MET 112 Global Climate Change Lecture 10 - PowerPoint PPT Presentation

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MET 112 Global Climate Change Lecture 10

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GISP2 ice core (Greenland Summit) Archived at the National Ice Core Laboratory in CO. ... Melting of Greenland Icesheet. Global rise in sea level last 20,000 years ... – PowerPoint PPT presentation

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Title: MET 112 Global Climate Change Lecture 10


1
MET 112 Global Climate Change Lecture 10
  • Observations of
  • Recent Climate Change
  • Dr. Craig Clements
  • San Jose State University
  • Outline
  • How do we observe?
  • Recent trends in temperature
  • Recent trends in GHGs

2
What does to observe mean?
- to watch and record.
Where do our observations come from?
  • Measurements
  • Of what?
  • Who compiles these measurements for governments
    and society?
  • IPCC
  • Intergovernmental Panel on Climate Change
  • www.ipcc.ch

3
Temperature stations
4
Change in surface temperature in 20th century
5
Bubbles Trapped in ice core
Petit, Jean-Robert, et al (1999). Climate and
atmospheric history of the past 420,000 years
from the Vostok ice core, Antarctica. Nature
399 429-436.
6
Ice Core layers
  • GISP2 ice core (Greenland Summit)
  • Archived at the National Ice Core Laboratory in
    CO.
  • from 1837-1838 meters in which annual layers are
    clearly visible.
  • The appearance of layers results from differences
    in the size of snow crystals deposited in winter
    versus summer
  • Counting such layers has been used (in
    combination with other techniques) to reliably
    determine the age of the ice.
  • This ice was formed 16250 years ago during the
    final stages of the last ice age and
    approximately 38 years are represented here.

7
Ice Cores
8
Coring Earths ice sheets
9
Coring mountain glaciers
10
Ice core record
11
Ice core CO2 record
12
Retreat of mountain glaciers visual inspection
Boulder Glacier, Mt. Baker, Washington
13
Retreat of mountain glaciers
14
Melting of Greenland Icesheet
15
Global rise in sea level last 20,000 years
16
Global rise in sea level in the 20th century
17
Shorter winters in Alaska
18
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19
Latest global temperatures
20
Current CO2 383 ppm
21
What Changed Around 1800?
  • Industrial Revolution
  • Increased burning of fossil fuels
  • Also, extensive changes in land use began
  • the clearing and removal of forests

22
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23
Burning of Fossil Fuels
  • Fossil Fuels Fuels obtained from the earth are
    part of the buried organic carbon reservoir
  • Examples Coal, petroleum products, natural gas
  • The burning of fossil fuels is essentially
  • A large acceleration of the oxidation of buried
    organic carbon

24
Land-Use Changes
  • Deforestation
  • The intentional clearing of forests for farmland
    and habitation
  • This process is essentially an acceleration of
    one part of the short-term carbon cycle
  • the decay of dead vegetation
  • Also causes change in surface albedo (generally
    cooling)

25
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26
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27
Greenhouse Gases
  • Carbon Dioxide
  • Methane
  • Nitrous Oxide
  • CFCs (Chlorofluorocarbons)
  • Others

28
Methane
29
Anthropogenic Methane Sources
  • Leakage from natural gas pipelines and coal mines
  • Emissions from cattle
  • Emissions from rice paddies

30
Nitrous Oxide N2O
31
Anthropogenic Sources of Nitrous Oxide
  • Agriculture
  • Bacteria in Soils
  • Nitrogen fertilizers

32
CFCs (Chlorofluorocarbons)
CFC-11
CFC-12
33
Sources of CFCs
  • Leakage from old air conditioners and
    refrigerators
  • Production of CFCs was banned in 1987 because of
    stratospheric ozone destruction
  • CFC concentrations appear to now be decreasing
  • There are no natural sources of CFCs

34
Latest global temperatures
35
The Land and Oceans have both warmed
36
Precipitation patterns have changed
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