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MET 112 Global Climate Change - Lecture 4. Natural Climate Forcing Dr. Eugene Cordero San Jose State University. Outline – Earth’s early history Evolution of the atmosphere Temperature variations Activity. Articles we’ve been reading…. 0 of 5. :15.

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Met 112 global climate change lecture 4
MET 112 Global Climate Change - Lecture 4

Natural Climate Forcing

Dr. Eugene Cordero

San Jose State University

Outline –

  • Earth’s early history

  • Evolution of the atmosphere

  • Temperature variations

  • Activity

MET 112 Global Climate Change



In this weeks reading the main topic of the article from new zealand is about

0 of 5

:15

In this weeks reading, the main topic of the article from New Zealand is about

  • Changes in CO2

  • Changes in CH4

  • Changes in solar radiation

  • Transport of oil

  • Transport of water

  • Changes in air pollution

  • Both 1 and 4

  • Both 1 and 5

  • Both 1 and 6

MET 112 Global Climate Change


Who is the primary funder of the american enterprise institute aei

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:20

Who is the primary funder of the American Enterprise Institute (AEI)

  • NASA

  • ExxonMobil

  • Google

  • HP

  • PrimeAmerica

  • ESPN

  • CNN

MET 112 Global Climate Change


Temperature graph
Temperature Graph

Source:

http://www.ruf.rice.edu/~leeman/aNR.html


Water restrictions in australia
Water restrictions in Australia

Source:

http://www.melbournewater.com.au/content/water/water_storages/stage_3_water_restrictions_-_questions_and_answers.asp



Natural climate change

External Forcing:

Internal Forcing:

Natural Climate Change

The agent of change is outside of the Earth-atmosphere system

  • The agent of change is within the Earth-atmosphere system itself

MET 112 Global Climate Change


External forcing

Variations in solar output

Orbital variations

Meteors

External Forcing

MET 112 Global Climate Change


Solar variations

Sunspots are the most familiar type of solar activity.

Solar Variations

  • Sunspots correlate with solar activity

    • More sunspots, more solar energy

MET 112 Global Climate Change



Solar activity
SOLAR ACTIVITY

  • Sunspots are the most familiar type of solar activity.


The solar cycle
THE SOLAR CYCLE

  • Sunspot numbers increase and decrease

    • over an 11-year cycle

  • Observed for centuries.

  • Individual spots last from a few hours to months.

  • Studies show the Sun is in fact about

    • 0.1% brighter when solar activity is high.


Solar influences on climate
SOLAR INFLUENCES ON CLIMATE

  • Solar activity appears to slightly change the Sun’s brightness and affect climate on the Earth...


The maunder minimum
THE MAUNDER MINIMUM

  • An absence of sunspots was well observed

    • from 1645 to 1715.

  • The so-called “Maunder minimum” coincided with a cool climatic period in Europe and North America:

    • “Little Ice Age”

  • The Maunder Minimum was not unique.

  • Increased medieval activity

    • correlated with climate change.

MET 112 Global Climate Change



Orbital changes

Milankovitch theory:

Serbian astrophysicist in 1920’s who studied effects of solar radiation on the irregularity of ice ages

Variations in the Earth’s orbit

Changes in shape of the earth’s orbit around sun:

Eccentricity (100,000 years)

Wobbling of the earth’s axis of rotation:

Precession (22,000 years)

Changes in the tilt of earth’s axis:

Obliquity (41,000 years)

Orbital changes

MET 112 Global Climate Change


Met 112 global climate change lecture 4

Earth’s orbit: an ellipse

  • Perihelion: place in the orbit closest to the Sun

  • Aphelion: place in the orbit farthest from the Sun

MET 112 Global Climate Change


Met 112 global climate change lecture 4

Eccentricity: period ~ 100,000 years

MET 112 Global Climate Change


Met 112 global climate change lecture 4

Precession: period ~ 22,000 years

MET 112 Global Climate Change


Met 112 global climate change lecture 4

Axis tilt: period ~ 41,000 years

MET 112 Global Climate Change



Met 112 global climate change lecture 4

Temperature: the last 400,000 years

From the Vostok ice core (Antarctica)


Met 112 global climate change lecture 4

Fig 4.5

High summer sunshine, lower ice volume


Formation of glaciers
Formation of Glaciers

  • Glaciers - composed of fallen snow that is compressed into a large, thickened mass of ice over many years

  • Glacier Growth: When over a year snowfall (winter) is larger than snowmelt (summer)

  • Glacier Decay: When over a year snowfall (winter) is less than snowmelt (summer)

  • Glacier growth and decay largely influenced by summer temperatures.

MET 112 Global Climate Change


Internal forcing

____________________________

____________________________

Ocean changes

Chemical changes in the atmosphere (i.e. CO2)

Natural variations

Internal Forcing

Plate tectonics/mountain building

Volcanoes

MET 112 Global Climate Change


Activity
Activity

Consider the fact that today, the perihelion of the Earth’s orbit around the sun occurs in the Northern Hemisphere winter. In 11,000 years, the perihelion will occur during Northern Hemisphere summer. A) Explain how the climate (i.e. temperature of summer compared to temperature of winter) of the Northern Hemisphere would change in 11,000 years just due to the precession.

B) How would this affect the presence of Northern Hemisphere glaciers (growing or decaying)? Assume growth is largely controlled by summer temperature.

MET 112 Global Climate Change


If the earth s tilt was to decrease how would the summer temperature change at our latitude

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If the earth’s tilt was to decrease, how would the summer temperature change at our latitude

  • Warmer summer

  • Cooler summer

  • Summer would stay the same

  • Impossible to tell


A how would climate change

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A: How would climate change

  • Warmer winters, cooler summers

  • Warmer winters, warmer summers

  • Cooler winters, warmer summers

  • Cooler winter, cooler summer

MET 112 Global Climate Change


B how would glaciers change

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B: How would glaciers change?

  • Glaciers would grow

  • Glaciers would decay

  • Glaciers would stay about constant

MET 112 Global Climate Change