CO2 IS a greenhouse gas. -

TAFKASE:True on Venus where the concentrations are many magnatudes higher than on earth. We also think it has a small effect on Earth, although how much of an effect is not known entirely...Which is why we are having this argument. The only way to know for sure is to speculate of climate models with a lot of unknown variables...

Right off the bat you start with Venus- no serious scientist is claiming that we are in danger of turning the earth into venus. We KNOW CO2 acts as a greenhouse gas on Earth, this is not in doubt. In part it is what allows the Earth to be at the hospitable warm temperature it is now. CO2 absorbs IR radiation that the Earth would normally radiate out to space. (Lets be precise here, CO2 is the most commonly referred to greenhouse gas, but there are other important gasses, and they are ALSO increasing). Increasing CO2 increases the amount of energy from the sun that remains on the Earth. Climate models are getting better and better and have been converging to a common answer, granted their is always some uncertainty- but they all agree that human green house gasses will lead to warming. They have been able to model the observed changes fairly well.

Humans are releasing large amounts of CO2 -

ASKFATE:Well I guess so... But compared to what? If there were no humans?
Seriously, how does all human releases compare to a single forest fire? Are human activities causing forest fires? Maybe...But maybe in ways that aren't what they seem...in fact, many forest fires might be caused my misguided environmental policies.

This is a typical tactic... Sure, the burning of biomass like grasslands and forests contributes to CO2 and thus it contributes to global warming. It is also a fact that most burning of biomass is directly attributable to human activities:

"The major components of biomass burning are forests (tropical, temperate, and boreal); savannas; agricultural lands after the harvest; and wood for cooking, heating, and the production of charcoal (Box 1). The burning of tropical savannas is estimated to destroy three times as much dry matter per year as the burning of tropical forests. The vast majority of the world's burning is human-initiated, with lightning-induced natural fires accounting for only a small percentage of the total.
FROM:http://www.virtualcentre.org/en/dec/toolbox/Indust/BioBurEA.htm
(Other sources, such as a NASA article say up to %90 of biomass burning is human initiated)

Nor can you blame volcanoes:

"Comparison of CO2 emissions from volcanoes vs. human activities.

Scientists have calculated that volcanoes emit between about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere every year (Gerlach, 1999, 1991). This estimate includes both subaerial and submarine volcanoes, about in equal amounts. Emissions of CO2 by human activities, including fossil fuel burning, cement production, and gas flaring, amount to about 27 billion tonnes per year (30 billion tons) [ ( Marland, et al., 2006) - The reference gives the amount of released carbon (C), rather than CO2, through 2003.]. Human activities release more than 130 times the amount of CO2 emitted by volcanoes--the equivalent of more than 8,000 additional volcanoes like Kilauea (Kilauea emits about 3.3 million tonnes/year)! (Gerlach et. al., 2002)"
FROM:http://volcanoes.usgs.gov/Hazards/What/VolGas/volgas.html

In addition to producing CO2 a higher than the steadystate rate we are also destroying large sinks of CO2, sometimes destroying them via BURNING! The Rainforests are being cut and burned at a large rate,as are forests elsewhere.

There is no serious doubt that the MEASURED increase in CO2 is largely due to human activity.

SEAFAKT:What sinks? Peat bogs? Swamps? I guess you are talking about oil deposits...Don't many of those also release methane which is another greenhouse gas? If we are removing sinks, then that process could be reversed by planting more trees

Statements like this are what make me think that you are intellectually lazy. You KNOW that is a ridiculous statement. Oil and Coal are essentially eons worth of sequestered carbon, we are taking all that sequestered carbon, built up over eons, and turning it into CO2. That carbon would have remained in the ground for eons more if we werent extracting it, and whatever would be released naturally would be released over millions of years, not over a century! As for planting more trees, well fine lets do that, but look at the numbers above, and see how much more CO2 we are creating than the natural rate. We need to reduce CO2 production and instead we are accelerating it- India and China are only going to grow.

TAFKASE:...But what are these sinks? And how big are they really in relation to the size of Earth's atmosphere? Surely there are some sinks which are in fact getting smaller, but aren't there also sinks that are getting larger? How can and do we measure these sinks?

The carbon pool sizes in the boxes are expressed in Gt C (Gt C = 10^15 g C). Annual increments expressed in Gt C per year are shown in parentheses. All fluxes indicated by the arrows are expressed in Gt C per year. The inferred net terrestrial uptake of 0.7 Gt C per year considers gross primary production (~101.5), plant respiration (~50), decomposition (~50), and additional removal from the atmosphere directly or indirectly, through vegetation and soil and eventual flow to the ocean through the terrestrial processes of weathering, erosion, and runoff (~0.8). Net ocean uptake (~1.6) considers air/sea exchange (~92.4 gross uptake, -90.8 gross release). As the rate of fossil fuel burning increases and CO2 released to the atmosphere it is expected that the fraction of this C remaining in the atmosphere will increase resulting in a doubling or tripling of the atmospheric amount in the coming century.

The fact is we are putting CO2 into the atmosphere faster than it is being removed, the level of CO2 in the atmosphere is growing, and the effects it has will grow as well. We are already seeing warming as a result and we know that unless action is taken that warming will increase. What part of this do you have a problem understanding? Not only is it common sense, it is confirmed by hard data, and comprehensive models that all qualitatively agree.

The data also indicate that this rise is from human activity, not natural causes -

FAKESAT: Now here I disagree slightly...but hey... I'll agree just to be agreeable...So what... We are talking a mininscual amount overall compared to Water Vapor concentrations...How many H2O molecules are in the air compared to CO2 molecules? Which do you think has a bigger Greenhouse effect? is it the H2O molecules in the air or is it the CO2 molecules? Should I feel guilty every time I go in the steam room because opening the door saturates the local atmosphere with H2O molecules?

Either be serious or shut up, please! Of course other gasses play a role in global warming, H2O and methane are also important, as are others which, like methane, we are also increasing.

The data also show, as is to be expected, the temperature is rising.

EATFAKS:ok I agree over the last 100 years, the tempature is about 1 degree higher... We're not dying from that...Nor would we all die if it rose another 1-2 degrees over the next 100 years... In fact, the Earth might be a more pleasant place should that occur! But even still, why is the Ice cap in Antartica getting BIGGER if this warming is occuring which we agree that we THINK is occuring...

Again you have latched onto another popular talking point. The global change does NOT have to be uniform at all. The fact is that worldwide glaciers are melting rapidly, so is the arctic... this WILL lead to sea level increase, it IS leading to water shortages. We have seen time and again how regional short term fluctuations in climate have wreaked havok on food production. We have built the infrastructure of our civilization on a foundation of a steady climate, and now it looks like that will be harshly taken away. There will be coastal flooding, there will be changes to crop production, there will be humanitarian disasters and displaced people as a result. We are already seeing territorial conflicts building over the artic. There is EVERY reason to believe that if the foundation we have built on is suddenly changed that the result will NOT be a more pleasant place to live.

Even you have to admit that action WILL have to be taken at some point, if not at 1 degree, what about 3... what about 7... why are you so opposed to taking action before the REALLY serious damage is done?

Can you point to even ONE time where I have posted bad science on this board? -

EAKSFAT:No I can't, but even if I could, why would I? Even if you had posted bad science in the past, We are talking about the science of global warming here, not science in general...

My point was that I do not make scientific claims on the basis of politics- this is NOT a political issue, it just IS! You insist on making this about politics!