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Textbook: The Earth System (3rd ed.) by L. R. Kump, J. F. Kasting, and R. G. Crane.

Available at the Campus Bookstore at Queens College Student Union.

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More LogisticsGrading: Homework 15%, 2 exams (20% each), Final Exam 30%, Class Participation 15% Homeworks: Homework sets (~three sets) distributed and collected at the start of the lecture.

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5

Tree’s Lecture 1Gaia’s HypothesisGlobal warming

6

Our Changing Planet

GAIA HYPOTHESIS

• the idea of the Earth as a single living superorganism

• James Lovelock• Gaia - a new look

at life on Earth, Oxford University Press, 1979.

The whole idea is:

The Earth as a single living superorganism that biosphere, the atmosphere, the lithosphere and the hydrosphere are in some kind of balance -- that they maintain a homeostatic condition.

This homeostasis is much like the internal maintenance of our own bodies; processes within our body insure a constant temperature, blood pH, electrochemical balance, etc.

The Gaia Hypothesis:

1) Earth is a self-regulating system

2) The system includes both life and the physical world

3) The system is capable of maintaining a surface environment that is suitable for life

We will use a model to understand and practice this theory in next a few lectures.

• Let’s first think about more immediate and practical questions, especially the topic of human-induced global warming

• To get us thinking about this, let’s consider what has happened the past two summer…

Global Warming

US summer heat wave smashes records– July 12, 2011

http://thewatchers.adorraeli.com/2011/07/31/wild-us-summer-heat-wave-smashes-records/

• Graph shows high daily temperature on July 12, 2011• 1,479 daily U.S. temperature records were broken in the month of July

http://www.businessinsider.com/texas-drought-2011-08

• In addition, the state of Texas was hit with its worst drought ever• Although there is no assurance that this drought has been self-induced, --indeed, it is blamed mostly on La Niña--this is precisely the kind of thing that is predicted to happen as the global climate warms

1945 1955 1965 1975 1985 1995 2005 20156.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

Year

Land

ave

rage

tem

pera

ture

(oC

)

PDSI

(Yi et al., 2013)

Land

Land warming

Land warming

Land dryingLand drying

PDSI = Palmer Drought Severity Index

What cause global warming?

CO2 typically hits a seasonal peak in the Northern Hemisphere

Atmospheric CO2 levels have never been as high as they are now during at least the past 800,000 years.

Atmospheric CO2 levels have never been as high as they are now during at least the past 800,000 years.

Atmospheric CO2 has seasonally approached 400 PPM on May 2, 2013!

Atmospheric CO2 has seasonally approached 400 PPM on May 2, 2013!

9.7±0.5PgC

Source: Peters et al. 2012a; Le Quéré et al. 2012; CDIAC Data; Global Carbon Project 2012

Fossil and Cement Emissions

Fossil fuel emissions

Land use

Fossil fuel emissions

Land use

How to divide this carbon cake by the

air, ocean and land?

How to divide this carbon cake by the

air, ocean and land?

Fossil fuel emissions

Land use

Fossil fuel emissions

Land use

Fossil fuel emissions

Land use

Fossil fuel emissions

Land use

Which part is more uncertain?

Which part is more uncertain?

Global Carbon Budget

The dashed land-use change line does not include management-climate interactions

The land sink was a source in 1987 and 1998 (1997 visible as an emission)Source: Le Quéré et al. 2012; Global Carbon Project 2012

Greatest variation in land carbon sink

Source: Le Quéré et al. 2012; Global Carbon Project 2012

Steadily increasingSteadily increasing

Huge fluctuation in land carbon sink!

Huge fluctuation in land carbon sink!

Hence atmospheric CO2Hence atmospheric CO2

What controls land carbon sink?

What controls land carbon sink?

Do these climate changes affect the net ecosystem exchanges of CO2 (NEE)?

We need find evidence from observations!!!

CarbonCO2

ClimateT

positive coupling

Positi ve or negati ve?

The temperature at northern-high latitudes will be increased much more than others near the end of 21th

century, as predicted by many climate models (IPCC, 2007)

Warming in the 21st Century

High latitudes

Projected decreases in precipitation are likely in most subtropical land regions near the end of 21th century, as

predicted by many climate models (IPCC, 2007)

Drying in the 21st CenturyLow latitudes

Eddy Flux Tower

CO2 H2O

CH4 T

CO2 H2O

CH4 TCO2 H2O

CH4 T

Eddy-Flux Tower

Does Climate Control NEE?

30

What are drivers of the vegetation distribution?

http://www.ncdsnet.net/~kinney/library/biome2.gif

Why so little carbon is here?

Too dry!!!

Why so much carbon is here?

Abundant rain and energy!

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

Photosynthesis

Using light converts carbon and water into sugars

Autotrophic respiration (plants respiration)

Heterotrophic respiration (soil respiration)

RespirationOrganic matter is converted back into CO2

Atmosphere

Biosphere

Photosynthesis

Photosynthesis > Respiration

Respiration

The ecosystem acts as A Carbon Sink

Atmosphere

Biosphere

Photosynthesis

Photosynthesis < Respiration

Respiration

The ecosystem acts as A Carbon Source