... and numerous ideas have been studied and proposed.  They include

1. A single concave fresnel lense 1000km's wide and a few mm thick placed at what is known as the L1 orbital point (where an object would rotate around the sun at the same rate as the earth).

2. A ring of earth-orbiting satelites, micro-space craft or particles.  They only need to orbit one small section (say the equator) and lessen the impact of the sun there to have a global affect.

3. Trillions of tiny lenses/screens only 60cm across, once again orbiting the sun at the L1 orbital point.

You're right about it being no joke.  It's no laughing matter and has been investigated by scientists quite seriously.  I'm sure there's other ideas as well, but those are the three I was familiar with and fortunately for me a quick google search brought up the third link which in it contained the first two as well making my job of finding them much easier.