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==Science of Global Warming==
===Presence of CO2===
One of the primary concerns of Global Warming research is the increased presence of carbon dioxide in the atmosphere. Original claims stated that the increase in carbon dioxide - which is a greenhouse gas - were caused primarily through the burning of [[fossil fuels]], and that such increases were the foremost cause of global temperatures rising. Historically, Global temperature changes precede changes in carbon dioxide in the atmosphere.<ref> [http://www.skepticalscience.com/co2-lags-temperature.htm]</ref>
The most obvious way that this would occur would be through the evaporation of ocean water. The oceans are the single largest storage unit for carbon dioxide gas on the planet, containing about 93% of the Earth's carbon dioxide. <ref> [http://www.waterencyclopedia.com/Bi-Ca/Carbon-Dioxide-in-the-Ocean-and-Atmosphere.html] </ref> As temperatures rise, ocean water evaporates, causing the dissolved carbon dioxide gas to enter the atmosphere, and begin trapping radiation from the sun. Scientists now believe that this cycle causes a sort of chain effect, where increased temperature causes more carbon dioxide to enter the atmosphere, which in turn causes more temperature rise.
It is also noteworthy to point out that carbon dioxide, while not as abundant in the atmosphere, has a more significant effect on global warming than water vapor does. Carbon dioxide cannot form clouds, as water vapor does. When water vapor forms clouds, those clouds actually block some of the sun's radiation from reaching the Earth, causing water vapor to both contribute positively and negatively to global temperature rise. Carbon dioxide can only act as a greenhouse gas, causing the above mentioned cyclic effect. The current concentration of carbon dioxide in the Earth's atmosphere is about 392 ppm, which is the highest it has been in at least 800,000 years.<ref>"Trends in Atmospheric Carbon Dioxide" [http://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html NOAA], December 2011</ref>
===The Modern Warm Period===
The Average [[Earth]] surface air temperature has risen about 1° F since 1970.
<ref>Hansen's group at the Goddard Institute wrote, "Global warming is now 0.6 °C [1.0 °F] in the past three decades and 0.8 °C [1.4 °F] in the past century." http://data.giss.nasa.gov/gistemp/2005/</ref> Studies have ruled out the possibility that errors in the measurements and sampling significantly affect the temperature trends detected over the past century. This accounts for spatial errors in the sampling and thus also incorporates errors associated with the urban-heating effect. According to Karl et al. (1993) ''"Results imply that the errors associated with century-scale trends of temperature are probably an order of magnitude smaller than the observed global warming of nearly 0.5°C per 100 years since the late nineteenth century"'' <ref>http://adsabs.harvard.edu/abs/1994JCli....7.1144K Karl et al. (1993) 'Global and Hemispheric Temperature Trends: Uncertainties Related to Inadequate Spatial Sampling' in Journal of Climate, 7(7); 1144 - 1168</ref>
According to temperature reconstruction made within an [[Old Earth]] paradigm, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). Some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere. However, many scientists also think that human activities were most likely the cause of the the planet's recent warming.
Recent studies of the Milankovitch Cycles, which predict Earth's climate by studying changes in its orbit and axial tilt, suggest that we are currently 18,000 years into a 150,000 year period between ice ages. This would imply that we should expect the temperature to be rising anyway. A 2002 study by Berger and Loutre suggests 50,000 years of warmer weather before Earth begins to cool again, but that model incorroprated anthropogenic forces and concluded:
<blockquote>While combinations of natural forcings produce a gradual warming up to about 1960, none of them leads to a warming over the last 30 years (this period containing three major volcanic eruptions). In contrast, simulations incorporating only anthropogenic forcings reproduce the warming over the last three decades at a rate consistent with that observed, but underestimate the early 20th century warming. As a consequence, only the use of both natural and anthropogenic forcings allows to reproduce much of the observed decadal scale variations of the annual mean hemispheric temperature over the last 150 years.<ref>[http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0870.2002.00287.x/full] Climate of the last millennium: a sensitivity study, May 2002</ref></blockquote>
It should be noted, however, that computer simulated climate models are often tweaked so they agree with the historical temperature record. There is no way to completely simulate all of the Earth's climate with a computer program.
===Sun Spots===
Sunspot activity is a factor in climate fluctuations, however, little details were known about how much of an impact these fluctuations had on the Earth's climate. During the deepest solar minimum ever recorded, from 2005 to 2010, NASA measured the Earth's energy balance, i.e. the amount of energy absorbed by the sun subtract the amount of energy lost to radiation into space. They concluded:
<blockquote>If the Sun were the only climate forcing or the dominant climate forcing, then the planet would gain energy during the solar maxima, but lose energy during solar minima. The fact that Earth gained energy at a rate 0.58 W/m2 during a deep prolonged solar minimum reveals that there is a strong positive forcing overwhelming the negative forcing by below-average solar irradiance. That result is not a surprise, given knowledge of other forcings, but it provides unequivocal refutation of assertions that the Sun is the dominant climate forcing. <ref>[http://www.giss.nasa.gov/research/briefs/hansen_16/ NASA: Earth's Energy Imbalance] nasa.gov, January, 2012</ref></blockquote>
However, just because the sun isn't the dominate force, doesn't mean that it doesn't nonetheless have a significant impact upon the Earth's climate.
==Economics of Global Warming==
==Economics of Global Warming==