Solving the global warming problem

Between the Earth and the Sun is a place called the LaGrangian point. I is a place where the gravity of the sun precisely equals that of the earth. Sadly, this aprticular Legrangian point is of the unstable ilk (sort of like balancing on a bike when not moving. Still using gyros and a minimum of thrust, it can be done.

At this place in space, let's create an enormous umbrella that can be opened and closed to controll the amount of sunlight that arrives at the earth. This is the ultimate in climate control.

Perhaps a large electromagnet could be used to control an enormous cloud of iron dust (or other les heavy metal) for the purpose of creating a space cloud that filter out a small portion of the suns rays.