I didn't say that I don't want to explore and not know about it. If you have the answers in quantified terms, let the modelers know, and I'm sure that they'll give you enough credits for it. I don't know the reasons in the past; actually I don't know a lot and a lot of things, and so is in science. Every study and every conclusions drawn whether it be the experiment or model have many uncertainties. But do you think it'd be wise to be stubborn saying that I won't implement the conclusions unless all the uncertainties are explained and included? Regarding paleo data, we can't say whether it's CO2 or not because the data don't exist, and even if it exists, it's non-human activities. But today we can quantify emissions from human and non-human activities and can relate it to the quantity we observe today and can also quantify how much temperature increase it can cause or being caused by human or non-human activities. That is the basis for saying that human activities are the main reason behind it.