Climate Change, Peak Oil, and the

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Climate Change, Peak Oil, and the End of the
World (as we know it)
Richard Sedlock SJSU Geology
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What is climate?
How does climate differ from weather?
TIME
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What Factors Affect Climate?
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More factors that control climate.
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Mountains (rain shadows) affect precipitation
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1. Where are the warmest and coolest areas on
Earth?
Where are the warmest and coolest places along
60N?
What is ?T?
28 F
4. What might account for these differences?
Continent vs. ocean
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And yet more natural forcings of climate on
Earth Internal forcings atmosphere
composition and circulation oceans
temperature, salinity, and circulation
mountains volcanic eruptions External
forcings solar variability orbital
variations impacts (e.g., Chicxulub at the K-T
boundary)
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It starts with the Sun.
Insolation
Incoming solar radiation
44 infrared or longer 48 visible wavelengths
7 UV or shorter
Earth radiates 100 infrared
For a blackbody (perfect absorber
emitter) Insolation outgoing radiation
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If Earth was a perfect blackbody, equilibrium
surface T would be 18C (255 K) 0 F
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But the average temperature of Earths surface is
about 15 C (278 K) 59 F. Why??
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The Greenhouse Effect
1. Insolation absorbed by Earths surface.
2. Earth emits infrared radiation.
3. Greenhouse gases absorb some of Earths
infrared radiation.
4. Greenhouse gases emit infrared radiation in
all directions.
5. Earth absorbs downward-directed infrared
radiation.
Result Warmer surface temperature
The greenhouse effect is misnamed a real
greenhouse works because inside air is physically
separated from outside air.
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Headlines
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Observations
Rising temperature Rising sea level
Decreasing snow cover
2000
1950
1900
1850
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Rapid increase in the level of atmospheric CO2
see Ahrens/Miller Fig. 1.4, p. 6
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Retreat of most mountain glaciers
This graph shows changes in the length of
glaciers relative to 1950 (set 0).
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Do these phenomena indicate that climate is
changing?
In other words What is the natural variability
of climate?
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Lowery Glacier
Robb Glacier
Antarctica
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Evidence of past glaciers
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Based on these and many other features,
geologists have mapped out the locations of
glaciers and ice sheets in the past.
See workshop Web site for this animation.
So climate clearly does change naturally.
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Ice cores from the last 650,000 years
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Check out other greenhouse gases. Nitrous oxide
(N2O) is used in fertilizers, aerosols, engines,
and anesthetics it was first synthesized in 1775.
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Methane (CH4) is part of natural gas (the fossil
fuel). It also results from fermentation
of organic matter
wetlands rice fields landfills livestock
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Human activities that have influenced climate
Burning fossil fuels (since the Industrial
Revolution)
Tropospheric ozone
Increased levels of atmospheric GHGs
Agriculture fertilizers rice
Earths albedo
Livestock
Deforestation
Aerosols
Modern technology
Stratospheric ozone
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IPCC 4th report (2007) Since 1750, it is
extremely likely gt95 that humans have exerted
a substantial warming influence on climate.
Anthropogenic
IPCC Intergovernmental Panel on Climate Change
Natural
Total anthropogenic
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Whats in a name? Global Warming vs. Climate
Change
Though global warming permeates media
coverage, climate change is scientifically more
accurate (contrarians prefer it because it sounds
less problematic).
Climate involves more than temperature
precipitation amount, timing, and
distribution cloud type and distribution wind
pattern and speed frequency of extreme weather
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How do we predict the climate of the future?
We use climate modelsmathematical
representations of the physical processes and
components of Earths climate system to infer
the climate systems features, variability, and
response to changes.
This is an immense design computation
challenge the models run of some of the worlds
largest supercomputers.
The models do a pretty good job of simulating
recent climate, and are getting better at it.
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To test the models, we ask them to simulate
recent climate, then compare them to each other
and to direct observations weve made.
