An astrophysicist has come up with a solution to global warming: move the Earth 3 million miles further away from the sun.
Even if this could be done, wouldn’t we have to move it back once the problem is “fixed”?
Apparently neither you nor the Daily Mail headline writer read the article. The proposal is not to address global warming, it is to solve the problem of the Sun getting steadily hotter and making the Earth uninhabitable on a billion year timescale.
'And as we have a billion years for the move, this means we only need one fly-by from the asteroid every one thousand years.
‘Do this once every thousand years, and over a billion years we can move the Earth enough to keep its temperature constant while the sun brightens.’
I’ve calculated that you could also do it with a network of orbiting railguns that fire at least twice each revolution and so remain in the same place relative to the earth, but their projectiles would represent a momentum transfer outside the system. It would have to be a fairly large network firing fairly constantly, but it would also eventually get the job done. And you also have to make the projectiles move fast enough that they will leave the solar system or else you’ll be putting artificial meteorites in your path.
From where do you get the projectiles?
Buy the secret of a reactionless drive from passing Outsiders. It’s expensive, so we’ll have to pay them back in installments.
Paul Birch of the British Interplanetary Society came up with a very similar scheme about 30 years ago. His idea was to steer pellets of metallic asteroid material using magnetic fields, into orbits which add or subtract orbital velocity from the Earth (or any other planet).
This could work in theory, over the billion year timescale that Reimann mentioned, but would not be much use in the few decades and centuries that will see the Earth heated by anthropogenic global warming. If you want a high-tech solution to the global warming problem, you could try another of Birch’s ideas, a large solar sunshade balanced against gravity and light pressure, located between the Sun and the Earth.
The scientist also proposed a way to move boxlike things, possibly containing people, by balancing them on a series of sideways discs that are free to rotate.
The particular wheel of moving a planet with asteroid flybys has been invented a number of times before in science and science fiction. Here is one from 2001 (the year, not the movie):
I bet @Andy_L can rattle off more examples off the top of his head…
First one to come to mind is Niven’s World out of Time in which moving Earth becomes urgent enough to require action before mere millions of years have passed
Brin has a serious proposal for moving the Earth without asteroid flybys
I’ll move it for you. You guys just have to buy me dinner. 
I would really like to know how they think they are going to apply a force to the Earth to change it’s orbit without creating so much heat that it won’t itself warm up the planet.
…And then declare the extra time gained Robot Party Week?
Probably cheaper to arrange for a a major impact with the Sun that’ll break off just the right size chunk of it and send that out into interstellar space, leaving a smaller safer Sun here for us.
Yeah, right! 
Can’t we just crank up all our A/C units and leave the windows open? I’m not a fan of General Motors Junk, but they do have Kick-Ass Air!
A billion years makes an installment plan very feasible.
I read on twitter that Bill Gates wants to put up a huge tarp, which would be less expensive.
And if we owe them enough money, then they’ll have a vested interest in preserving our existence! Win-win!
You do it v e r y s l o w l y.
The main effect would be tidal, whether you use Brin’s Moon L2 tether method or Birch’s asteroid method. Try to change the Earth’s orbit too rapidly, and you might get a few extreme tides, but that would be a signal to slow down.