Are things bad with the environment or is it blown out of proportion?

Here we are pumping out enormous amounts of pollution from our factories, vehicles and power plants.  Due to the carbon dioxide levels the human race is creating, we are being told that these gasses are causing the planet to heat up.  The heating up of the planet is causing the melting of the ice caps, and changes weather patterns.

Now we are not talking about 15 degrees a year increases, but the increases are measurable.  Some people say this is nothing to worry about and it is just a fluctuation which the planet cycles through.  As for the Ice caps, they have been melting for a long time, well before man had factories and cars.

On the other hand we are being told if we do not change our habits now, we will not have a habitable planet in a couple of decades.  We will have food shortages, un-breathable air that he been polluted and no way to correct the problem once the damage is done.

So the question is this, are scientists making global warming into a bigger deal than it really is?  Perhaps they are crying Chicken Little, or perhaps they really do know what is best.