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Chapter 23
Global Change in the Earth System
LECTURE OUTLINE
earth
Portrait of a Planet
Third Edition
©2008 W. W. Norton & Company, Inc.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Change in the Earth System
Prepared by
Ronald Parker
Earlham College Department of Geosciences
Richmond, Indiana
Global Change
Geology verifies that the Earth constantly changes.
 Why does it constantly change?

A plastic asthenosphere permits tectonic plate motion.
 A star is close enough to warm Earth and its atmosphere.
 Temp. permits liquid water, thus, weathering and erosion.
 Biotic evolution has transformed the planet.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Goldilocks Effect

Venus is too close to the Sun.
No liquid water; no way to remove atmospheric CO2.
 Runaway greenhouse conditions – Too hot for life.


Mars is too far from the Sun.
All water is frozen.
 No atmospheric CO2 to trap heat.


As in the story of Goldilocks, Earth is “just right.”
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Earth System

Life on Earth is due to interaction between the…
Lithosphere.
 Atmosphere.
 Hydrosphere.


The “Earth System” is comprised of these physical
components interacting with the biosphere.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Earth System
The interlinkage of the physical and the biological.
 Global changes transform or modify both realms.


There are many ways to describe changes.
Rate – Gradual vs. catastrophic.
Frequency – Unidirectional vs. cyclic.
Agency – Geogenic vs. anthropogenic.

Change occurs in both a unidirectional and a cyclic manner.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Unidirectional Changes

Evolution of the solid Earth.
Planetesimal accretion.
 Melting and differentiation.

Iron sank to the center.
Produced a layered Earth.
Iron alloy core.
Rocky mantle.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Unidirectional Changes

Evolution of the solid Earth.

Formation of the Moon.
Mars-sized proto-planet collides.
Mantle blasted into space.
Debris coalesces to form the Moon.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Unidirectional Changes

Evolution of the atmosphere and oceans.
Volcanic gases created an early atmosphere.
 Liquid water condensed to form the oceans.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Unidirectional Changes

Evolution of the atmosphere and oceans.
Life appeared quickly on Earth, by 3.8 Ga.
 Living organisms modified the entire surface of Earth.

Changed the composition of the atmosphere.
Altered the chemistry of the oceans.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Unidirectional Changes

Evolution of life.
Living organisms were entirely single-celled until ~ 700 Ma.
 Rapid diversification followed development of…

Aerobic, eukaryotic cells.
Multicellular organisms.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Physical Cycles

The supercontinent cycle.
Plate tectonics drives a dance of the continents.
 Ocean basins open and close.
 Continental land masses collide and rift apart again.
 Supercontinents (like Pangaea) have formed several times.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Physical Cycles

The sea-level cycle – SL is geologically unstable.
SL has gone up and down many times in Earth history.
 Transgression (SL rise): shorelines invade land.
 Regression (SL fall): land is re-exposed.
 T–R cycles are bounded by unconformities.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Physical Cycles

The sea-level cycle – SL is geologically unstable.

SL has gone up and down many times in Earth history.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Physical Cycles

The rock cycle –There are 3 types of rock.
Igneous – Cooled from a melt.
 Sedimentary – Made of eroded particles.
 Metamorphic – Rocks altered by heat and pressure.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Physical Cycles

Contrary to popular belief, rocks are not permanent.
One rock type may transform into any other type.
 Thus, the atoms in rocks are constantly being rearranged.
 Require long periods
of time.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Biogeochemical Cycles
Chemical fluxes between living and nonliving.
 Involve storage and transfer between reservoirs.


Nonliving reservoirs.
Atmosphere.
Lithosphere.
Hydrosphere.

Living reservoirs.
All living organisms.
Microbes.
Plants.
Animals.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Biogeochemical Cycles

Many chemical compounds engage in these cycles.
Some interactions are essential for life (Calcium).
 Some interactions are toxic (Mercury).
 Some may be either, depending on amount (Molybdenum).

Rates of transfer between reservoirs vary widely.
 Examples.

Carbon.
 Nitrogen.
 Sulfur.
 Metals.
 Trace elements.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Biogeochemical Cycles

The hydrologic cycle:

Water moves between biological and physical reservoirs.
Biological.
All living organisms.
Physical.
Oceans.
Atmosphere.
Surface water.
Ground water.
Glaciers.
Soil moisture.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Carbon Cycle

A biogeochemical cycle that regulates climate.
Volcanic CO2 adds carbon to the atmosphere.
 Atmospheric CO2 is removed in several ways.

