Greenhouse Effect*. Two transparent windows: Solar radiation – visible (0.3-0.8 m m) Earth radiation – infrared (7-15 m m) Major infrared absorbers: CH 4 , Natural Gas N 2 O, Nitrous Oxide O 3 , Ozone CO 2 , Carbon Dioxide H 2 O, Water. CH 4. N 2 O. O 2 ,O 3. CO 2. H 2 O.
Two transparent windows:
Major infrared absorbers:
* Piexoto & Oort
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/trends/
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)
Medieval Warm Period
Mini Ice Age
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
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
2012projections now as early as 2020
Open exploration for natural resources.
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)
Each Emissions Scenario is a guess about our future carbon production
Peters et al. 2012a; Global Carbon Project 2012
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.