Download "Climate Change: (aka Global Warming): Is it real or a hoax?"

Climate Change
(aka Global Warming)
Is it real or a hoax?
Is Al Gore or Michael Crichton right?
Dr. Bruce A. Wielicki
NASA Langley Research Center
VIMS Public Lecture Series
June 5, 2008
There are many ways
to view the Earth…..
With different stories to tell….
Where can I get good information?
• The three laws of solid climate change information:
IPCC, IPCC, IPCC.
• What is the IPCC?
– Intergovernmental Panel on Climate Change
– An international volunteer effort by 1000s of scientists:
climate, economics, technology
– Assess climate change every 5 to 6 years
– Evaluate the entire scientific journal literature (only peer
reviewed published journal results used)
– 3 reports (~ 1000 pages each)
• The Physical Science Basis (Working Group 1)
• Impacts, Adaptation, and Vulnerability (WG2)
• Mitigation (WG3)
– International science peer review by 1000s scientists
– Only the Policymaker Summaries (20 page) are debated
word for word with government reps (usually "softened")
What Should I be Skeptical Of?
• Any individual scientist: myself included.
– Will not have the depth to undertand the whole climate problem
– Vast majority of earth scientists endorse IPCC.
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Internet rants of any sorts (pro or con)
Internet articles from any individual (scientist or not)
Most Newspaper/TV/Radio media (untrained reporters)
Michael Crichton's "State of Fear": poor science
understanding (grade of "D" to "F")
• You CAN trust statements from major scientific
organizations (and they ALL endorse IPCC):
– National Academy of Sciences
– American Geophysical Union (~ 10,000 earth scientists)
– American Association for the Advancement of Science (~ 10
million scientists)
Climate System Energy Balance
Global surface temperature change 1850-2005
IPCC 2007
IPCC, 2007
Human Influence on Climate
Carbon Dioxide Trends: 100yr lifetime
Methane Trends
Sulfate Trends
Global Temperature Trends
From M. Prather University of California at Irvine
Human
Radiative
Forcing of
Earth's
Energy
Balance &
Climate
1750-2005
IPCC, 2007
How does the Earth Respond?
Forces Acting
On the Earth
System
Earth
System
Response
IMPACTS
Feedback
Of the total forcing of the climate system, 40% is due to the
direct effect of greenhouse gases and aerosols, and 60% is
from feedback effects, such as increasing concentrations of
water vapor as temperature rises.
What do physical climate models predict
the change should be?
Natural Forcings
Cannot Explain
Observations
IPCC, 2007
Natural Forcings: Solar, Volcanic Eruptions
Human Forcings: CO2, Methane, Aerosols, Ozone, Land change
Climate Model Predictions: Add Human Forcing
Natural Forcings
And
Human Forcings
Do Explain
Observations
IPCC, 2007
Natural Forcings: Solar, Volcanic Eruptions
Human Forcings: CO2, Methane, Aerosols, Ozone, Land change
What do climate models predict
regional change should be?
IPCC, 2007
Global Temperature Predictions
Uncertainty in climate sensitivity
Uncertainty in future emissions
IPCC, 2001
Global Temperature Predictions
IPCC, 2007
The Ice Ages: Temperature, Sea Level
Sea Level varies
by 100m (300ft)
from glacial to
Interglacial periods
Paleo data used to
estimate radiative
energy climate forcing
(doubled CO2 = 4 W/m2
Climate Model uses
paleo forcing to predict
temperature change
and compares well
to Paleo temperature
data.
Hansen, 2007
Common Climate Myth #1
Its just natural variability like glacial periods!
- glacial periods take 100,000 years: not 100
- glacial periods are forced by earths orbit around
the sun: its tilt (how strong the seasons are) and
the earths elliptical orbit (whether northern or
southern hemisphere is closer to the sun in summer
- these natural variations would take us to the next
ice age in 50,000 years or so.
- our CO2 fossil fuel emissions will equal the energy
forcing of the glacial cycle in the < 100 years: 1,000
times faster forcing of climate than glacial cycles but
of similar magnitude.
Fact: we are accidentally "geo-engineering"
our own planet.
Predicted Sea Level rise from 1990 to 2100
Uncertainty in climate sensitivity
Uncertainty in future emissions
IPCC, 2001
Climate Model Sea Level Predictions
Sea level rise continues for centuries:
Long after atmospheric temperature stabilizes
IPCC, 2001
Sea Level Rise of 4 meters = 12 ft, Peninsula
IPCC: 1 to 11ft ultimate sea level rise from ocean water thermal expansion,
depending on 2000-2100 emissions. Much larger rise if ice sheet losses:
caused 12 to 18 ft sea level rise when poles were warmer 125,000 years ago.
What about rainfall? Can Climate Models Predict It?
