Not really an answer to the central ecosystem/climate question, but rather something about physics: the change will severly alter the orbit if not happening magically instantaneous and momentum-free. In any case it will require gigantic amounts of energy.

But what's really important to make this at least plausible is that this world is not going to slow down in its track, stop and then start up again in the other direction. This would make it crash into the Sun long before the stop. Instead, the orbit's so called inclination must (slowly) shift by 180° into a retrograde orbit. So it will steadily climb or dive from its orbit with respect to the solar system's main plane.

So over the course of the year, the sun is going to traverse other constellations until it arrives in the traditional ones again but will loop through them the other way around.

Another thing is that the planet will be barreling down the orbital highway the "wrong" way. Almost all of the stuff in a solar system goes around in the same direction, and many orbits are shared by several objects. So after your change, you'll have a much higher chance for hitting all this stuff coming up heads-on, until the planet has cleared up its path. Your average crash will be of much higher energy, too, because the relative speeds will be much higher.

Ok, this last point is even highly relevant to ecosystems and climate.

Not really an answer to the central ecosystem/climate question, but rather something about physics: the change will severely alter the orbit if not happening magically, instantaneous and momentum-free. In any case, it will require gigantic amounts of energy.

But what's really important to make this at least plausible is that this world is not going to slow down in its tracks, stop, and then start up again in the other direction. This would make it crash into the Sun long before the stop. Instead, the orbit's so called inclination must (slowly) shift by 180° into a retrograde orbit. So it will steadily climb or dive from its orbit with respect to the solar system's main plane.

So, over the course of the year, the sun is going to traverse other constellations until it arrives in the traditional ones again but will loop through them the other way around.

Another thing is that the planet will be barreling down the orbital highway the "wrong" way. Almost all of the stuff in a solar system goes around in the same direction, and many orbits are shared by several objects. So after your change, you'll have a much higher chance for hitting all this stuff coming up heads-on, until the planet has cleared up its path. Your average crash will be of much higher energy, too, because the relative speeds will be much higher.

Ok, this last point is even highly relevant to ecosystems and climate.

Not really an answer to the central ecosystem/climate question, but rather something about physics: the change will severly alter the orbit if not happening magically instantaneous and momentum-free. In any case it will require gigantic amounts of energy.

But what's really important to make this at least plausible is that this world is not going to slow down in its track, stop and then start up again in the other direction. This would make it crash into the Sun long before the stop. Instead, the orbit's so called inclination must (slowly) shift by 180° into a retrograde orbit. So it will steadily climb or dive from its orbit with respect to the solar system's main plane.

So over the course of the year, the sun is going to traverse other constellations until it arrives in the traditional ones again but will loop through them the other way around. Another thing is that the planet will be barreling down the orbital highway the "wrong" way. Almost all of the stuff in a solar system goes around in the same direction, and many orbits are shared by several objects. So after your change, you'll have a much higher chance for hitting all this stuff coming up heads-on, until the planet has cleared up its path. Your average crash will be of much higher energy, too, because the relative speeds will be much higher. Ok, this is even highly relevant to ecosystems and climate.

Not really an answer to the central ecosystem/climate question, but rather something about physics: the change will severly alter the orbit if not happening magically instantaneous and momentum-free. In any case it will require gigantic amounts of energy.

But what's really important to make this at least plausible is that this world is not going to slow down in its track, stop and then start up again in the other direction. This would make it crash into the Sun long before the stop. Instead, the orbit's so called inclination must (slowly) shift by 180° into a retrograde orbit. So it will steadily climb or dive from its orbit with respect to the solar system's main plane.

So over the course of the year, the sun is going to traverse other constellations until it arrives in the traditional ones again but will loop through them the other way around.

Another thing is that the planet will be barreling down the orbital highway the "wrong" way. Almost all of the stuff in a solar system goes around in the same direction, and many orbits are shared by several objects. So after your change, you'll have a much higher chance for hitting all this stuff coming up heads-on, until the planet has cleared up its path. Your average crash will be of much higher energy, too, because the relative speeds will be much higher. 

Ok, this last point is even highly relevant to ecosystems and climate.