Some scientists are of opinion that global climatic changesand increased average temperature of the earth is not caused by human activities, but by natural causes like sunspot cycle and change in the axis or tilt of the earth.more than that, asteroid collisions spews out more dust particles in to the atmosphere than one can imagine. The amount of sulfur oxides, which is belched out of massive volcanic eruptions, comes more than that produced by any human activity. The explosions on the sun’s surface produces intense heat energy, when this heat radiation reach the earth’s surface it can cause increased temperature within the earth’s atmosphere.
