The earth today is about 40 degrees warmer than it would be if we had no greenhouse gases at all. We know very well that greenhouses gases warm the earth, so it is a good bet that additional greenhouse gases will warm the earth even further. One of the most difficult problems that we have in predicting future climate is that predicting local climate is very difficult yet people live at local and regional scales. The raising of sea level over the next few centuries will also be very costly in both money and lives, particularly in poor countries. And it is poor countries that will suffer the most with any climate change because they have less resources to adapt.
Greenhouse gases are the key.
Like solar, wind, hydro, bio-mass, hydrogen, etc. The challenge is in changing from a energy structure which is built around big power plants that burn f ossil fuels to generating power more locally, solar works better this way for example. Personally, I think you can choose to use energy more wisely yourself and make a difference. More fuel efficient cars, for example or even very simple actions like desi gning your home to take advantage of passive solar energy. Put the windows on the south side.