It dissolves in water.
Carbonic acid.
Bicarbonate.
Photosynthesis
removes CO2.
Weathering.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Carbon Cycle

Carbon may be stored for long periods of time.
Limestones.
 Fossil fuels (coal and oil).
 Organic shales.
 Methane hydrates.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
The Carbon Cycle

Carbon is returned to the atmosphere.
Biotic respiration creates CO2 from organic matter.
 Rapid oxidation (burning) of organic matter creates CO2.
 Metamorphism of carbonate rocks liberates CO2.
 Degassing removes dissolved CO2 from water.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Earth’s climate changes over geologic time scales.

Long-term climate change.
Millions to 10s of millions of years in scale.

Short-term climate change.
10s to 100s of thousands of years in scale.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Climate studies reveal our past, suggest our future.
Kinds of climate changes.
 Rates at which these changes occur.
 Effects of climate changes on Earth and its inhabitants.


Methods of study.
Paleoclimates – Investigations of past climatic variation.
 Computer simulations – Modeling past and future changes.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates – Past climates are indicated by
datable Earth materials that are climate-sensitive.

Stratigraphic records – Sequences of rock strata.
Depositional environments are often climate-sensitive.
Coral reefs – Tropical marine.
Glacial tills – Cold and continental.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimatic evidence:

Paleontological – Faunal assemblages are climate-sensitive.
Assemblage changes record climatic shifts.
Pollen in pond sediments.
Spruce (colder) vs. hemlock (warmer).
Trees (colder, drier) vs. grasses (warmer, wetter).
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates:

Oxygen isotopes – 2 isotopes: 16O and 18O.
16O water evaporates faster than 18O water.
During ice ages…
16O in seawater evaporates faster.
This water is trapped on land as ice.
Seas become 16O depleted, 18O enriched.
18O/16O increases.
During interglacials…
Melting ice returns water to oceans.
16O returns to oceans.
18O/16O decreases.
 Ice core 18O/16O data track climate
over 400 Ka.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates:

Oxygen isotope ratios are preserved in carbonate shells.
The oxygen in CaCO3 shells mirrors oceanic 18O/16O.
Changes in ocean chemistry are preserved in sea floor strata.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates:

Bubbles in ice – Tiny air pockets trapped in glacial ice.
Form at the time the snow turns to ice.
Analysis of trapped air reveals atmospheric chemistry.
Changes with depth in ice = changes over time.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates:

Growth rings – Tree rings can easily be dated.
Ring thickness reflects climatic changes.
Wetter, warmer = thicker; drier, colder = thinner.
Ring widths form time sequences.
Overlapping sequences yield a time scale.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Global Climate Change

Paleoclimates:

Human history – Climatic changes recorded by people.
Written history.
Art history.
Archaeological history.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Long-Term Climate Change

Global climate history has been
largely deciphered.
Greenhouse – Warmer climates.
 Icehouse – Colder climates.


Last 100 million years.
Warm climate at the end of Mesozoic.
 Climate cooling since Oligocene.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Long-Term Climate Change
What causes long-term climate changes?
 Complex interactions across the Earth system.


Plate tectonics modifies the position of continents.
Oceanic currents – Closing the Isthmus of Panama.
Determines locations that are high or low.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Long-Term Climate Change

What causes long-term climate changes?

Volcanic gases trap heat, promote global warming.
Mid-Cretaceous rifting and expanded mid-ocean ridges.

Orogenic uplift consumes CO2 in rock weathering.
Leads to overall climatic cooling.
Uplift of the Himalayas attended Cenozoic cooling.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Long-Term Climate Change

What causes long-term climate changes?

Biological influences.
Formation of organic deposits removes CO2.
Coal.
Oil.
Natural gas.
Evolution.
Appearance of lichens in the Neoproterozoic.
Appearance of grasses in the Miocene.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Long-Term Climate Change

CO2 and CH4 are greenhouse gases.
Transparent to incoming UV radiation from the Sun.
 Absorb infrared energy re-emitted from Earth’s surface.


Greenhouse gases exert a strong control on climate.


