http://www.britannica.com/EBchecked/topic-art/245233/85040/The-greenhouse-effect-on-Earth-Some-incoming-sunlight-is-reflected
http://www.britannica.com/EBchecked/topic/235402/global-warming
<<<< Earth’s energy budget is further complicated by the greenhouse effect. Trace gases with certain chemical properties—the so-called greenhouse gases, mainly carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)—absorb some of the infrared radiation produced by Earth’s surface. Because of this absorption, some fraction of the original 70 units does not directly escape to space. Because greenhouse gases emit the same amount of radiation they absorb and because this radiation is emitted equally in all directions (that is, as much downward as upward), the net effect of absorption by greenhouse gases is to increase the total amount of radiation emitted downward toward Earth’s surface and lower atmosphere. 

A similar picture is at
http://en.wikipedia.org/wiki/File:The_green_house_effect.svg
Carbon dioxide, methane, and water vapour are the most important greenhouse gases. To a lesser extent, surface-level ozone, nitrous oxides, and fluorinated gases also trap infrared radiation. Greenhouse gases have a profound effect on the energy budget of the Earth system despite making up only a fraction of all atmospheric gases. The greenhouses phenomena is not something new to science, being first identified by Joseph Fourier in 1824.

The following is from the encyclopedia Britainnica.
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Water vapour is the most potent of the greenhouse gases in Earth’s atmosphere, but its behaviour is fundamentally different from that of the other greenhouse gases. The primary role of water vapour is not as a direct agent of radiative forcing but rather as a climate feedback—that is, as a response within the climate system that influences the system’s continued activity. This distinction arises from the fact that the amount of water vapour in the atmosphere cannot, in general, be directly modified by human behaviour but is instead set by air temperatures. The warmer the surface, the greater the evaporation rate of water from the surface. As a result, increased evaporation leads to a greater concentration of water vapour in the lower atmosphere capable of absorbing infrared radiation and emitting it downward.
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In effect, if the atmosphere has reached an equilibrium temperature, by itself water vapor cannot cause the temperature to change.

Insolation is a measure of solar radiation energy received on a given surface area in a given time.

Past and future of daily average insolation at top of the atmosphere on the day of the summer solstice, at 65 N latitude. The green curve is with eccentricity e hypothetically set to 0. The red curve uses the actual (predicted) value of e. Blue dot is current conditions, at 2 ky A.D.

Isolation is affected by the eccentricity variations of earths orbit, precession of the axis of rotation of the earth, and the obliquity of that axis to the plane of the solar system. The figure shows that predicted amount of insolation based on the geometrical relation of the earth with respect to the sun is below the predicted average and should have been decreasing for the past 10 years. You would expect that global temperatures would also decrease because the earth is receiving less energy from the sun.

This figure shows the measured insolation trending down over the last 30 years and especially during the last sun spot cycle (the 11 year sun spot cycle is clearly visible in the insolation measurements). Again, you would expect for global temperatures to decrease as insolation decreased.

The sun spot cycle is not as pronounced in the graph of global temperatures but still discernable. Global temperatures have increased by nearly one degree centigrade over the past century.

Given that insolation has decreased for at least the last 30 years while global temperatures have increased, the conclusion must be that varing insolation is not the cause of increasing temperatures for the last 30 years. Furthermore, insolation has varied over the last hundred years by has exhibited no trend that would explain the increase in global temperatures.

Greenhouse Effect: a warming of the Earth’s surface and troposphere (the lowest layer of the atmosphere), caused by the presence of water vapour, carbon dioxide, methane, and certain other gases in the air. Of these gases, known as greenhouse gases, water vapour has the largest effect.

The atmosphere allows most of the visible light from the Sun to pass through and reach the Earth’s surface. As the Earth’s surface is heated by sunlight, it radiates part of this energy back toward space as infrared radiation. This radiation, unlike visible light, tends to be absorbed by the greenhouse gases in the atmosphere, raising its temperature. The heated atmosphere in turn radiates infrared radiation back toward the Earth’s surface. (Despite its name, the greenhouse effect is different from the warming in a greenhouse, where panes of glass transmit visible sunlight but hold heat inside the building by trapping warmed air.)

