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

* Piexoto & Oort

CH4

N2O

O2,O3

CO2

H2O

P310 BRABSON

P310 BRABSON

IPCC – AR5 – Sept. 2013Executive Summary

P310 BRABSON

P310 BRABSON

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/

P310 BRABSON

Last 1000 years of CO2400 ppm

280 ppm

P310 BRABSON

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)

P310 BRABSON

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Proxies: Different choices of Northern Hemisphere proxies (trees, ice cores, corals, lake & marine sediments, and historical documents)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

P310 BRABSON

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 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.

P310 BRABSON

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

Monthly anomaly relative to 1979-2010

Trend: -2.8 ± 1.0 in thousands of km3/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

StreamOcean 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 2012

http://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

P310 BRABSON

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

P310 BRABSON

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