“John the denier” writes, “The only constant in nature is change”. That is absolutely and utterly wrong. That statement proves he and other deniers nothing about nature…or science. Newton’s first law of motion is: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. So, nothing changes unless acted upon by some force, whether internal or external. The climate of the earth will therefore remain static unless some force is either increasing heat to it , preventing heat from leaving at the same rate, or blocking heat. The average temperature of the earth can increase by the sun increasing heat production, or the orbit of the earth getting closer to the sun, or by heat being held in the atmosphere of earth by greenhouse gases. Reverse any of the vectors that cause heating, and the earth will cool.

The bottom line is this…the average temperature of the earth only changes in response to changing conditions. Conditions of the sun or earth’s orbit, or greenhouse gases, or ground reflectivity, or particulates in the atmosphere…it has to be something that is changing. Nature doesn’t change for no reason with no impetus. There is always something driving change. In this case, the driver is man’s use of fossil fuels and the increase in greenhouse gases that is driving the temperature of the earth higher.