-ponyville floods with a huge wave- Pinkie: JACK BLACK?! Twilight: NO PINKIE ITS- -SPLASH- Twilight: -swims up gasping for air- Guys?! GUYS?! -looks around freaked out- Pinkie: -splashes up gasping for air next to Twilight- Twilight: Thank god your ok! Pinkie: -points at the water- LOOK TWILIGHT JACK BLACK! Twilight: -chuckles- No Pinkie it's- -looks at the thing shes pointing at Jack Black Sea Pony: Sup Twilight:-dreams crushed forever- ;~;
Oh, it would cause more than tidal problems. Such a major gravitational shift would also cause massive earthquakes and alter the orbit of the earth. Best case scenario? Cataclysms abound wiping out a majority of life. Worst case scenario? The planets orbital path alters, escapes the sun's habitable zone where liquid water and reasonable gravity can exist, and all life is lost.
...wait, what am i saying? Since when is pony extinction a "Worst case scenario?"