Humans cause climate changing

In response to my contention that the planet does not need humans in order for the climate to change, my opponent has simply stated that, it was 248 Million years ago, implying, I assume, that this is not relevant to today's climate. The problem with this statement is twofold. First of all, the Mesozoic Era ended in the late Cretaceous, which was 65 Million years ago as opposed to 248. That's considerably closer to modern time. Also, in the period closer to us, there was no Ice at The poles. [1] The second issue I have with this rebuttal is that the Mesozoic era is not the only example of pre-industrial age climate change. In fact, duing the last 2 billion years the earths climate has been fluctuating between a "hot house" and an "Ice House", clearly illustrated in the chart below: Taken from http://www.scotese.com... [2]In fact, If you look at the chart, you notice that, for a long period of time we have had a downwards trend in the climate of the earth. This is infact, the longest downward trend in recorded history. So we are actually long overdue for a warming earth, and when you look at the big picture, the logical thing for the earth is for it to keep warming as it has in the past. Next we move on to my opponents next point, about humans actually having deliberately influenced the weather. While at first it may seem like this is an insurmountable argument for man-made climate change, it is actually rather irrelevant. You see, what my opponent has failed to take into account is the difference between climate and weather. Climate is defined as: the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years. [3]So humans deciding that they do not want it to rain tomorrow is not an example of climate change, it is an example of weather change. Even a nuclear explosion, which will change the weather for perhaps a few months, is still not climate change, as it has not had a sustained, long term affect on the climate. The very article that Pro provides to substantiate his claim that CO2 emissions by humans are the leading cause of climate chanche clearly lists water vapour as the most common greenhouse gas found in the atmosphere. And how does water vapour get into the atmosphere? By evaporation powered by the sun, not by humans. And while I will conceded that humans are the No.1 producer of CO2 in the world, as I said in my previous argument, methane, a common natural gas, is actually more effective at trapping head than Carbon Dioxide. A single volcano, such as Mount Eyjafjoell in Iceland, can produce around 300,000 tonnes of CO2 per day. This places the one volcano alone above countries such as Austria, Portugal and Ireland in terms of emmisions. In conclusion I have clearly demonstrated how the earths climate can easily change, and has been changing, without any help from man, how many made weather is not climate change and how human CO2 emission is not such a big problem as we think it is. The resolution is negated. [1] http://www.enchantedlearning.com... [2] http://www.scotese.com...[3] http://dictionary.reference.com...