More GHG – Warmer; Less GHG – Cooler.
Processes that add or remove GHGs alter climate.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

The past million years – Dramatic climate flux.
5 major glaciations.
 20 to 30 minor glaciations.
 Separated by interglacials.

Warmer or colder climates may last 1,000s of years.
 Climate shifts may occur in as little as a decade.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

The past 15,000 years (the Holocene).
Warming led to deglaciation, yet temps still fluctuate.
 Several cold periods have punctuated this interglacial.

Younger Dryas.
Holocene maximum.
Medieval warm period.
Little ice age.
Modern warming trend.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

Fluctuations in solar and cosmic radiation.

Solar output varies with the sunspot cycle.
Sunspot activity spikes every 9 to 11.5 years.
Increased sunspots attend a decrease in solar output.

Changes in the natural cosmic radiation flux…
May cool Earth by increasing high-altitude clouds.
May warm the Earth by increasing low-altitude clouds.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

Changes in Earth’s orbit and tilt.

Milankovitch factors.
Earth’s axis wobbles (precession).
23,000-year periodicity.
Angle of axis (obliquity) changes.
41,000-year periodicity.
Shape (eccentricity) of orbit varies.
100,000-year periodicity.
 These factors alter insolation.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

Changes in volcanic emissions.
Atmospheric reflectivity due to clouds (albedo) varies.
 Volcanic aerosols significantly contribute to albedo.

Tambora (1815) resulted in the “year without a summer.”
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

Changes in oceanic currents.
Ocean currents distribute equatorial heat to the poles.
 Disruption of currents could initiate cooling.

Currents are driven by thermohaline sinking at the poles.
Melting sea ice could alter the salt-density underflow.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Short-Term Climate Change

Global changes in greenhouse gas concentrations.

Sudden addition or removal of GHGs could alter climate.
Sudden release of methane hydrates from ocean sediments.
Changes in the amount of photosynthesizers (algal blooms,
deforestation, etc.) could change CO2 concentrations.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Climate Change

Catastrophic events – Occur very rapidly.
Local – Volcanic eruptions, earthquakes, tsunamis, etc.
 Global – Bolide impacts, flood basalts.


Catastrophic events may induce mass extinctions.

K-T (Cretaceous – Tertiary) boundary event.
End Mesozoic extinction (dinosaurs and many others).
Coeval with an asteroid impact on the Yucatan peninsula.
Debris from the Chicxulub impact may have blocked the Sun.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Climate Change
Extinction events – The stratigraphic record contains
evidence of dramatic decreases in biodiversity.
 Large numbers of species disappear forever.
 Major extinctions.

Late Ordovician.
 Mid-Late Devonian.
 End Permian.
 Late Triassic.
 End Cretaceous.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Prehistoric humans were few having a small impact.
 Today, humans are a huge force of planetary change.

Exponential population growth aided by revolutions in...
 Industry, agriculture, technology, and medicine fueled by...
 A suitable supply of natural resources.


Humans may rival or exceed some natural processes.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Landscape modifications.

Human-induced erosion may exceed natural processes.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Ecosystem modification – Balances are destabilized.
Human changes occur faster than organisms can adapt.
 Rainforest decline is largely the result of human agency.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Ecosystem modifications – Destroy habitats.
Deforestation.
 Overgrazing.
 Agriculture
 Urbanization.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Pollution – Materials that are in the wrong place.
 Modern human society generates contaminants.

Solid, liquid or gaseous materials that overwhelm natural
attenuation mechanisms and degrade their locales.
 Contaminating materials are diverse.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Pollution – Air quality.

Smog (smoke + fog) – Urban haze created by reaction of…
Ground-level ozone, and…
Unburned hydrocarbons.
Catalyzed by sunlight.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Pollution – Water contamination.

Pollutants frequently enter surface water and groundwater.
Sanitary wastes.
Fuel and oil.
Solvents.
Fertilizers.
Pesticides.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Pollution – Acidification.

Acid runoff – Sulfide mineral oxidation releases acid.
Coal mining.
Base metal mining.

Acid rain – Sulfate-rich aerosols
acidify rain.
Coal-fired power plants.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Pollution – Radioactive waste.

