Do humans matter to climate?

From the simple model and its effects we can see that more detailed knowledge of how warming is occurring would be useful. One detail that is extremely useful to know is whether we have an effect on the trend.
We have no mechanism to influence the heat coming out from the earth, or arriving from the sun. We can and do affect every energy transfer mechanism from the earth's surface to the top of the atmosphere. Our agricultural practices determine the reflectivity of the land. We put enough particulates and aerosols into the air to cause more cooling than all but the most violent volcanic events. Our biggest effect, both relative to background levels and in absolute energy flow terms, is changing atmospheric infrared transmission through fossil fuel burning.
Scientists know with greater and greater precision how our influence on land albedo, atmosphere reflectivity, and greenhouse gasses affects our environment.
The simple model of an earth that freezes and thaws cyclicly, with the average ice line showing trends, combines with easily obtainable facts and figures to show that what the scientists are saying is reasonable. Our behavior is the major variable affecting world climate at this time, and changing our behavior will change the climate in knowable ways.