"We have no alternative to the enhanced greenhouse effect, we have no alternative theory of atmospheric radiation, we have no explanation of the warming based on physically credible models, and we have no basis to believe the greenhouse effect stopped functioning beyond 280ppm of CO2. The skeptics have had 100 years to put a credible alternative forwards - do they need another 100?"
This was a recent and passionate claim from one commentator at this weblog, click here for the thread.
David was referring to the work of Svante Arrhenius who won a nobel prize for chemistry in 1903 and first proposed that changes in the levels of carbon dioxide in the atmosphere could substantially alter the surface temperature through the greenhouse effect.
According to Wikipedia:
"Arrhenius' high absorption values for CO2, however, met criticism by Knut Ångström in 1900, who published the first modern infrared spectrum of CO2 with two absorption bands. Arrhenius replied strongly in 1901 (Annalen der Physik), dismissing the critique altogether. He touched the subject briefly in a technical book titled Lehrbuch der kosmischen Physik (1903). He later wrote Världarnas utveckling (1906), German translation: Das Werden der Welten (1907), English translation: Worlds in the Making (1908) directed at a general audience, where the suggested that the human emission of CO2 would be strong enough to prevent the world from entering a new ice age, and that a warmer earth would be needed to feed the rapidly increasing population. From that, the hot-house theory gained more attention. Nevertheless, until about 1960, most scientists dismissed the hot-house / greenhouse effect as implausible for the cause of ice ages as Milutin Milankovitch had presented a mechanism using orbital changes of the earth."
Arhenius estimated that a doubling of CO2 would cause a temperature rise of 5 degrees Celsius, recent values from IPCC place this value (the Climate sensitivity) at between 1.5 and 4.5 degrees.
NASA reports that, globally, temperatures have increase on average by 0.6 degrees in the past three decades and 0.8 degrees when measured over the last 100 years. What would Arrhenius have estimated the global temperature increase to have been given current levels of carbon dioxide?
Nir Shiviv - "The problem is that the 1.5kW peak is assuming the panels are facing the sun. Since they cannot face it all the time, you lose on that. (In principle, _if_ we had directionally adjusting panels [like a sunflower 😉 ], we could get on average 9.5*1.5 = 14 kWh / day, and then a 4.7 percent loan will already start to save money... assuming the pivoting mechanism doesnt cost money)."
You can get solar trackers for a reasonable price:
http://www.solenergy.com.au/SolarTrackers.htm
The middle one is about AUD$695 so it is quite cost effective. However the biggest benefit is in summer when you do not really need it. I will be using one when I install my system.
Any way you can email me if you would like any more details - this is getting pretty far off-topic.