Nuclear materials mining and processing generate wastes.
Mine spoil and mill tailings.
High-level nuclear wastes.
Medical radioactive isotopes.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Pollution – Stratospheric ozone (O3) depletion.
Chlorofluorocarbons (CFCs) catalyze destruction of ozone.
 Stratospheric ozone protects Earth from UV radiation.
 Ozone depletion is potentially harmful to life.
 Note: Ozone depletion is unrelated to CO2 buildup.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Are human GHG increases
causing global warming?
 Most scientists agree that the
answer is “Yes!”

Human agency has greatly
increased CO2 and CH4
concentrations.
 The rate of addition jumps
markedly at the start of the
industrial revolution.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Human GHG increases ARE causing global warming.

CO2 in the atmosphere has steadily climbed since 1958.
In 1958, CO2 was ~ 315 ppm; in 2000, CO2 was ~ 370 ppm.

CO2 varies seasonally by ~5 ppm due to plant activity.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Are human GHG increases causing global warming?
 Data amassed over 3 decades supports a “yes.”


Disintegration of Antarctic ice shelves.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Melting of the Greenland ice
sheet is accelerating.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The sea ice covering the Arctic Ocean is shrinking.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Valley glaciers are retreating rapidly worldwide.
 The sea ice covering the Arctic Ocean is shrinking.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Maple sap runs earlier.
 The mosquito line (elevation marking survival) has risen.
 Polar bears are threatened by loss of pack ice for hunting.
 Area of permafrost has substantially decreased.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Intergovernmental Panel on Climate Change (IPCC).
Founded in 1988 by the United Nations.
 Reviews climate science.
 Publishes an assessment of the science every 5 years.
 Fourth Assessment Report (2007) indicated…

Climate warming is happening.
We know a lot more then we did a few years ago.
Humans are a substantial cause of warming.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes
Most scientists accept global warming as fact.
 Fewer dispute warming as data accumulates.


Surface air temperatures have warmed by 0.9oC since 1880.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Since 1920, global temperature has increased.

1900s warming has reversed a 1,000-year cooling trend.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The global warming debate has largely shifted.


From “if” warming is occurring, to the magnitude of effects.
Computer models help to predict climate changes.
By 2050, average annual T will increase by 1.5oC to 2.0oC.
 By 2150, global T may be 5oC to 11oC warmer than present.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The predicted effects of global warming.

A shift in climate belts.
Ecozones will shift toward poles.
Deserts will expand.
Less soil may be fertile.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The predicted effects of global warming.

Stronger storms due to a more vigorous hydrologic cycle.
Higher sea surface temps.
Greater evaporation.
Greater differential pressures.
2005 set a number of storm records.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The predicted effects of global warming.

A rise in sea level.
Sea level is now rising 1-2 mm/year.
Warming will accelerate this trend by…
Thermal expansion of seawater.
Melting polar ice.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

The predicted effects of global warming.

A rise in sea level.
Many people live within a meter of SL.
Rising SL will displace millions.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Anthropogenic Changes

Many scientists think that warming might lead to…
Interruption of the oceanic circulation system.
 Warm water moves poleward to replace polar deep water.
 Disrupting the fall of polar water may idle warm return flow.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Earth’s Future

Our future on Earth requires sustainable growth.

Prosperity based on balancing societal and human needs.
The limitations of Earth’s finite resources.

Without sustainability, humans will be in trouble.
Earth system disruption will reach a critical point based on...
Natural resource limitations (fuels, metals, water).
Shrinking land areas.
Increasing populations.
Under such a scenario, Earth will dictate a new equilibrium.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Earth’s Future

In millions of years, Earth’s surface will differ.
Plate tectonic will reshuffle continents.
 Erosion will reshape the landscape.
 Seas will invade or expose land.


Homo sapiens is not likely to remain. Our options?
Extinction.
 Evolution.

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
Earth’s Future

In billions of years, Earth will be vaporized.
The Sun will run out of hydrogen.
 It will collapse inward.
 Collapse will heat it.
 It will expand outward.
 The red giant phase of
the Sun will expand
past the orbit of Earth.
 Earth will vaporize.
 C’est la vie!

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System
This concludes the
Chapter 23
Global Change in the Earth System
LECTURE OUTLINE
earth
Portrait of a Planet
Third Edition
©2008 W. W. Norton & Company, Inc.
Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak
Chapter 23: Global Change in the Earth System