French mathematician, Jean-Baptiste Joseph Fourier noticed that temperature of Earth was slowly increasing. He termed it Greenhouse effect. In 1850, an instrument became available to record the surface temperature of Earth. 1880s, Scientists associated the relation between human activities and rise of CO2 level in the atmosphere (Chatterjee & Bhattacharya, 2016). The theory of global warming was developed by Swedish chemist Arrhenius around 1895. He calculated that a doubling of CO2 ppm would be conducive to a 5-degree increase in global average temperature, which is not too far off the worst case scenario for the 21st century.
Yet, it was not until Stephen Schneider published Global Warming in 1989 that the theory started to receive wide attention, no doubt strengthened by the work of Keeling in measuring CO2 ppm globally. Moreover, techniques for viewing the CO2 layer were developed, increasing the attention to climate change.
According to John Cook, writing the popular Skeptical Science blog (2010), 10 indicators of a human fingerprint on global warming were observed.
They are shrinking thermosphere, rising tropopause, less oxygen in the air, release of 30 billion tons of CO2 annually, nights warming faster than days, more fossil fuel carbon in coral, more heat return to earth, more fossil fuel carbon in the air, cooling of stratosphere and less heat escape to the space.
Major source of CO2 is fossil fuel burning it contributes more than 75% of atmospheric CO2 in 1990s, further chemical changes during production of lime cement and ammonia augment and increasing litter and garbage decomposition are other anthropogenic means.
Agricultural activities, increased number of cattle and pig dairy farming and non- dairy cattle(ruminants releases methane through their digestive process), termite concentrated areas such as tropical grasslands and forests release a considerable amount of methane to the atmosphere (Crutzenet al., 1986), forest fire events contribute a large amount of methane efflux particularly during ENSO (El Ni?o-Southern Oscillation) Paddy cultivation and various other cultivation produces flooded wetlands which generate methane during anaerobic decomposition. Coal mining process leakage through the pipelines and drilling for oil are major anthropogenic sources (Hengeveld, 1991 as cited in Kemp, 2004). Anaerobic decaying of landfill organic wastes and piling of garbage and fertilizer are another source of methane, venting, flaring at oil and gas wells, enteric fermentation, biomass burning and burning of fossil fuels are few other anthropogenic sources.
Considering the probable damages from global warming, it is astonishing that the global warming theory has not been better recognized or even conceptually developed or empirically corroborated. There will be sooner or later:
This list is far from complete or exhaustive. One could even mention worse outcomes, like the transformations of warm and cold currents in the oceans, Gulf Stream, North Atlantic Current for example. What one may underline is that so far, no known negative feedback has been found that could stem global warming naturally. We seem to have mainly only positive feedbacks, meaning outcomes reinforce each other in the same direction. The situation in the Amazons and Borneo is basically lost, and Siberian forests threatened.