What evidence is there that increased atmospheric CO2 has caused increased global temperature?

I too would love to see some.

Lab tests show co2 absorbs 3 narrow bands of longwave radiation (this bit there is evidence for at least), and if the "opacity" of co2 in the atmosphere increases, more energy should be absorbed causing increased "emission". This is the hypothesis.

Rising temperatures combined with rising co2 imply a link, though correlation (a very poor correlation) doesnt mean causation, so this is not evidence and the proxy data and reconstructions are subject to high uncertainty so again no credible data there either.

Rising temps since the 1800's also correlate (in fact better than co2) with decreasing pirate numbers, an example of correlation not meaning causation!

The UN’s projected human fingerprint – tropical mid-troposphere warming at thrice the surface rate – is absent (Douglass et al., 2004, 2007; Lindzen, 2001, 2007; Spencer, 2007). So the UN's predicted evidence for global warming isnt their.

Empirical data such as the earths co2 and temperature history show co2 has never driven the earths climate, so in reality it appears co2 doesnt cause warming and thus we probably dont fully appreciate the various feedbacks and radiative-convective effects in the greenhouse effect. This data wasnt previously available when the global warming theory developed, but now it is available, it is aparent the theory of co2 being a key climate driver is misplaced, so there is now less evidence than there was before.

The earths climate history supports radiative forcing as the key natural climate driver for the earth rather than co2 as is accepted by the IPCC in AR4 (though ignored in their models).

So essentially after $50billion dollars of work there is still no evidence. Evidence to the contrary is increasing as fast as the earth is cooling, and as one recent peer reviewed paper put it "Our review suggests that the dissenting view offered by the skeptics or opponents of global warming appears SUBSTANTIALLY MORE CREDIBLE than the supporting view put forth by the proponents of global warming"

Are we on the cusp of a paradigm shift?

I look forwards to a convincing argument from the alarmists, maybe even reference to something scientific, maybe even a peer reviewed paper.

I think this question has been asked, oh about a million times on here. I doubt that any denier would ever accept anything as "proof." Look, there's never going to be a laboratory experiment with two Earths that only differ in the concentration of carbon dioxide. But

1. CO2 has several absorption bands in the infrared, so it is a greenhouse gas. There is really no disputing this.

2. The global mean temperature has been going up on average over the past several decades, as CO2 levels have really started ramping up.

3. High CO2 has been associated with warm periods in Earth's past. There is a time lag, because it has not been the driver in the past, but still a contributing factor. Now it has become a driver.

4. Climate models can be run with and without increased CO2 and the ones with increased CO2 show warming.

5. Dana has already mentioned upper atmosphere cooling.

6. There have been statistical studies which "prove" the connection to CO2, but I doubt that you'd buy into them--I have a hard time with those myself.

My question for you is, what would you consider "evidence?" I hear all the time that "there is no proof..." but I think that's just because you don't believe in circumstantial evidence. Tell us, what would you consider proof? I'm talking about something real and concrete now, tell the scientists what you want and maybe we could provide it.

The Co2 as a problem up through the late 30s was only a small fringe religious group until Dow started funding them to make Co2 look nasty so they could promote their new Freon refrigerant, yes the same one later blamed for the ozone hole when the patent went generic and everybody started making it. Dow and other companies funded the devil gas pogrom up through the 60s and then the oil companies flush with money picked up on it and started an anti technology cult to halt development of nuclear power and efficient space based solar power. Yes the world is getting a little warmer that it was 150 years ago, is this because if cars and industry, no it is not.

How Co2 really works

Well I have been looking for months for this core explanation of how Co2 works in the atmosphere. This is what I learned in school 50 years ago and why the current AGW hypotheses was so strange when proposed. Well it is strange all right because it is completely fictional, here is the true time tested way it really works! Read some of the reports covered on these links and you will know more than enough to reject most of the alarmist propaganda!

http://nov55.com/ntyg.html

http://nov55.com/gbwm.html

http://nov55.com/acd.html

Co2 is not the cause of warming it is a side effect of warming caused by the suns warming the oceans and warmer water can hold less Co2 in solution. Because the bio fuel industry has cut down so much tropical forest to plant oil palms and sugar cane there is no longer enough forest left to bank the excess Co2 until the oceans cool enough to absorb it again.

An interesting article on what is starting to become known in the popular press as yellow science in the same fashion as in earlier days yellow journalism caused many evils to sell a few more newspapers.

http://online.wsj.com/article/SB121433436381900681...

First most teachers confuse the students because they do not know the real answers so they provide the confusing political talking points they have been given to use. In 1850 the world was coming out of the little ice age where temperatures had been very low because of 4 periods of low sunspot activity that had occurred close together with only a couple of warming periods like our current one between them. There is still a lot of scientific debate as to whether we are in a true climate optimum or if this is only a short spike between minimums like the one that occurred between the Spoorer and Maunder minimums.

There isn't any evidence that CO2 is what caused the slight warming we experienced after coming out of the little ice age.

The biggest piece of evidence is the cooling upper atmosphere. You agree that the planet has warmed, so something has to have caused it. If it were due to the sun, all the layers of the atmosphere would warm. If it were due to an increased greenhouse effect, we would expect the upper atmosphere to cool. The simplified explanation is because more heat is trapped in the lower atmosphere. And indeed the upper atmosphere is cooling just as expected.

There's also the fact that global climate models show that CO2 can explain the recent warming, but natural factors cannot. But I suspect you won't trust climate models.

I've summarized the evidence in the link below.

lylyons can you stop linking every single website that mentions AGW in your favor here!

I'm a skeptic and I support you, I've asked similar questions and turned up arguements and dead ends....theres no end to it. They won't consider a skeptics view seriously, they'll think were just one of those conspiracists who are mislead and misguided. Their going to keep their beliefs, and we are goign to keep ours. No progress will be made my friend.

yes you need help , but if you cant find evidence its because you are reading with a prejudiced eye. most scientists when investigating a problem havent already decided what doesnt cause the problem. al gores movie has plenty of evidence you just dont want to see it. the evidence

There is no evidence..... PERIOD.