Greenhouse Effect: Trapped Infrared Light Heat Visible light, which our eye is responsive to, is only one small portion of the electromagnetic spectrum. The energy carried by light is dependent upon its oscillation frequency
Greenhouse Effect: Recent Data Recent data and computer simulation models of the global temperature of the Earth’s atmosphere. This plot is shown as a difference from the average (taken when? – to make it look dramatic!) The models use only the carbon dioxide concentration as the changeable variable. This is often used as evidence for global warming caused by rising carbon dioxide levels. Recent data of the carbon dioxide concentration in the Earth’s atmosphere. Since 1960, the average concentration has risen by 55 ppm by 2000. Note the seasonal variations.
Greenhouse Effect?: Long Baseline Data On average, the Earth has been warmer than the estimated mean global temperature of 15 C. Note the ice ages during the Tertiary era. What is driving those oscillations? Outgassing?
Greenhouse Effect: Another Perspective Centered on approximately 1000 years ago, Chepstow-Lusty and Winfield describe "the warm global climatic interval frequently referred to as the Medieval Warm Epoch. An arid interval in South America may have played a significant role in the collapse of the Tiwanaku civilization, where a contemporaneous prolonged drought occurred in and around the area of Lake Titicaca Preceding the Dark Ages Cold Period in both parts of the world was what in the North Atlantic region is called the Roman Warm Period. This well-defined climatic epoch is strikingly evident in the pollen records straddling the BC/AD calendar break with one to two hundred years of relative warmth and significant aridity located on either side of it. Extensive climatic correspondences such as these, occurring between widely separated Northern and Southern Hemispheric regions, are not coincidental; they reveal the existence of a significant millennial-scale oscillation of climate that is global in scope and, hence, driven by a regularly-varying extraterrestrial forcing factor. Although one can argue about the identity of that forcing factor and the means by which it exerts its influence, one thing is clear: it is not the atmosphere's CO2 concentration, which has only varied in phase with the climatic oscillation over the Little Ice Age to Modern Warm Period transition and has exhibited no cyclicity at all over the entire rest of the record. This being the case, it should be clear to all that the climatic amelioration of the past century or more has had absolutely nothing to do with the concomitant rise in the air's CO2 content but absolutely everything to do with the influential extraterrestrial forcing factor that has governed the millennial-scale oscillation of earth's climate as far back in time as we have been able to detect it. Keith Sherwood and Craig Idso (BYU)