The Greenhouse Effect is a natural phenomenon that baffled the greatest minds of the 19th Century. The influence of the atmosphere on surface temperature was first considered by Fourier in ~1820 and he determined that the surface temperature on earth should be much lower than it actually is. He concluded that the atmosphere must, therefore, act like a blanket. We now know that this blanket-like behaviour is due to quantum phenomenon (see my post on microwave ovens below) – this is The Greenhouse Effect and keeps the planet's surface temperature at ~25 degrees Celsius, rather than around 6 degrees as Fourier would have expected. So without The Greenhouse Effect things would be very different here on the 3rd rock!
Now, Climate Change and Global Warming are occurring due to The Enhanced Greenhouse Effect, that is, the impact that elevated levels of greenhouse gas emissions from anthropogenic activity are having on the surface temperature. So the question that needs to be addressed is how can the Enhanced Greenhouse Effect be mitigated? The answer is simple in concept but much more difficult in practice: decrease the rate of emission and/or increase the rate of absorption of the gases. If the rate of absorption is greater than that of emission then atmospheric concentrations will fall – however, stabilising the rates will only serve to keep the concentrations rising linearly as oppose to exponentially! This last point is subtle, but very important yet seems to be so often overlooked (Peter Senge has written a great synopsis on this in his book The Necessary Revolution, which is well worth a read!).
So the Greenhouse Effect supports life on earth. The Enhanced Greenhouse Effect is what we as a society need to combat if Global Warming is to be mitigated. The problem is that requires a paradigm shift in how as a society we function.