3 ms·

I just did a back of the envelope calculation. A change of 0.5 W/m^2 would yield (in equilibrium) an increase of 0.4 degrees C based on basic heat transfer. I

by iaw 12y ago

I just did a back of the envelope calculation. A change of 0.5 W/m^2 would yield (in equilibrium) an increase of 0.4 degrees C based on basic heat transfer. I see them dismissing the significance of solar irradiance but no where do I see them explain their methodology for determining the relationship of solar irradiance to temperature. 1% of 1300 W/m^2 is still a significant amount of extra energy that the planet needs to dissipate. Also, while the lead author of that paper is a physicist, looking at his published history he seems firmly biased into the realm of particulate/aerosol driven climate impacts. It would be against his academic interests to publish a paper that at all discounts his historic work. If you have any knowledge of papers that try to quantify and link solar irradiance changes to global climate change I'd be interested in reading over their methodology. I just didn't see that in here (correct me if I'm wrong).

jjoonathan 12y ago
Yeah, they don't discuss methodology in the summaries, and it's a PITA to chase down their references. It looks slightly easier in AR5 so I'll switch to that one. First of all, did you multiply by the geometric and albedo factors (0.25 and 0.7 respectively)? Because 0.5W/m^2 * 0.25 * 0.7 is 0.9W/m^2 which is within the range given in 5AR in the context of this energy-balance comparison (made in units of radiative forcing): Effective RF due to all anthropogenic effects: 1.1-3.3W/m^2 Effective RF due to greenhouse gasses: 2.54-3.12W/m^2 Effective RF due to non-CO2 GHGs: 0.43-0.53 W/m^2 RF due to Solar Forcing: 0.05-0.10W/m^2 These numbers indirectly answer your question (solar forcing is estimated to only be accountable for a fraction of the ~1ºC warming we have seen thus far) but I'm afraid that the detailed methodology is buried in a completely different section of the report (probably because it involves models of steady-state equilibrium between energy reservoirs now). I don't have the time to dig it up today and I'm not a subject expert, I am just loath to let people get away with the "scientists haven't considered..." type arguments when they're so blatantly wrong. 5AR (solar forcing on page 688): http://www.climatechange2013.org/images/report/WG1AR5_Chapter08_FINAL.pdf http://www.climatechange2013.org/images/report/WG1AR5_Chapte...

by iaw 12y ago

jjoonathan 12y ago

Yeah, they don't discuss methodology in the summaries, and it's a PITA to chase down their references. It looks slightly easier in AR5 so I'll switch to that one. First of all, did you multiply by the geometric and albedo factors (0.25 and 0.7 respectively)? Because 0.5W/m^2 * 0.25 * 0.7 is 0.9W/m^2 which is within the range given in 5AR in the context of this energy-balance comparison (made in units of radiative forcing): Effective RF due to all anthropogenic effects: 1.1-3.3W/m^2 Effective RF due to greenhouse gasses: 2.54-3.12W/m^2 Effective RF due to non-CO2 GHGs: 0.43-0.53 W/m^2 RF due to Solar Forcing: 0.05-0.10W/m^2 These numbers indirectly answer your question (solar forcing is estimated to only be accountable for a fraction of the ~1ºC warming we have seen thus far) but I'm afraid that the detailed methodology is buried in a completely different section of the report (probably because it involves models of steady-state equilibrium between energy reservoirs now). I don't have the time to dig it up today and I'm not a subject expert, I am just loath to let people get away with the "scientists haven't considered..." type arguments when they're so blatantly wrong. 5AR (solar forcing on page 688): http://www.climatechange2013.org/images/report/WG1AR5_Chapter08_FINAL.pdf http://www.climatechange2013.org/images/report/WG1AR5_Chapte...