We wish that were true! How wonderful it would be if the nightmare of climate change was just a bad dream, or even a massive conspiracy. What a relief it would be to be able to plan for a stable future, to live each day without the painful knowledge of climate change. So we understand the appeal of this perspective, and share the desire to doubt or deny the existence of climate change. Unfortunately climate change is very real, and it is our duty to face that terrifying reality.
There is a scientific consensus that fossil fuel emissions are causing climate change. It is settled science, like the fact that the earth orbits the sun or smoking cigarettes can cause cancer.
The only reason there is a sense of uncertainty is because fossil fuel companies have spent hundreds of millions of dollars in a misinformation campaign, creating "foundations" and "institutes" to act as though the science were in doubt. Tobacco companies did the same thing when it became clear that their product caused cancer. They paid scientists to gin up doubt in order to protect their profits. Of course, part of us wants to believe the doubt that fossil fuel companies sell, because it is comforting to us.
For a comprehensive list of "scientific" denier arguments and myths about climate change, see Skeptical Science's Argument Page. They are a great resource if you are talking with someone who is mired in denialist arguments such as, "It's a natural cycle," "There hasn't been global warming for 15 years," or, "In the 1970s, global cooling was predicted."
However—remember that many people who deny the existence of climate change do so because they are scared, not because they actually believe the myths. Overly intellectual or scientific arguments might not be the best way to go. Instead, you could try questions such as, "Well, what if climate change was real and did threaten civilization? Then it would make sense to mobilize, right?"
For a great source of scientific information and arguments against denialist claims, see Skeptical Science.