Results of 58 simulations produced by 14
different global climate models (1) Differences
are minor. (2) The model average outperforms
individual models, and does a nice (but not
perfect) job of simulating recent climate.
Thus, the models have a reasonable probability of
predicting future climate.
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What can we infer from model studies of global
surface T?
2. Natural factors were the chief influence on T
from 1900 to 1950.
3. Humans were the chief influence on T from 1950
to 2000.
6. Climate models can predict 20th-century T only
by using both natural and anthopogenic
factors.
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Feedbacks Bugaboo of climate models
Negative ( ) feedbacks return components of a
system towards their original states after a
small disturbance, and thus act as stabilizers.
Stability is most likely when the negative
feedback acts rapidly and gently.
Positive ( ) feedbacks add to or amplify a
disturbance of the original state.
2. Number of humans on Earth
3. Number of deer in Arkansas
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Climate forcings are perturbations that produce
negative or positive feedbacks throughout the
climate system.
Example Icealbedo feedback
albedo reflectivity
positive
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Now lets consider feedbacks involving clouds.
increases
increases
increases
increases
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Unstable? Tipping Points?
Current models predict stable global climates.
However, as the models incorporate more
components, the range of possible feedbacks will
increase, and the models will predict more
complex, possibly chaotic, climate behavior.
Climatologists recognize that Earths climate
system (or part of the system) may become so
disturbed (i.e., it crosses some threshold value
or state) that predictable, stable behavior does
not happen. tipping points.
Current models would not be applicable, and much
larger (or smaller?) changes may occur.
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The 4th IPCC report lists 54 key uncertainties.
Better models require resolution of these. Here
are a few
The dynamics of melting ice sheets The rate of
sea-level rise could be 1020 (or more?) higher
if the thinning or removal of ice shelves
accelerates the downhill flow of glaciers.
Drop in CO2 uptake rate All models indicate
positive feedback between rising temperatures and
lowered rates of land and ocean uptake of CO2,
but estimates of the strength of the feedback
vary greatly.
Projected CH4 concentrations Models project
increasing methane, but are uncertain of the size
of the increase (trouble modeling permafrost,
wetlands methane clathrates other sources).
The feedback between warming and aerosols
Warming is thought to result in decreased aerosol
production, but the effects of changing
precipitation and biospheric adaptations are very
uncertain.
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Global warming projections for the 21st century
C
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Projected T increase, 2071-2100
Greatest warming continents high latitudes
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Projected annual change in precipitation
Wetter high latitudes, drier subtropical latitudes
2071-2100
Model A2

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Projected changes in soil moisture
Drier soils trouble for agriculture
Model A1B, 20802099
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Heat waves
5 or more consecutive days w/max T gt5 C above
climatic average
Model A1B, 20802099
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Numbers of marine organisms would plummet, and
the oceans food chain may collapse.
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This animation shows the minimum extent of sea
ice in the Arctic (early September), 1979-2005
See workshop Web site for this animation.
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Projected warming of atmosphere (top) and ocean
(bottom)
20112030
20462065
20802099
Model A1B
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How well do models predict modern precipitation
rates?
Top row current observations
Dec/Jan/Feb
Jun/Jul/Aug
Bottom row model average
A very good (but not perfect) simulation
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Projected annual change in precipitation
2090-2099
Model A1B
Dec to Feb
White lt60 of models agree on sign ( / -) of
the change
Stipple gt90 of models agree on sign ( / -) of
the change
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Projected rise in sea level
Note the large uncertainties. Causes of
sea-level change are poorly understood.
Does not include catastrophic failure, tipping
points, or chaotic behavior
GEOL 4L Web site animations
uncertainties
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Lots of bad news, but
Its not hopeless!!
Human ingenuity and technology are remarkable.
Appropriate policy choices are available
to minimize and adapt to climate change.
Maybe well be lucky, and unanticipated factors
or feedbacks may slow the rate of change.
Perhaps we (esp. U.S.) will be forced to change
by the price and availability of fossil fuels.