I won't repeat the article from Scientific American; the author (Michael E Mann) says it better than I can. You can read it here. A key discussion in the article is how much global temperatures will rise if atmospheric CO2 doubles from the 280 ppm (parts per million) before industrialisation began to 560 ppm. His estimate: 3 degrees centigrade.
The first chart below from the article shows different estimates of how much the world will warm based on different lines of evidence.
The second chart shows how temperatures will rise depending on just how sensitive the world's climate is to rising CO2. In the article, the author points out that reducing aerosols (emitted along with CO2 by burning coal ) will cause global temps to rise. So ironically, even as China slashes its emissions of CO2 global temps will rise/
Disclaimer. After nearly 40 years managing money for some of the largest life offices and investment managers in the world, I think I have something to offer. These days I'm retired, and I can't by law give you advice. While I do make mistakes, I try hard to do my analysis thoroughly, and to make sure my data are correct (old habits die hard!) Also, don't ask me why I called it "Volewica". It's too late, now.
BTW, clicking on most charts will produce the original-sized, i.e., bigger version.