Climate change is always happening. If you look at 25,000 years ago, earth was covered in sheets of ice and the sea levels were hundreds of feet lower. In Roman times, the climate was warmer and was referred to as the climate optimum. Then in the 1800's the climate cooled and was in a little ice age. in the 1900's, the climate again warmed. So asking why climate change is real is an easy question, because the climate is always changing.

The question I think you are asking is, why is man made climate change real? For this, the answer is again fairly easy. There is very little man made climate change. Sure man has contributed some CO2 to the atmosphere, and that could add at most about 1.5 degrees of warming for a doubling of CO2. However, the "climate change" you see people worrying about are only in the minds of the modelers. "scientist" create models which shows how we are going to kill the planet. Then, the actual scientific measurements come in and we are no where near where they predicted, and no scientific evidence to back up the dire predictions. You would think the modelers would admit defieat, but no, they double down and make idiotic claims like "We have 500 days to address Climate Change" or similar nonsensical statements. So if you are trying to have evidence that man is the primary driver, then you are out of luck. If you need to show that climate does change, here are some sites:

Simply studying this graph will answer is there climate change.

http://en.wikipedia.org/wiki/File:Ice_Ag...

The evidence of climate chane is in the glaciers

http://www.museum.state.il.us/exhibits/i...

You might ignore the global warming deniers around here, and look at the reputable organizations.

http://en.wikipedia.org/wiki/Global_warm...

"The finding that the climate has warmed in recent decades and that human activities are already contributing adversely to global climate change has been endorsed by every national science academy that has issued a statement on climate change, including the science academies of all of the major industrialized countries."

https://www.google.com/#q=scientific+org...

https://www.google.com/#q=universities+g...

Let me know if there is still any question at all in your mind about what's happening with global warming.

Compare those references to posters around here.

That should give you an idea who you should believe.

Once you think that maybe global warming is real, you might consider:

http://www.rkm.com.au/ANIMATIONS/carbon-... <== here's the physics.

http://upload.wikimedia.org/wikipedia/co... <== Note that CO2 intercepts a different wavelength than water. In addition, as CO2 warms the oceans, more water evaporates, increasing it's effectiveness.

http://www.school-for-champions.com/scie... <== melting of the Siberian tundra is a very serious problem.

http://fora.tv/2009/08/18/A_REALLY_Incon... <== This is an hour long, but is very good.

Climate change and Global warming are two different things.

Climate change is real because there are changes in the climate over time, however this doesnt mean global warming could be true.

It is real in the sense that adding more CO2 will cause a very small amount of warming, it is not real in the sense that it is dangerous or catastrophic.