Winter: Dec/Jan/Feb
Summer: Jun/Jul/Aug
Obs
Models
3 mm/day = 3.5 inches per month = typical for Virginia
IPCC, 2007
What do climate models predict for
Rainfall Change From Current to 2090-2099
Wet gets wetter, Dry gets drier
Winter: Dec/Jan/Feb
Summer: Jun/Jul/Aug
IPCC, 2007
Change is given in percent of current rainfall climatology
Colored regions where at least 2/3 of climate models agreed
Stippled regions are where 90% of climate models agreed
Color shown is the average of all climate model predictions
What is Climate?
• Climate is the long term average of weather.
– 14-day weather prediction limit:
but no known limit to climate
prediction.
– Weather data accuracy is 1 degree,
but climate accuracy is 0.1 degree:
a factor of 10 tougher measurement.
Common Climate Myth #2
We can't predict weather 5 days from now!
How can possibly predict climate 100 years out?
- Weather is driven by dynamics: inherently chaotic
- Climate is driven by energetics: more constrainted physics
- YOU already know how to predict climate 6 months out
better than the weatherman can predict 5 days out
- How different is the Gloucester average summer daytime high
than the winter daytime high? This climate difference is driven
by energetics: more sun in the summer than winter.
Fact: climate is inherently more predictable than
weather. The longer the time average the more
predictable it becomes (month, year, decade)
What is a computer model
of the climate system?
Major Climate System Elements
Carbon Cycle
Atmospheric Chemistry
Water & Energy Cycle
Coupled
Chaotic
Nonlinear
Atmosphere and Ocean
Dynamics
How do we use observations to
test and improve climate models?
NASA Has Engaged in Earth Science
From the Very Beginning
TIROS IX mosaic, February 13, 1965
Earth View From MODIS on the Terra Spacecraft 2001
Vegetation from MODIS on Terra
Summer, 2001
Carbon
Monoxide
MOPPITT
On Terra
April &
October
2000
Unprecedented Accuracy of new EOS Radiation Data
What are the IPCC Conclusions?
•
"Global atmospheric concentrations of carbon dioxide, methane,
and nitrous oxide have increased markedly as a result of human
activities since 1750 and now far exceed pre-industrial values
determined from ice cores spanning many 1000s of years"
•
"Warming of the climate system is unequivocal (>99% certain) and
is now evident from observations of increases in global average
air and ocean temperatures, widespread melting of snow and ice,
and rising global mean sea level."
"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 sea level
rise" (I.e. 12 to 18 ft).
"Most of the observed increase in globally averaged temperatures
since the mid-20th century is very likely (>90% certainty) due to
the observed increase in anthropogenic greenhouse gas
concentrations"
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"Anthropogenic warming and sea level rise would continue for
centuries due to the timescales associated with climate processes
and feedbacks"
IPCC Policymakers Summary: The Physical Science Basis, Feb 2007
What can we do about it?
•
Buy more fuel efficient cars. Go from 18mpg (e.g. suv) to 50mpg
(e.g. prius). This will also spur future even more efficient cars.
•
Change from incandescent light bulbs to compact floursescents
(they use 1/3 to 1/4 the electricity and therefore carbon dioxide).
These payback in months to a year at most.
When you change refrigerators, air conditioning compressors,
heat pumps, gas furnaces: buy the most energy efficient ones that
can pay you back in 10 years or less. No net cost, but does
require planning.
Have an energy audit of your house to see where you could save
energy and still be paid back in 5 to 10 years.
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Most in U.S. could cut energy use 50% through efficiency
Average U.S. household emits 50,000 lbs of CO2 per year
– 1 gallon of gasoline emits ~ 20 lb of CO2
– 1 Kilowatt-Hr of electricity (~ 10 cents) emits ~ 2 lb of CO2
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Stabilizing CO2 requires ~ 60 to 80% reduction in fossil fuel use
Develop and use renewable energy (wind, solar)
•
Ethanol currently uses as much CO2 as it saves
What can we do about it?
•
Develop carbon storage methods (e.g. pump into ground)
•
Narrow the uncertainties (factor of 3) by improving climate science
– Still have no designed climate observing system
– Still have no climate agency (job is ~ size of NASA)
– Have a weak collection of 12 agencies all of whom have different
missions with higher priority: climate science is lost in the cracks.
– Amount of warming by 2100 is still uncertain to factor of 3:
2C to 6C (4F to 11F)
– Amount of sea level rise by 2100 could be 1ft to greater than 4ft.
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Are we capable as a society of global action with 10 to 50 year
planning?
– Start early on carbon cap & trade or carbon taxes and then every 5 to 10
years review progress of economics, renewable energy technologies,
and accuracy of climate science predictions: then adjust the strategy.
– Don’t wait until everyone in the world agrees: it will be too late.
– IPCC economics reports estimate only 1% of global GDP total cost to
solve over the next 50 years: but only if we start now.
“Nature is a mutable cloud which is always
and never the same”.
- Ralph Waldo Emerson (1803-1882)
“Man masters nature not by force,
but by understanding.”
- Jacob Bronowski, 1956