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The Scientific Basis of Global Climate Change

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The Scientific Basis of Global Climate Change Dr. Jim Phillips, UWEC Chemistry For ECON 286: 3/29/13 – PowerPoint PPT presentation

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Title: The Scientific Basis of Global Climate Change


1
The Scientific Basis of Global Climate Change
  • Dr. Jim Phillips, UWEC Chemistry
  • For ECON 286 3/29/13

2
Final exam question for CHEM 127
Concisely re-state the scientific argument that
supports the following hypothesis   Human
activity has led to global warming   Present
this case in a systematic, logical manner. I am
looking for three specific points (BTW
course is offered ON LINE this summer!!!)
3
History Lesson First !
Svante Arrhenius Global Warming
Hypothesis (Philosophical Magazine -
1896) Increased Levels of CO2 and other
greenhouse gases will lead to an increase in
global temperature Other GHGs include H2O,
CH4, N2O, and Halocarbons . (Stay tuned)
4
1 Average Global Temperature is Increasing
5
Other evidence? Sea level up - snow ice
melting
IPCC, AR4, WG1, 2007
NOAA, CMDL, 2009
6
2 CO2 (and other GHGs) are increasing!
C.D. Keeling and T.P. Whorf (October 2004).
7
Do human CO2 sources rival nature ? (i.e. How
is that possible? the planet is so big or you
cant tell me that my car is causing this
Natural CO2 emissions Terrestrial Biosphere
60.0 Pg/year Marine Biosphere 90.0 Pg/year
Anthropogenic CO2 emissions Fossil Fuels 6.0
Pg/yr (1.5 US!) Deforestation 1.5 Pg/yr
8
Greenhouse gas concentrations the last 10,000
years
gt CO2 - 35 increase
gt CH4 - more than 2x!
gt N2O - 20 increase
Halocarbons gt 8 increase
9
How do we know ? The Vostock Ice Core
BUT DOES THIS PROOVE ANYTHING?
Nature v. 412, p. 523-527 (2 August 2001)
10
Lets Back up 3 fundamental factors that
influence climate
http//earthobservatory.nasa.gov/Features/CALIPSO/
CALIPSO2.php
11
3 Main Climate Influences means gt 3
possibilities for warming (or cooling?) 1)
Incoming Solar Radiation - Sun itself, or
orbital variations 2) Reflectivity (Albedo)
- Surface (land use), clouds, Aerosols 3)
Greenhouse effect - H2O, CO2, CH4, N2O or
Halocarbons Human activities have altered
these 2
12
1) Incoming Solar Radiation - Sun itself, or
orbital variations
13
2) Reflectivity (Albedo) - Surface (land
use), clouds, Aerosols
14
3 Main Climate Influences means gt 3
possibilities for warming (or cooling?) 1)
Incoming Solar Radiation - Sun itself, or
orbital variations 2) Reflectivity (Albedo)
- Surface (land use), clouds, Aerosols 3)
Greenhouse effect - H2O, CO2, CH4, N2O or
Halocarbons Human activities have altered
these 2
15
Why things are not so simple Feedbacks gt not
only are there other factors they
interact Consider this example Increased
Global T gt more H2O vapor
  • Enhanced Greenhouse gt Increased T !
  • A positive feedback gt Unstable Climate

2) More clouds gt more reflected Radiation gt
Decreased T A negative feedback gt Stable
Climate
16
Considerations (now back to science)
What is Scientific Proof? What
Experiment can we do? Where IS the burden of
proof ? (i.e., should the scientists that
believe climate change is real have to bear
this ?)
17
Figure Courtesy of IPCC
18
Scientific Agencies that support work of
IPCC American Chemical Society
http//portal.acs.org/portal/PublicWebSite/policy
/publicpolicies/promote/globalclimatechange/WPCP_0
11538 American Geophysical Union http//www.agu
.org/sci_pol/positions/climate_change2008.shtml
National Academy of Sciences http//www.nasonli
ne.org/programs/sackler-colloquia/2011-sackler-lec
ture.html The list goes on
19
How do we know? Models can reproduce Global T
trends - ONLY if human effects are included.
lt Global Temperature as modeled WITH
Anthropogenic Factors
lt Global Temperature as modeled WITHOUT
Anthropogenic Factors
20
Models Observations Causes
  • Key Points
  • 1) The planet IS getting warmer
  • 2) CO2 and other GHGs are by far the dominant
    factor
  • 3) No existing model can reproduce the recent
    global temperature trends using strictly natural
    factors
  • This is how we know

21
2007 IPCC report - Future T predictions
Key Points  ALL model scenarios predict
warming Range 2-4C (3-7F) (except
constant composition) Our choices
matter Climate stability is assumed by default
- instability may arise at gt 450 ppm CO2 ?!?!?!
22
AcknowledgmentsThanks for Inviting me Dr.
J!!!(thank you for your time and attention)
  • QUESTIONS?
  • COMMENTS ?

23
Future Global Impacts (beyond sea level)
24
Here in Wisconsin (WI DNR)
  • wetter winters and drier summers with longer,
    hotter and more frequent heat waves
  • weather could require farmers to raise different
    crops
  • dairy cattle beleaguered by heat exhaustion
    and growing pest populations
  • poorer air quality
  • warmer and more shallow river waters could hurt
    populations of cold-water fish like trout
  • denser algae blooms and lower oxygen levels in
    ponds and lakes
  • more frequent floods, droughts, forest fires and
    damaging storms
  • changes in tree species that could affect the
    forestry industry and wildlife populations
  • increases in disease-carrying insect populations

25
What can we do ?
  • (personal)
  •   Hold leaders accountable for change
  • Conserve energy (at home, drive less, buy less,
    eat less)
  • Recycle
  • (state/local)
  • Demand cleaner energy/greater efficiency from
    utility co.
  • Land Use reduce urban sprawl, create
    pedestrian/bicycle friendly communities
  • (national/global)
  • Get the US back at the negotiation table
  • Stabilize Global population (empower women)
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