Global warming is NOT
There are some scientists that don't believe that global warming is happening at all. There are also many that believe that the slight temperature increase over the last one hundred years is nothing more than a natural fluctuation in the normal cycle. Finally there are some that acknowledge the increase with concern but do not believe it is due to carbon dioxide increases.
Scientists that try to disprove statements that the Earth is warming with time are fighting a tough battle these days. These scientists say that the global warming proponents are using faulty models to show the Earth is warming.  According to their models, over the last one hundred years, the average temperature of the Earth should have increased by one degree Celsius. It has not. It has increased by roughly half a degree Celsius (.45-.6C; which is 1 degree Fahrenheit).  It is believed that since the temperature has not risen the full amount, the Earth is not warming.
The next step in this argument is a logical one. Why is the temperature going up even slightly? Scientists believe that this is due to natural fluctuations in climate. Earth's climate has varied significantly more than this over its six billion year history. This planet has gone through many ice ages and has always reversed them. The climate has also been much hotter than it is now and returned to a more temperate level. Nature will adjust accordingly.
Finally there are scientists that cautiously acknowledge the increase, but don't attribute it to increases in carbon dioxide. They claim that anthropogenic carbon emissions aren't the most important factor in determining what causes temperature variations. They claim that solar variations, including sun spots or flares, could play a major role in the temperature increase.  A 4% decrease in cloud cover, which affects incoming solar radiation, would have the same effect as doubling the carbon dioxide level in the atmosphere. They also claim that even the moon effects climate.  Not enough is known to make a conclusive decision on what effects climate the most.
The increase in carbon dioxide in the atmosphere is not directly related to anthropogenic sources. There are other sources that make much bigger carbon contributions to the atmosphere. Plant decay and volcanic activity along with numerous other natural emitting sources account for 200 billion tons of carbon dioxide while anthropogenic sources account for a mere seven billion tons.  Thus human activity does not make up a major source of carbon dioxide.
Since human activity does not account for a major input of carbon dioxide into the atmosphere, it is difficult to link carbon dioxide directly to the increase in average global temperature. Globalwarming.org says that recent climate changes are not caused by increasing carbon dioxide concentrations in the atmosphere.  Some models show that the cooling effect of fossil fuels, such as the haze emitted from sulfate aerosols, may be between .4-8 times that of the heating effect.  Deforestation and alternate land usage, while anthropogenic, are not direct emissions as burnt fossil fuels are. Thus carbon dioxide is not directly linked to average global temperature increases.
These scientists further argue that correlation between anthropogenic emissions
and global warming are not accurate. The temperature data is not
accurate. Using a more precise satellite, the data shows that there
was a cooling trend globally from 1979 to 1997. Balloon data and
observations verified this as well. Scientists, pro or con, cannot
create a model that incorporates all of the factors because they still
do not know exactly how each factor effects the global temperature scheme.
Water vapor and clouds are thought to affect this scheme, but to what extent
is not known. More information needs to be found in order to accurately
model the atmosphere and how carbon dioxide relates to global warming.
 Zanetti, P., Today's Debate on Global Climate Change: Searching for the Scientific Truth.
 Baliunas, S., 1996. Are Human Activities Causing Global Warming? George Marshall Institute.
 Singer, S. F., 1997. Hot Talk, Cold Science: Global Warmings Unfinished Debate. Oakland: The Independent Institute.
 A site insisting that increased CO2 does not effect global warming and has no negative effects. http://www.globalwarming.org/sciup/sci11-11-99.html