"Perhaps now that the President has acknowledged the existence of global warming and the possibulity that it is due to human activities, the NOAA position will change."

One thing pretty much known without any doubt whatsoever and that is that global warming was not caused by humans.

Whether human activity added to global warming is still not known. What is known without any doubt is that urban areas do increase the temperatures in the local areas- known as Heat Island affect. One could "take" this Heat Island affect and say this affect is increasing global temperature. On a global scale the heat island affect is not measurable- urban areas are too tiny an amount of land area in comparison to the planet, but you do know it's adding some amount of heat. So from this you can claim that there is no doubt that human activity is adding to global warming.
So there is no "possibulity" that global warming is caused by human activity- but if you leave your front door open you are adding to global warming.
Of the .6 +or- .2 C of average global temperature which has risen in last Century or so, no one knows the amount due to all human activity and no one knows how much is added due to say just increased CO2 levels. It is possible that no measurable amount was added to to human activity. Few of even the psendo scientist will claim that all this increase is caused by human activity- even fewer would claim all the increase is due to CO2.

If you talk just about increasing global CO2 levels, it fairly certain that human activity is adding to increasing levels of CO2. But it's not known how much global temperatures would rise if CO2 levels increased by %50 or %100. It as been said that if CO2 levels were to double global temperature would increase by 1 C. But it's possiable that global temperatures could instead rise by 2 C or not rise by a measurable amount.