There has been skepticism during the entire lifetime of the theoretical atmospheric anomaly called “Global Warming”. Global Warming is a term coined to describe the unnatural rise of the mean low-level atmosphere temperature over a period of time called climate. Global Warming has also been described as Climate Change although it is not a deserved alias as the earth’s climate often changes in temperature over long periods of time (see ice ages and medieval warming). As such, Global Warming should have been coined as the 21st century Global Warming Trend instead of its current names.
The evidence of Global Warming has seemed to pile-up over the time span of its coined existence. This could be due to the fact that more investigations into the global climate heating has resulted in both expected and unexpected evidence and it could be a result of ongoing changes that take place in real time such as the breaking off and thinning of glaciers. Some of the evidence already observed include a research study by various scientists and reported by the Intergovernmental Panel on Climate Change (IPCC) include a global mean temperature increase of 0.74 ± 0.18 °C (1.33 ± 0.32 °F) over the period of the last century although it seems variations in solar radiation and volcanic activity was the primary contributors before the pre-industrial times before 1950.
It is forecasted by the IPCC that the global mean temperature could increase yet another 1.1 to 6.4 °C (2.0 to 11.5 °F) by 2100. The uncertainty in the predicted temperature increases is partially due to the fact that different models have forecasted different amounts of chemicals such as Carbon Dioxide in the atmosphere during varying spans of time. The prediction of 2 °F is a conservative guess but the 11.5 °F increase is also quite possible and would be, of course, the worst case scenario.
The NASA Goddard Space Institute estimated that 2005 was the warmest year globally since dependable and accurate modern satellite temperature monitoring began, exceeding the previous record established in 1998 by only a few hundredths of a degree. The high temperatures recorded in 1998 is thought to be a result of an unusually strong El Niño event – the strongest in over a century.
Since global temperatures have been monitored and recorded, various global locations seem to heat faster than others such as the difference in ocean temperatures relative to land-based atmosphere temperatures. Ocean temperatures rise approximately 0.13 °C relative to land-based atmosphere temperatures which rise an average of 0.25 °C during the course of a decade. Many factors contribute to the difference in temperature increases including the ocean having a vast depth and spread in which temperature is required to increase as well as the effect of evaporation on the air above the ocean. Liquids warm and cool much slower than the air, being more dense, thus the difference in temperature fluctuations. Also, the north hemisphere would warm much faster than the southern hemisphere mainly due to the fact that the northern hemisphere has more land area than does the south. With upper air currents in combination with the difference in temperature, the polar regions would heat much faster than regions closer to the equator, thus the rapid warming and thinning of the polar ice caps in the Arctic and Antarctic Circles. Due to the heat-retaining capacity of the oceans as well as the lifespan of Carbon Dioxide, even if all emissions were to cease the global temperature would continue to rise well after 2100.
Another area which affects the global mean temperature is the effects of “Greenhouse Gases” originally discovered and coined by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. “Greenhouse Gases” are gases which emit and absorb infrared radiation in the planets atmosphere and enhance the atmosphere’s ability to withhold heat energy. “Greenhouse Gases” include but are not limited to: Water Vapor, Methane, Carbon Dioxide, Nitrous Oxide and Tropospheric Ozone. Higher concentrations of these gases lead to the planet’s atmosphere retaining more heat than it exerts thus raising the global mean temperature. Since the industrial revolution, global carbon dioxide levels have increased by 36% – ¾ of the increase is suspected to be a direct result of the burning of fossil fuels. Evidence extracted from deep ice pockets suggest that carbon dioxide levels are higher than they have been in the last 650,000 years – additional evidence is believed to indicate that levels are actually higher than they have been in the last 20 million years. Although most of the gases mentioned enhance the planets ability to retain heat, some chemicals known as aerosols which are either released naturally, as is the case with volcanoes, or by human sowing as is the case with some CFCs. These chemicals reflect radiation back into space from the upper atmosphere countering the effects of “Greenhouse Gases”. Although this may have been the case up until now, it seems as if the amount of “Greenhouse Gases” such as carbon dioxide and methane are well exceeding the amount of aerosol in the atmosphere. This may have been the reason that extreme global mean temperature increase was delayed during the latter half of the 20th century and only become urgent from the beginning of the new millennium onward. Methods have also been used by scientists to combat global warming indirectly and directly including the use of Biochar, Geoengineering and the like.