Hi David, I'm asking a bit of help about AGW, I simply don't have the time and energy to get the answers myself. The topic turned up in a "debate" with Deniers and I couldn't get the current scientific understanding after cc. an hour of internet search.
It's about Outgoing Long wave Radiation (OLR). The claim was that OLR as measured by satellites shows an increase from 1979. Now I could find gridded OLR data at NOAA but I couldn't find a smoothed and summed curve, so I was unable to check even this (Rule Nr. 1 with Climate Deniers: Check even their simplest/self-evident assertions).
The other claim of theirs was that reduced cloud cover is responsible for around 2 W/m^2 increase in incoming short wave radiation and that is the reason for the "0.66C" (as per claim) increase in temperatures from 1979. In other words, they claim that CO2 has simply no effect on temperature and the whole thing can be explained away by a (probably miraculous) decrease in cloud cover.
I'm sure these arguments are flawed but I simply couldn't find what science had to say about this without reading a shitload of papers. Thanx for any help.
- Instantaneously after an increase in CO2, you have lower OLR (by ~4 W/m2 for 2xCO2) - OLR would then increase as temperature increases. (proportional to the fourth power of Earth's temperature.) - Temperature will increase until outgoing radiation equals incoming (equilibrium) - The real balance is in net energy (not just LW). So for instance, the OLR at equilibrium after an increase in CO2 could be higher or lower depending on the SW feedbacks.
My first answer missed the point. The review was educational. Thanks for bringing this up!
4 comments:
Hi David, I'm asking a bit of help about AGW, I simply don't have the time and energy to get the answers myself. The topic turned up in a "debate" with Deniers and I couldn't get the current scientific understanding after cc. an hour of internet search.
It's about Outgoing Long wave Radiation (OLR). The claim was that OLR as measured by satellites shows an increase from 1979. Now I could find gridded OLR data at NOAA but I couldn't find a smoothed and summed curve, so I was unable to check even this (Rule Nr. 1 with Climate Deniers: Check even their simplest/self-evident assertions).
The other claim of theirs was that reduced cloud cover is responsible for around 2 W/m^2 increase in incoming short wave radiation and that is the reason for the "0.66C" (as per claim) increase in temperatures from 1979. In other words, they claim that CO2 has simply no effect on temperature and the whole thing can be explained away by a (probably miraculous) decrease in cloud cover.
I'm sure these arguments are flawed but I simply couldn't find what science had to say about this without reading a shitload of papers. Thanx for any help.
B.
Shouldn't we expect OLR to increase as the planet warms (proportional to the fourth power of Earth's temperature)?
That was my first thought too :)
Meanwhile I found these:
https://www.gfdl.noaa.gov/blog_held/46-how-can-outgoing-longwave-increase-as-co2-increases/
http://www.realclimate.org/index.php/archives/2016/02/what-is-the-best-description-of-the-greenhouse-effect
http://www.realclimate.org/index.php/archives/2019/01/the-climate-scientists-are-alright
OLR apparently CAN increase and this is not a contradiction.
Good sources. If I'm understanding correctly:
- Instantaneously after an increase in CO2, you have lower OLR (by ~4 W/m2 for 2xCO2)
- OLR would then increase as temperature increases. (proportional to the fourth power of Earth's temperature.)
- Temperature will increase until outgoing radiation equals incoming (equilibrium)
- The real balance is in net energy (not just LW). So for instance, the OLR at equilibrium after an increase in CO2 could be higher or lower depending on the SW feedbacks.
My first answer missed the point. The review was educational. Thanks for bringing this up!
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