Jordan, The Essential Earth 1e © 2008 by W. H. Freeman and Company Chapter 12: Climate and...

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Chapter 12: Climate and Glaciation

• Lonnie Thompson trekks to Himalaya, the Andes, and beyond to study ice.• Do you know why ? What is he studying ?

Chapter 10: Climate and Glaciation• No scientist has taken bigger risks above 18000 ft, risking blood clots, temporary blindness, frostbite, and hurricane-force winds.

• Risks to gather measurements and help us understand current climate trends.

• Lonnie Thompson reconstructed a meticulous calendar of temperatures and dates from isotope measurements in ice.

• He found that the Earth's frozen ice stores a history of climate changes as far back as 750,000 yrs.

The Earth's Climate

• What is climate ?

Climate is described by the average weather conditions at a point on the Earth's surface daily, yearly or longer.

The Earth's Climate

• The climate includes many components of the Earth's system and interactions between them.

The Earth's Climate

• The atmosphere is layered with different temperature values in each

• Temperatures in other Earth systems such as ocean water, biosphere, lithosphere, & crysophere all contribute to an average surface temp.

Glaciers

• The cryosphere comprises all of the ice on the Earth.

Glaciers

• Most of the Earth's ice is found in Antarctic continental glacier.• Where are some other continental glaciers ?

• Greenland is the second largest glacier on Earth and with Antarctica cover 10% of the Earth's land mass.

• These glaciers store 75% of the world's fresh water.

• While Greenland has 2.6 mill cubic km of ice, it is dwarfed by Antarctica which has 30 mill cubic km (90%) of the Earth's cryosphere.

• Antarctica's ice is ~4000 m thick!

Glaciers

• Snow melt is the source of much of the fresh water in the hydrosphere.

• Snowfall is 60-70% of all annual precipitation which melts in spring into rivers and streams.

Glaciers

• The cryosphere includes sea ice which grows in volume in the winter and shrinks in the summer.

• This satellite picture (left) shows sea ice flowing through the Bering Strait in May 2002.

Solar energy input to Earth’s surface is342 W/m2.

Heat flowing out of Earth’sdeep interior is only 0.06 W/m2.

Therefore, heat radiating from Earth must balance solar input.

• The Earth reflects radiation not absorbed by the atmosphere & surface• Strong greenhouse gases reflect this radiation back to the Earth and prevent it from leaving the atmosphere.

Heat and Radiation from the Sun

The Balance of Heat Flow into/out of the Earth

• Water vapor gives positive feedback, that is, it is a greenhouse gas and its presence prevents escape of the Earth's excess radiation.

• Albedo gives positive feedback. Albedo measures the Sun's reflected energy from the cryosphere. As the Earths' temp rises, and glaciers melt, the albedo decreases. This process reduces reflected radiation escape.

• Radiation damping can give negative feedback. Infrared energy escape is increased if temperatures rise. This process slows large temperature fluxuations and keeps the oceans from freezing or boiling off.

• Plant growth gives negative feedback. Conversion of CO2 into organic matter reduces greenhouse gasses in the atmosphere and allows for more escape of radiative energy.

What Would our Planet be like Without Greenhouse Gases ?

• The Earth rotates (1 day) much faster than the Moon (30 days) which evens out its temperature

• The Moon's temp changes from 130 C in the day to -170 C at night! This would be very uncomfortable!• The Earth's glaciers increases its albedo to 31% where the Moon's albedo is only 7%.

• However without any greenhouse gases, the Earth's surface temp would be very cold, -19 C (-2 F) and would freeze all our oceans.

• Some greenhouse gases are necessary to moderate strong fluctuations in surface temperature from Solar radiation

Local Climate Variations

Antarctic Ice Sheet

• Today many scientists work to study ice cores in Anarctica

• Russian scientists at Vostok station carefully remove an ice core at 3500m altitude (T is about -55C !)

• Below inspection of the core is done in a cold lab.

Past Glaciationfrom Ice Cores

Temperature relative to present climate

Thousands of years before present

Relative carbon dioxide

methane concentrations

Key:TemperatureCO2

Methane

There is a decline in both temperature and greenhouse gas concentrations during glacial periods… …and a rapid

rise duringdeglaciation.

Climate has been relatively warm andstable during the last 10,000 years.

Glacial and Temperature Cycles

• White shows evidence indicating the extent of the Wisconsin glacier in the Great Lakes during it's maximum about 18000 yrs ago and was ~3 km thick.

GEOLOGIC RESERVOIRS

Fossilorganiccarbon

Rockcarbonates

Fossil-fuel

burning(5.3 Gt/yr)

Cement production (0.1 Gt/yr)

Land-use change:

deforestation,agriculture(1.7 Gt/yr)

Land uptakeBy new plantgrowth(1.9 Gt/yr)

Ocean uptake by air-sea gas

exchange(1.9 Gt/yr)

Terrestrial biosphere

ATMOSPHERE

Human activities releasea total of 7.1 Gt of carbon into the atmosphere each year.

New plant growth andair-sea gas exchangeremove 3.8 Gt/yr,…

…yielding a netatmosphericincrease of3.3 Gt/yr.

Temperature

concentration

Global temperature anomaly

A recent warming trend correlateswith the increase in CO2.CO

2 concentration

Temperature

CO2 concentration

The 20th-century is clearly anomalous when compared with the last millennium.

