That is what is supposed to happen! That is what the polar ice caps do. They bounce the suns rays back into space, if they do not, you get a Warming effect. The Polar Ice caps act as a mirror. Much less of this has been happening given that the polar ice caps are melting. This is one of the basic principals in understanding Global Warming and I guess you failed. It is the green house gasses that are trapping this air in our atmosphere that is the problem. Here is a chart that explains that.
Pretty simple if you take the time to educate yourself on what is going on. I suggest watching "An Inconvenient Truth," which explains all this in easy to understand terms.
This is just one side to the approach of reducing the effects of Global Warming and I think it is a great idea.
By replacing dark-colored roofs and pavement with reflective alternatives, we can offset 44 metric gigatons of greenhouse emissions annually.
Also he asked for flat roofs to be painted white.