GISS 1997 Global Station Data Showed That CO2 Sensitivity Was Almost 3X Higher Below 310 PPM

5 Responses to GISS 1997 Global Station Data Showed That CO2 Sensitivity Was Almost 3X Higher Below 310 PPM

1. daveburton says:

   December 24, 2013 at 12:29 am

   Interesting graph. It is true that adding 1 ppm CO2 has more warming effect at 310 ppm than at 400 ppm, but 3x is waaaaay too large of a ratio.

   We’re way past the “point of diminishing returns” on temperature from additional CO2. For any trace GHG, adding additional amounts to the atmosphere has a diminishing effect on the atmosphere’s absorption of IR in the associated absorption bands as the trace GHG concentration goes up. Just as the first drop of blue food coloring added to a bowl of water has a dramatic effect on its color, but the addition of more drops of blue food coloring has a diminishing effect, so GHGs “color” the atmosphere in the IR region, and have diminishing effects as their concentrations go up. That’s why GHGs with very low concentrations are said to be more “potent” as GHGs: because the wavelengths that they block aren’t already mostly blocked.

   MODTRAN calculates that 50% of the warming effect of current (400 ppm) CO2 level would be accomplished by just 20 ppm CO2 (for a tropical atmosphere w/ constant relative humidity):
   http://www.burtonsys.com/climate/MODTRAN_etc.html

   The NCAR radiation code says that 40 ppm CO2 would be needed to get 50% of the current CO2-caused warming, rather than 20 ppm, but, either way, the lesson is clear: we’re well past the point of diminishing returns w/r/t the warming effect of CO2.

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2. Andy DC says:

   December 24, 2013 at 12:48 am

   I heard nearly 40 years ago from a U of MD professor who taught radiation theory that the effect of CO2 as a greenhouse gas would rapidly diminish as more was added to the atmosphere. That is a dirty little secret that alarmists don’t want you to know.

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3. Tel says:

   December 24, 2013 at 12:57 am

   You are supposed to adjust CO2 level to a log scale. That’s the theory of the “per-doubling” although there’s a lot of online climate science advocates who don’t understand that.

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4. Richard111 says:

   December 24, 2013 at 9:03 am

   Baffled layman query; CO2 can absorb high energy photons from the sun in the 2.7 and 4.3 microns bands. This warms air which rises, absorbed energy never reached the surface. A shading, or cooling effect. There is possibly more radiation from the surface in the 15 micron band than is received from the sun. Problem is CO2 has low heat capacity and is surrounded by warm air causing the CO2 molecules to emit 15 micron photons. Absorb one, emit one, no energy change. After sunset no 2.7 or 4.3 micron photons. Please talk me through the science of how CO2 warms the air causing the SURFACE to be 33C warmer and what is the direct path of this energy flow and or what and where are the ‘heat reservoirs? I note LWIR does not warm ocean water below surface mixing level due turbulence. Only sunlight can warm ocean to 100 metres or so.
   Just a good link will do. TIA

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5. Morgan Wright says:

   December 24, 2013 at 9:51 am

   Whatever greenhouse effect CO2 has is trivial, we should ask these questions about H2O which is responsible for 92% of the greenhouse effect. Talking about the CO2 is a waste of time, we might as well be talking about CH4

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