Greenhouse Effect*

Two transparent windows:

Solar radiation – visible (0.3-0.8 m m)

Earth radiation – infrared (7-15 m m)

Major infrared absorbers:- CH4, Natural Gas- N2O, Nitrous Oxide- O3, Ozone- CO2, Carbon Dioxide- H2O, Water

* Piexoto & Oort

CH4

N2O

O2,O3

CO2

H2O

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IPCC – AR5 – Sept. 2013Executive Summary

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2011 Mauna Loa CO2Mauna 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/trends/

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Last 1000 years of CO2400 ppm

280 ppm

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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.

The Millennial Temperature RecordJones, et al – Climatic Research Unithttp://www.cru.uea.ac.uk/cru/info/milltemp/

Proxies: Different choices of Northern Hemisphere proxies (trees, ice cores, corals, lake & marine sediments, and historical documents)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.

1683Medieval Warm Period

Mini Ice Age

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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-century2012 projections now as early as 2020

Open exploration for natural resources.

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Greenland Arctic Sea Ice Volume Anomaly:Ice Melt May 31, 2011

Monthly anomaly relative to 1979-2010Trend: -2.8 ± 1.0 in thousands of

km3/decade.

Extensive thinning of margins (-1.5m/yr red, +1.5m/yr blue)

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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.

Observed GHG Emissions and Emission ScenariosEach Emissions Scenario is a guess about our future carbon production

Peters et al. 2012a; Global Carbon Project 2012http://www.globalcarbonproject.org/carbonbudget/index.htm

4.0-6.1°C

2.6-3.7°C

2.0-3.0°C

1.3-1.9°C

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Effectiveness vs.

Affordability

Timeliness[Fast/Slow]

Safety[Low/Medium/High

Geoengineering

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:

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.

T T

Climate Models

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