Without the heating caused by the greenhouse effect, the Earth’s average surface temperature would be only about −18 °C (0 °F). On Venus the very high concentration of carbon dioxide in the atmosphere causes an extreme greenhouse effect resulting in surface temperatures as high as 450 °C (840 °F). >>>>

Atmospheric Carbon

http://earthobservatory.nasa.gov/Features/CarbonCycle/carbon_cycle.php
The amount of carbon taken up by photosynthesis and released back to the atmosphere by respiration each year is 1,000 times greater than the amount of carbon that moves through the geological cycle on an annual basis. [The geological cycle (operates over millions of years) describes the subduction of ocean sediment under the continents where it is heated, releasing carbon dioxide through volcanoes].
The amounts of carbon that move from the atmosphere through photosynthesis, respiration, and back to the atmosphere are large and produce oscillations in atmospheric carbon dioxide concentrations (see Keeling curve). Over the course of a year, these biological fluxes of carbon are over ten times greater than the amount of carbon introduced to the atmosphere by fossil fuel burning.
Over periods of years to decades, significant amounts of carbon can be stored or released on land. For example, when forests are cleared for agriculture the carbon contained in the living material and soil is released, causing atmospheric carbon dioxide concentrations to increase. When agricultural land is abandoned and forests are allowed to re-grow, carbon is stored in the accumulating living biomass and soils causing atmospheric carbon dioxide concentrations to decrease. >>>>

http://en.wikipedia.org/wiki/File:Carbon_Dioxide_400kyr.png

Note that carbon dioxide levels stayed below 310 ppm until after the beginning of the industrial revolution.

http://earthobservatory.nasa.gov/Features/CarbonCycle/carbon_cycle4.php

More to follow.
 

Not all of the carbon dioxide that has been emitted by human activities remains in the atmosphere. The oceans have absorbed some of it because as the carbon dioxide in the atmosphere increases it drives diffusion of carbon dioxide into the oceans. However, when we try to account for sources and sinks for carbon dioxide in the atmosphere we uncover some mysteries. For example, notice in Figure 1 (schematic of the carbon cycle) that fossil fuel burning releases roughly 5.5 gigatons of carbon (GtC [giga=1 billion]) per year into the atmosphere and that land-use changes such as deforestation contribute roughly 1.6 GtC per year. Measurements of atmospheric carbon dioxide levels (going on since 1957) suggest that of the approximate total amount of 7.1 GtC released per year by human activities, approximately 3.2 GtC remain in the atmosphere, resulting in an increase in atmospheric carbon dioxide. In addition, approximately 2 GtC diffuses into the world’s oceans, thus leaving 1.9 GtC unaccounted for. Several scenarios could cause the land to take up more carbon dioxide than is released each year. For example, re-growth of forests since the massive deforestation in the Northern Hemisphere over the last century could account for some of the missing carbon while changing climate could also contribute to greater uptake than release.
 

NOAA has many satelites that measure various aspects of the earth (e.g., surface temperature, chlorophyll and phytoplankton, solar radiance absorption, fluxes of trace gases at the air-sea interface, changes in land use and ocean primary productivity (rate of carbon fixation from the atmosphere).

Note that the temperature did not start increasing until aftere 1910 or later even though carbon dioxide concentrations had been increasing since the 1850's or earlier.

http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf

The questions asked in the survey:
This brief report addresses the two primary
questions of the survey, which contained
up to nine questions (the full study
is given by Kendall Zimmerman [2008]):
1. When compared with pre-1800s
levels,
do you think that mean global temperatures
have generally risen, fallen, or
remained relatively constant?
2. Do you think human activity is a significant
contributing factor in changing
mean global temperatures?

The results:

Read this paper and then tell me if you still think it is rigged.

I suggest the following link as the root link to explore this question. It contains many links to supporting documentation for the conclusions stated. There are other pages on this web site that are also of interest.
http://www.newscientist.com/article/dn11654-climate-myths-many-leading-scientists-question-climate-change.html