Northern Hemisphere

temperature

anomaly (°C)

2 concentration

Arctic sea ice 1995-2007

(National Snow and Ice Data Center, Boulder)

Arctic sea ice 2005-2007

(National Snow and Ice Data Center, Boulder)

4.3 million sq km4.3 million sq km

Receding Glacier

South Cascade Glacier, Washington

Meteorites found in Arctic Glaciers• The easiest place to locate dark, rocky meteorites is in Antarctic Ice

Sheet• A small number of meteorites appear to have come from the Moon

and Mars• Several of these appear to have come from Mars

martian meteorite

lunar meteorite

Global Warming

• Global warming is a physical measurement that the Earth's surface temperatures are rising beyond normal fluctuations.

• Global warming can have many effects on our environment:

- increase atmospheric temperature- melt glacial ice- prevent escape of the Sun's excess radiation- harm habitat environments like polar bears- create drastic changes in our climate (extreme hot and cold seasons)- and remove our only evidence of past climate history !

What can we do about this at home ?

The Global Energy ChallengeRoel Snieder

Photo: USFWS/Susanne Miller

Developing countries

… and our energy use

How do Geologist Find Old Glaciers Boundaries ?

Glaciers leave clues ...

• Glacial striations on a rock from stones grinding at the base of a heavy ice sheet leave these shiny linear marks on the bedrock below.

Glacial Characteristics

• Glaciers flow downhill as a solid mass that creates channels, and walls made of ground up rock debris known as a merraine.

Erosional Landscapes

• Erosional landforms produced by valley glaciers include: – U-shaped valleys

– Hanging valleys

• Smaller tributary glacial valleys left stranded above more quickly eroded central valleys

U-shaped valleys

Hanging valleys

Erosional Landscapes

Glacial Deposits• Sediment-laden streams emerging

from ends of glaciers have braided channel drainage patterns

• Outwash landforms include drumlins, eskers, kettles and kames

• Drumlins give can tell us what direction a glacier moved.

The History of Energy Consumption in the US over past 150 yrs

How much oil is available in the world for our use ?Is it infinite ?

Peak oilPeak oil

N.B. based on USGS estimates, these are among the most optimistic (Energy Information administration)

Declining production (1)

resource depleted

Production

supply

Declining production (2)

production gap!

Production

demand

supply

Oil Peak, Oil Panic ?(Study by Amos Nur - Stanford)

U.S., Canada, Japan, Germany, France, Italy, UK, are the biggestconsumers of oil reserves worldwide.

Oil ConsumptionWorld wide by country

The US uses more oil thanall other countries combined

Countries with highest per capita income seeking oil from countries holding the oil wells/reservoirs (Saudi Arabia, Iraq, Venezuala).

New find in Gulf of Mexico(Jack No. 2 test well)

• up to 3-15 billion barrels of oil

• US consumption 20 million barrels/day

• 5 months - 2 years

• reservoir is 8 km under sea level

Non-convenional reserves(excluding gas and coal)

Produced (gone)

Proved Reserves

Undiscovered(?)

EORExtra Heavy Oil& Tar Sands Shale Oil

0 1 2 3 4 5 6 7 8 9 10

Trillions of Barrels Recoverable

Years Supply at2005 Production

Unconventional petroleum resources:(more difficult & dirty, and therefore expen$ive)

Conventional(“easy”)

0 25 50

(Courtesy of Joe Stefani)

Non-conventional oil

from National Geographic, June 2004

Tar Sand

HeavyOil

Oilshale

2 tons of tar sands produce 1 barrel of bitumen (~asphalt)

Other Energy Resources• The metal uranium is used to power nuclear power

generators– Found with organic matter in sedimentary rocks

– Accounts for 10% of U.S. energy production

– Leaves radioactive waste as by-product

• Hydroelectric power provides about 4% of U.S. energy needs– Renewable and non-polluting

• Geothermal power provides about 0.2% of U.S. energy needs

• Other renewable, non-polluting energy sources are wave/current power, solar power, wind power, and hydrogen fuel cells– As fossil fuel supplies dwindle, these sources become more important

Other Energy Resources• The metal uranium is used to power nuclear power

generators– Found with organic matter in sedimentary rocks

– Accounts for 10% of U.S. energy production

– Leaves radioactive waste as by-product

• Hydroelectric power provides about 4% of U.S. energy needs– Renewable and non-polluting

• Geothermal power provides about 0.2% of U.S. energy needs

• Other renewable, non-polluting energy sources are wave/current power, solar power, wind power, and hydrogen fuel cells– As fossil fuel supplies dwindle, these sources become more important

First solar 2 MW arrayFt. Carson, CO

Research: efficient solar cells

http://gcep.stanford.edu/research/solar.html

Alternative Energy Sources: Wind power

What can I do as consumer?

Lighting Transportation Appliances

What can I do as citizen?

• Ask: what is our energy plan?

• Start a discussion in your community.

• Demand that the United States becomes a world-leader in responsible use of energy.

“That which we are, we shall teach, not voluntarily but involuntarily.” [Emerson]

Jordan, The Essential Earth 1e © 2008 by W. H. Freeman and Company Chapter 12: Climate and...

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