Well, I start to check the basics here. It seems you do not contest than that there is a climatic change ongoing. Right?

You make a point: What to do?

Thats where discussing the reasons come in. And factually we have there several theories that try to explain it. Some of them are supported by a large majority.

Some are pretty for sure. Like for example that the rise in CO2 is human made to the largest share. No sane person would seriously contest this. Its furthermore proven that CO2 effects the warming.

How much? The majority of scientist says signficantly. But of course as its very hard to prove that in a water tight manner (actually that will not be possible before its too late) you always will get the counter studies of those who dont like the conclusions one would have to take out of that.