>Perhaps the heat reflected by the clouds remains trapped in the atmosphere or is mainly absorbed by the clouds anyway.
The clouds that form in the lower part of the atmosphere do shield the surface of the earth from solar radiation. However, the clouds higher up, reflect and radiated heat from the Earth back to the Earth. But to rely on this balancing process when Global Warming increases, is a rather capricious thing to do. The behaviour of clouds is just too unpredictable to decide whether they will cool or heat the Earth during Global Warming. If the temperature were to increase, the low lying clouds (which shield radiation) may actually evaporate into higher flying clouds (which trap heat radiation). If this were to happen, it will actually add to the effect of Global Warming. It could happen the other way and reduce Global Warming, you never know. But yeah, as I said, we don't know enough about clouds to make a certain decision about how they will react to temperature rise.