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Global Warming Briefing for
KSL Television
Lis Cohen
University of Utah
[email protected]
www.WeatherOutreach.org
Today’s Topics
• Temperature Trends
• What is Global Warming?
– Causes
– Uncertainties
• Consequences of Global Warming
• What can people do about this problem?
Data Sources
• The 2007 IPCC (Intergovernmental Panel on Climate
Change) report
– Includes
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2,500 + scientific expert reviewers
800+ contributing authors
450+ lead authors from
130+ different countries
6 years of work
4 volumes
1 report
• Scientific Literature
• Presentations from experts at the University of Utah –
Dr. Dave Chapman, Dr. Tim Garrett, Dr. Gerald Mace,
Dr. Thomas Reichler
Temperature Analysis
• “Warming of the climate system is
unequivocal, as is now evident from
observations of increases in global
average air and ocean temperatures,
widespread melting of snow and ice,
and rising global average sea level”
(IPCC report 2007).
Contributions to Sea Level Rise
Long-term Changes in Climate
• Long-term changes are observed at:
– Continental Scales
– Regional Scales
– Ocean basin Scales
• These changes include:
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Changes in Arctic temperatures and ice
Widespread changes in precipitation amounts
Ocean salinity
Wind patterns
Aspects of extreme weather
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including droughts
heavy precipitation
heat waves
intensity of tropical cyclones
- 2007 IPCC report
What can influence the climate?
• Changes in these factors alter the energy
balance of the climate system:
– The atmospheric abundance of greenhouse
gases and aerosols
– Solar radiation
– In land surface properties
-2007 IPCC Report
The Greenhouse Effect
Effects of changing the amounts of
Greenhouse Gases
• These changes are expressed in terms of
radiative forcing, which is used to compare
how a range of human and natural factors
drive warming or cooling influences on
global climate.
LOSU = level of understanding
RF = Radiative Forcing
Error bars
Additional forcing factors not included here are considered to have a very low
level of scientific understand.
How is the sun affecting climate
change?
The effect of the sun’s variations
accounts for +.12 W/m2.
There is very high confidence that
the globally averaged net effect of
human activities since 1750 has
been one of warming, with a
radiative forcing of +1.6
[+0.6 to +2.4] W/m2.
Natural Climate Variability because
of the sun has been not very
significant.
How do we know that this is
not a normal cycle?
We use past climate data and
compare influencing factors.
How do we know about past
climates?
• Tree Rings – Growth is controlled by temperature,
precipitation and sunlight
• Pollens – give a good indication of what was living at the
time indicating a temperature range
• Ice and sea bed cores – Gasses in bubbles, dust,
isotopes, accumulation rate
• The fossil record
• Coral beds
Note: Uncertainties generally increase with time into the
past due to increasingly limited spatial coverage.
Paleoclimate Information
“Paleoclimate information supports the
interpretation that the warmth of the last half
century is unusual in at least the previous
1300 years.”
“The last time the polar regions were significantly
warmer than present for an extended period (about
125,000 years ago), reductions in polar ice volume
led to 4 to 6 meters (13-20 feet) of sea level rise.”
-2007 IPCC Report
What has Changed and what
has Not Changed?
Aspects of climate that have NOT changed
• Day night temperature differences have remained
constant. Both the maximum and minimum
temperatures have increased at the same rate. The
trends are highly variable from one region to another.
• Antarctic sea ice extent continues to show inter-annual
variability and localized changes but no statistically
significant average trends, consistent with the lack of
warming reflected in atmospheric temperatures
averaged across the region.
• There is insufficient evidence to determine whether
trends exist in
– Meridional overturning circulation of the global ocean
– Small scale phenomena
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Tornadoes
Hail
Lightning
Dust-storms
Consequences of
Global Warming
Ward Hunt Ice Shelf, 2002
Trend of Less Ice
• Many ice bodies
from the poles to
the tropics are in
retreat.
• Polar warming in
2100 may reach
levels of 130,000
years ago, when
sea levels were
several meters
above today.
Larsen B ice shelf, Antarctica
ca. 100 x 80 miles
Feb. 17, 2002
Mar. 5, 2002
Muir Inlet, Alaska
1941
Glacier Bay National
Park and Preserve
2004
National Snow and Ice data center
http://nsidc.org/cgi-bin/gpd_run_pairs.pl
Arctic Polar Ice Cap
1979
2003
http://www.nasa.gov/centers/goddard/news/topstory/2003/1023esuice.html
• Since 1979, the size of the summer
polar ice cap has shrunk more
than 20 percent.
• On Sept. 21, 2005, sea ice extent dropped to 2.05 million sq. miles,
the lowest extent yet recorded in the satellite record.
• This loss is twice the size of Texas.
NASA
Global Warming
1. Warming is real.
2. Humans are contributing to
the warming.
3. Feedback system is complex.
4. Greenhouse gas emissions are
growing; residence times are
long.
5. Consequences of warming
will not be easy for human
life.
How can everyone help?
Vote for politicians that strongly support
the environment!
Other ideas…
Carpool When You Can
Reduce Garbage
Plant a Tree
Insulate Your Water Heater
Replace Old Appliances
Weatherize Your Home
Use a Push Mower
Unplug Un-Used Electronics
Put on a Sweater
Insulate Your Home
Air Dry Your Clothes
Switch to a Tankless Water Heater
Switch to Double Pane Windows
Buy Organic Food
Bring Cloth Bags to the Market
Use Compact Fluorescent Bulbs
Inflate Your Tires
Change Your Air Filter
Fill the Dishwasher
Use Recycled Paper
Adjust Your Thermostat
Check Your Water heater
Change the AC Filter
Take Shorter Showers
Install a Low-Flow Showerhead
Buy Products Locally
Buy Energy Certificates
Buy Minimally Packaged Goods
Buy a Hybrid Car
What you at KSL can do!
• Talk to your viewers about climate change and let them
know what they can do to help!
– There are many events in Salt Lake about climate change (you
can cover them).
– Talk with politicians who have worked on the issue.
– Interview scientists at the University of Utah (I can help you with
this).
• Get the ball rolling and see what questions and concerns
your viewers have and answer them.
• Try to get rid of their misconceptions about climate
change.
• Talk to your viewers about climate change (Repeated for
emphasis )!
References
• Climate Change 2007: The Physical
Science Basis. Intergovernmental Panel
on Climate Change.
• Garrett, T. “Rapid Arctic Climate Change
Forcing the Feedbacks.” 2007.
• Chapman, D. “Global Warming – Just Hot
Air?” 2006.
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Thank you!
Questions?
Lis Cohen:
[email protected]