Why Climates Change
Dr. Mary Snow and Dr. Rich Snow
Applied Aviation Sciences
Embry-Riddle Aeronautical University
Daytona Beach, Florida
Geologic Time Scale
Divides Earth’s 4.6 billion-year History into:
Eons, Eras, Periods, and Epochs
If a 24-hour day represents all of history,
humans arrived during the last minute
To understand climate change,
we need to understand what
causes a place on Earth to have
a certain climate in the first place
What are the largescale climate controls?
Climate Controls:
1) Latitude
2) Altitude
3) Currents
4) Land and Water Differences
5) Continental Drift
6) Astronomical
7) Composition
Let’s Take a Brief Look at Each...
1) Latitude
Earth’s Axis Points North, so During the Year
Different Latitudes Receive the Direct Rays of the Sun.
Summer
(in the Northern Hemisphere)
Winter
(in the Northern Hemisphere)
2) Altitude
Atmosphere is Warmed from Below by Earth
Higher Altitudes are Colder
3) Currents
Large Scale Gyres in the Oceans
Continually Redistribute Heat Energy Poleward
Global Winds
Also Transport Heat Energy Around Earth
4) Land & Water Differences
Water heats and cools far more slowly than does land
5) Continental Drift
Earth’s crust is fractured into
plates that move in various directions…
6) Also Consider
Astronomical
Forcing Mechanisms…
Milankovitch Cycles
Occur every 100,000 years---Often it is these cycles that are referred to as
CYCLICAL CLIMATE CHANGE
However, the IPCC and other climate scientists
compare CURRENT TRENDS to this
NATURAL RANGE OF VARIABILITY.
Temperatures Over Past 2 Million Years
100,000-Year Pattern of Glacial & Interglacial Periods:
90,000 Years of Cooling & Expanding Ice Sheets
10,000 Years of Warming & Rising Sea Levels
7) Composition
Earth’s climate evolved VERY slowly
over its 4.6 billion year history
The relatively recent change,
especially in the addition of
greenhouse gases (GHGs)
FROM BURNING FOSSIL FUELS,
has been VERY rapid.
Data from direct observation
What is global warming?
Shortwave radiation from Sun
passes through the atmosphere
and is absorbed by Earth’s surface.
Absorption changes the surface
and the wavelength.
Earth re-radiates
longwave radiation that
is absorbed by greenhouse gases
(GHGs) and warms the atmosphere.
What are the primary GHGs and their sources?
Sources
GHGs
What evidence do we have of a warming atmosphere?
Insight into past climates is based on
both proxy data and direct observation.
Dendroclimatology
Tree rings provide
records of
previous climates.
Lake bottom sediment cores trap pollen grains
Pollen diagrams provide information of
past vegetation, and therefore, climate, at a site.
Proxy data are also
provided by
core samples taken
by drilling through…
coral beds,
river beds,
and seafloors.
Variations of Earth’s surface temperature
for the past 1,000 years
Proxy data from ice core drilling:
Antarctica’s Vostok Station
Drilling Station
Air bubbles trapped in ice are tiny packages or samples
of atmospheric composition through time.
National Ice Core Laboratory
University of New Hampshire
Library of Paleoclimate
Data from direct observation
Variations of Earth’s surface temperature
for the past 140 years
Earth’s mean surface temperature has increased
about 1.2º F to 1.5º F since 1900.
(NOAA, 2005)
NASA reports that most of the warming
has occurred over the past 30 years.
(NASA, 2005)
Greenhouse gases from fossil fuel combustion are responsible
for most of the warming of the last 50 years.
(EPA, 2006)
In the U.S.,
2006 was the warmest year
on record.
Globally,
2005 was the warmest year
on record.
Of the twelve
warmest years on record,
eleven occurred
during the past twelve years
(1995-2006).
(IPCC, 2007)
Climate models predict that mean Earth
temperature could increase from 2.5ºF
to 10.4ºF above 1990 levels by 2100.
“Global temperatures are dangerously close
to the highest ever estimated to have
occurred in the past one million years”
(NASA, 2006).
What evidence is there beyond CO2 and temperature data?
The Snows of Kilimanjaro
1993
2000
A Peruvian Glacier
1978
2000
Argentina's Upsala Glacier
Rhone Glacier in Switzerland
1906
2003
Antarctica’s ice sheet lost approximately 150 cubic kilometers of ice
annually between 2002-2005 (1 cubic km = 260 billion gallons of water)
(NASA, 2006)
What are other potential impacts of climate change?
Loss of Biodiversity
(species extinction is 1000 times
the background rate)
 Health Risks
 Increased Energy Usage
 Shifting Agricultural Patterns
 Diminished Water Resources
More Extreme Weather Events
 Thermohaline Circulation Disruption
 Rising Sea Levels
What multi-media tools do we have?
Climate Change Cinema
Why does there still seem to be a
global warming debate?
In 1988, the World Meteorological Organization (WMO) and
the United Nations Environment Program (UNEP) established
the Intergovernmental Panel on Climate Change (IPCC) which is
comprised of ~2,500 of the world’s best atmospheric scientists.
The role of the IPCC is to
“understand climate change, its impacts,
and options for adaptation and mitigation.”
The Response from Business and Industry…
Global Climate Coalition
Founded in 1989 by 46 corporations representing a
"voice for business in the global warming debate."
Greening Earth Society
Founded in 1998 by the Western Fuels Association
to promote the view that increasing levels of
atmospheric carbon dioxide are good for humanity.
Key players in a well-funded misinformation campaign
Designed to frame climate scientists as “alarmists”
And climate change as a “theory” fraught with “uncertainty”
George Marshall Institute and
the Oregon Institute of Science and Medicine
“The Petition Project” designed to undermine
and discredit the scientific authority of the IPCC.
Petition was sent to 1000s of scientists with an
article formatted to mimic the journal of the
National Academy of Sciences.
The NAS released a strong statement
disclaiming any connection to this effort
and reaffirming the reality of climate change.
“In my more than three decades in the government
I've never witnessed such restrictions
on the ability of scientists
to communicate with the public.”
“Politicians are rewriting the science.”
James Hansen, NASA Goddard
A survey of federal scientists reveals that 46 percent
felt pressure to eliminate the words “climate change,”
“global warming” or similar terms from
communications about their work.
What Can We Do?
Replace incandescent bulbs
with compact fluorescent light bulbs
Move your thermostat down in winter and up in summer
Clean or replace filters on your furnace and air conditioner
Wrap your water heater in an insulation blanket
Weather-strip windows and doors
Use less hot water
Turn off and unplug electronic devices you’re not using
Reduce, reuse, and recycle
Plant trees
Buy local products
Eat less meat
Try walking, biking, carpooling or mass transit when possible
Encourage your school or business to reduce emissions
Encourage development of renewable energy
Protect and conserve forests worldwide
Tell politicians to act
Vote --- for candidates who are interested
in mitigating climate change!
Educate and Inspire!
www.climatecrisis.net