Climppf1

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