Climate Change

Geog 316.01 Fall 2006
SFSU
Climate
Change
Dr. B. Holzman
Climate Change
I. Climate Change
Direct Evidence
Historical data
Proxy data
II. Proxy data
Oceanic and Lake sediments
Pollen
Dendrochronology
Pack rats
III Climate changes over time
Past 100 years
Past 1000 years
Past 25,000 years
Past 150K years
Past million years
IV. Reasons for change (hypotheses)
Milankovich Cycle (orbit)
Axial tilt
Earth wobble
V. Summary
Evidence
Indirect / Proxy Records
Evidence
Direct/Historical
Pack rat (Neotoma sp.)
Packrat middens
Pack rat middens
Packrat middens
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
1
Geog 316.01 Fall 2006
SFSU
Dr. B. Holzman
Tree Rings
Palynology
Fire history
Tree growth
Bristle cone pine (Pinus longaeva)
Tree Rings
Increment corer
Ice cores
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
2
Geog 316.01 Fall 2006
SFSU
Orbital Cycles
Dr. B. Holzman
Milankovitch eccentricity cycle –
the earth's orbit around the sun is eliptical. (100,000
years)
• Orbit (eccentricity)
• Axial tilt
• Precession (Earth wobble)
Precession cycle 23,000 year cycle
Tilt cycle 41,000
Years 22.5-24.5
degrees
Changes in solar insolation over time
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
3
Geog 316.01 Fall 2006
SFSU
Dr. B. Holzman
Additional Factors:
Sunspots, Aerosols,
Volcanic Eruptions, Fires….
Greenhouse Effect
(increased methane,
carbon dioxide)
Suggests warming of
the planet (3+1.5C)
Probably much faster
than the past.
Rate of change could be
too rapid for plants, soils
to adjust.
Climate changes led to
other changes
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
4
Geog 316.01 Fall 2006
SFSU
Dr. B. Holzman
Global Warming
What will be the impact
of Global warming?
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
5
Geog 316.01 Fall 2006
SFSU
Risks from sea level rise, 2080. Source: R. Nicholls, Middlesex University in the
U.K. Meteorological Office. 1997. This picture shows the areas at risk of
flooding and numbers of people who will be affected if sea level rises by 44 cm.
Dr. B. Holzman
Tuvalu
Bangladesh
Maldives
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
6
Geog 316.01 Fall 2006
SFSU
Dr. B. Holzman
www.greenfacts.org/.../global-climatechange.htm
I.
Climate Change
A.
Direct Evidence/Historical data/
B.. Proxy data
Oceanic and Lake sediments
Pollen
Dendrochronology
Pack rats
II Climate changes over time
Past 100 years
Past 1000 years
Past 25,000 years
Past 150K years
Past million years
III. Reasons for change (hypotheses)
Milankovich Cycle (orbit)
Axial tilt
Earth wobble
IV. Change scenarios
V. Summary
For the exclusive use of students enrooled in Geog 316 at SFSU, Fall 2006
7