Not sure if you are referring to manmade CO2. Basic physics says doubling of CO2 concentration would yield a warming of 1.2C. Evidence of warming and higher CO2 levels is thus evidence that global warming is caused by CO2. The other causes part is problematic. Natural variation is the default reason. There is also the possibility of it being both. Historically, CO2 increased after a temperature increase, with a very large time lag. So it is possible that some part of the current CO2 increase is a result of the Medieval Warm Period. That should be a separate question.
Climate scientists have responded that even with this effect, their models say it doesn't matter, the additional natural CO2 only causes a certain portion of the overall warming. However, there is an inherent problem in that they are begging the question. If you take a model that assumes CO2 causes warming, then use that to prove that CO2 causes warming, you haven't accomplished much. It is possible the temperature increase is natural, and CO2 increase is a result of prior warming.
It is not only CO2 that traps heat on Earth. Other common gasses that trap heat are methane and water vapor for example. There is FAR more water vapor in the air than CO2. But the CO2 is constant (except for what we add by burning fossil fuel of course), but water vapor changes wildly all the time. We call it humidity.
There is no argument about how much heat is trapped by a given amount of CO2. It is an easy calculation. And the amount is quite small. The increase in CO2 in Earth's air is only enough to cause a small fraction of one degree change in temperature. It is secondary effects caused by that fractional change that are thought to magnify the effect. For example a fraction of a degree increase in temperature will cause more water to evaporate from the ocean and that increases humidity which adds enough water vapor to raise the temperature more. Or maybe it just causes more clouds to form and that cools the planet. So basically the devil is in the details, as they say.
The planet Venus's atmosphere is 96% CO2 and its a balmy 467 degrees C at the surface.
EDIT: yes but Mars atmosphere is somewhat thinner, less that 1 psi at the surface.
Admittedly comparing the atmospheres of different planets isn't really that helpful, considering 1 day on Venus is about 111 earth days long and somewhat closer to the sun and mars is somewhat further from the sun.
It's a but like comparing apples to running shoes.
:p
There is no proof . The 10 warmest years was the 1930s
when the jet stream went further south.
They are trying to make 2011 and 2012 hot because
of July was hot those years . Thats not a pattern .
That's what I keep asking Warmists.
Here I ask all Warmists to link for me a graph showing CO2 driving temperature, none of them could do it. http://ca.answers.yahoo.com/question/ind...
Now if CO2 actually did drive temperature every Warmists would have about a dozen of these graphs scattered around on their desk --- but nobody could produce one.
I actually gave Best Answer to Hey Dook because his answer was so ridiculous.
Dook posted this graph --- http://creation.com/images/fp_articles/2...
BUT only half of it, he didn't post the "Sun & Temp" half of the graph.
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MTRstudent - Please don't bother to post anything from that Alarmist hive known as SkepticalScience.com --- the site where even it's name is a lie. It's a tailor made site to support man-made Church of Global Warming true believers like yourself and it's hard to find a word of truth on it. Of course, Warmists would be lost without it as you are demonstrating.
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There is a good summary with links back to the original scientific studies on Skeptical Science:
http://www.skepticalscience.com/empirica...
http://www.skepticalscience.com/human-fi...
Probably the most important fingerprint is that satellites directly measure the stronger CO2 greenhouse effect, and they measure that more heat is being trapped. That is causing us to warm up. Meanwhile everthing else that we measure is not causing warming. The Sun, for example, has been cooling for the past 30-50 years.
There are also other 'fingerprints' you expect from CO2 caused warming, like warming down in the atmosphere but cooling in the stratosphere. If it were the Sun then you'd expect the upper atmosphere to warm, but it's cooling as predicted if CO2 is the most important feature.
We know how much heat CO2 is trapping, and we can see what the climate impacts of this are by looking at how the climate responds to other changes in heat. This lets us calculate something called 'climate sensitivity', and estimates of this from both theory and measurements show that global warming is being caused by CO2. This includes things like seeing how temperatures changed after volcanic eruptions, or how ice ages happened in the past.
t
We know all about the 10 warmest yrs, melting icecaps and glaciers, but where is the evidence that ties to CO2, rather than other causes.
