East Antarctica
Antarctic Peninsula
Impact of glacier melting on sea levelImpact of glacier melting on sea level Impact of glacier melting on sea levelImpact of glacier melting on sea level
0.5m
7m
57m
Courtesy: SCAR
Millions at Risk from Parry et al., 2001
Tipping elements Processes, particularly sensitive to climate change
Arctic sea ice meltingArctic sea ice melting
Deep water Deep water formationformation
Antarctic ozone holeAntarctic ozone holeWest Antarctic West Antarctic ice sheetice sheet
Amazon Amazon vegetationvegetation
Marine Marine carbon cyclecarbon cycle
Indian Indian monsoonmonsoonSaharaSahara
El NiñoEl NiñoSouthern OscillationSouthern Oscillation
HimalayaHimalayasnow coversnow cover
Methane Methane outgasingoutgasing
Arctic ozoneArctic ozone depletiondepletion
Greenland Greenland ice sheetice sheet
Transition in Monsoon occurs within 25 years!Burns et al. (2003) Science 301: 1365-1367
Socotra Island (12°30’ N 54°E) Indian Ocean cave stalagmite proxy for monsoonal precipitation
Greenland ice core proxy for local temperature
Ocean Conveyor Belt
Adapted from IPCC SYR Figure 4-2
GEOENGINEERING
Rockström et al, Nature 24 Sep 2009
9 PLANTERY BOUNDARIESTransgressing one or more planetary boundaries may bedeleterious or even catastrophic due to the risk of crossing thresholds that will triggernon-linear, abrupt environmental change within continental- to planetary-scale systems.
Deutsches Museum (2003)
RENEWABLE ENERGY TECHNOLOGY
Conclusions• Climate Changes before 20th century on
account of natural causes• Global warming in 20th & 21st century primarily on account of human beings• No sense of urgency because it is
gradual• There can be nasty surprises• No catastrophic impact like Ozone hole
yet• Engineers need to be creative and
innovative to ensure transition to an economy based on renewable energy
THANK YOU
I AM READY FOR
A BARRAGE OF QUESTIONS
Risk of overshooting 2ºC target
Source: den Elzen and Meinshausen
Deforestation
From Anthes et al(2005)
From Giorgi , ICTP, Trieste
Global Mean Surface Temperature CRU
From Ben Santer
Deglaciation
Trends in Indian Monsoon Rainfall% change in 100 years, IITM,Pune