Greenhouse
Effect*
Two transparent
windows:
Solar radiation –
visible (0.3-0.8 mm)
 Earth radiation –
infrared (7-15 mm)

Major infrared absorbers:
CH4, Natural Gas
N2O, Nitrous Oxide
O3, Ozone
CO2, Carbon Dioxide
H2O, Water
CH4
N2O
O2,O3
CO2
H2O
* Piexoto & Oort
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IPCC – AR5 – Sept. 2013
Executive Summary
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2011 Mauna Loa CO2
Mauna Loa Monthly Mean CO2 in
parts per million (ppm).
August 2013: 395.15 ppm
August 2012: 392.41 ppm
National Oceanic and Atmospheric
Administration (NOAA)
http://www.esrl.noaa.gov/gmd/ccgg/t
rends/
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Last 1000 years of CO2
280 ppm
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400 ppm
Global Mean Surface Air Temperature to 2012
The graph shows global annual surface temperatures relative to 1951-1980
mean temperatures.
1.) The last decade was the hottest ever recorded.
2.) 2010 is the hottest year since records have been kept.
3.) The red line shows the 5-year average: Long-term trends are more
apparent. (Image credit: NASA/GISS)
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J. Hansen et al.,
Science 308,
1431, 2005.
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The Millennial Temperature Record
Jones, et al – Climatic Research Unit
http://www.cru.uea.ac.uk/cru/info/milltemp/
1683
Medieval Warm Period
Mini Ice Age

Proxies: Different choices of Northern Hemisphere proxies (trees, ice
cores, corals, lake & marine sediments, and historical documents)

Natural forcing from sun and volcanoes dominate the pre-1850 record
and only human activities appear to adequately explain the rise in
temperature during the 20th century.
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Global Mean Sea Level
Andrew: There’s unprecedented
flooding. Large parts of the
country are underwater. The
death toll is near half a million
and rising. And it’s not just
Bangladesh… There are people
out there saying this is the end.
Gabriel: The end of what?
Male, Maldives Capital
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Arctic Sea Ice AREA – September 29, 2013
Positive Feedback
from increased
absorption of solar
energy by black
water. Tipping point?
2007 IPCC projected
ice free summers by
mid-century
2012 projections now
as early as 2020
Open exploration for
natural resources.
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Greenland
Ice Melt
Extensive thinning of
margins (-1.5m/yr red,
+1.5m/yr blue)
Arctic Sea Ice Volume Anomaly:
May 31, 2011
Monthly anomaly relative to 1979-2010
Trend: -2.8 ± 1.0 in thousands of
km3/decade.
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Climate Change: An Impacts Summary




Open Arctic water in summer absorbs far more solar
energy than when ice-covered. [Positive feedback]
Sea Level Rise 1.) Melting ice sheets in Greenland,
Antarctica 2.) Expanding water volume
Snow pack in Rocky Mountains, Himalayan Mountains
 summer drought in downstream areas.
Thresholds, when crossed, make rapid transitions:
 Fresh water melting into the North Atlantic slows the Gulf
Stream
 Ocean surface temperature above 27oC  increased
hurricane severity.
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Observed GHG Emissions and Emission Scenarios
Each Emissions Scenario is a guess about our future carbon production
4.0-6.1°C
2.6-3.7°C
2.0-3.0°C
1.3-1.9°C
Peters et al. 2012a; Global Carbon Project 2012
http://www.globalcarbonproject.org/carbonbudget/index.htm
Geoengineering
Effectiveness
vs.
Affordability
Timeliness
[Fast/Slow]
Safety
[Low/Medium/High
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Geological Carbon Sequestration




John Rupp, Indiana Geological
Survey, Bloomington
Supercritical fluid above 70 bar
Indiana: ¼ GT/year CO2
Potential Indiana sites:
 Oil/natural gas formations
○ Secondary oil/gas recovery
○ Relatively small volumes
 Coal seams
○ Surface chemistry
○ Relatively small volumes
 Saline aquifers (25-60 GT)
○ Potentially large volumes
○ Pore size decrease with depth
○ High pressure fracture
○ Permeability vs. Porosity
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Feedback in Climate
[Or why we need models]
Positive feedback example:
T  T
A warmer surface
temperature reduces the size
of the highly reflective polar
ice fields. The less reflective
soil or open ocean absorbs
more solar radiation
increasing the surface
temperature even further.
Negative feedback example:
T
T
A warmer surface temperature evaporates
additional water forming more cloud. The cloud
layer reflects incoming solar energy, reducing the
surface temperature.
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 Climate
Models
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