Greenhouse Effect* Two transparent windows:  Solar radiation – visible (  m)  Earth radiation – infrared (7-15  m) Major infrared absorbers: - CH 4, Natural Gas - N 2 O, Nitrous Oxide - O 3, Ozone - CO 2, Carbon Dioxide - H 2 O, Water * Piexoto & Oort CH 4 N2ON2O O 2,O 3 CO 2 H2OH2O P310 BRABSON

IPCC – AR5 – Sept Executive Summary P310 BRABSON

2011 Mauna Loa CO 2 Mauna Loa Monthly Mean CO 2 in parts per million (ppm). August 2013: ppm August 2012: ppm National Oceanic and Atmospheric Administration (NOAA) rends/ P310 BRABSON

Last 1000 years of CO ppm 280 ppm P310 BRABSON

Global Mean Surface Air Temperature to 2012 The graph shows global annual surface temperatures relative to 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) P310 BRABSON

J. Hansen et al., Science 308, 1431, P310 BRABSON

The Millennial Temperature Record Jones, et al – Climatic Research Unit  Proxies: Different choices of Northern Hemisphere proxies (trees, ice cores, corals, lake & marine sediments, and historical documents)  Natural forcing from sun and volcanoes dominate the pre-1850 record and only human activities appear to adequately explain the rise in temperature during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 20 th century Medieval Warm Period Mini Ice Age P310 BRABSON

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 P310 BRABSON

Arctic Sea Ice AREA – September 29, 2013 Positive Feedback Positive Feedback from increased absorption of solar energy by black water. Tipping point? IPCC projected ice free summers by mid-century projections now as early as 2020 Open exploration Open exploration for natural resources. P310 BRABSON

Greenland Arctic Sea Ice Volume Anomaly: Ice Melt May 31, 2011 Monthly anomaly relative to Trend: -2.8 ± 1.0 in thousands of km 3 /decade. Extensive thinning of margins (-1.5m/yr red, +1.5m/yr blue) P310 BRABSON

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 27 o C  increased hurricane severity. P310 BRABSON

Observed GHG Emissions and Emission Scenarios Each Emissions Scenario is a guess about our future carbon production Peters et al. 2012aPeters et al. 2012a; Global Carbon Project 2012Global Carbon Project °C °C °C °C

Effectiveness vs. Affordability Timeliness [ Fast / Slow ] Safety [Low/Medium/High Geoengineering P310 BRABSON

Geological Carbon Sequestration  John Rupp, Indiana Geological Survey, Bloomington  Supercritical fluid above 70 bar  Indiana: ¼ GT/year CO 2  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 P310 BRABSON

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 P310 BRABSON