Why Does It Matter if Global Warming is Man Made?

One thing I just don't get about the whole global warming thing is trying to determine whether it is natural or not. The implication is that if it is caused by humans than it is bad and needs to be stopped, but if it is not caused by humans then it is natural and can continue on its merry way.

I just don't get this. Shouldn't we instead look at whether global warming is good or bad for nature (or humans) and try and stop if it is bad, and continue if it is good?

Just because something is natural, doesn't make it good. Was the tsunami ok because it was natural? When a volcano errupts and wipes out cities and natures with lava and affects the atmosphere with soot, is that a good thing? What about earthquakes? Or, how about if a huge meteor is going to strike the earth. Should humans attempt to stop it? It would be a natural thing to allow it to strike, but something extremely damaging to life on earth.

If global warming is bad for life, but it was caused by termites munching or cows farting or changes in the amount of sunlight that hits the earth or some other natural cause, shouldn't we attempt to stop it?

So, I don't see why we are so hung up on proving that humans are causing this with the cars and the agriculture and the concrete.

One line of reasoning that I can undertand is if we can prove that the carbon dioxide emissions are causing it, then we can just stop emitting them and stop the problem. While that is one way to stop the problem, but it not at all clear that it would be the best. If cars are emitting lots of CO2, instead of telling people to drive less, maybe there would be a better and cheaper way of extracting the CO2 from the air. Maybe we start planting a lot more trees as a way to suck up the CO2. Or maybe we find a way to sequester all the CO2 in the ocean. Or maybe instead of dealing with the CO2, we find another way to cool the earth. Volcanos cool the earth after they errupt by blocking the sunrays with airborne particals. Maybe we go this route. The point is there are a lot of other possible ways to stop global warming. They should be evaluated on a cost/benefit basis. If using less fossil fuels is the best way to solve the problem, then lets do it. But, lets look at other possibilities as well.

So, lets drop the debate on whether humans are causing global warming, and try and figure out what its impact will be and then try and find the most cost effective way to stop it.