So far, we know that there are at least two "catastrophic events":
<li>A meteor hits the planet (approximately after a month)</li>
<li>Collapse of the ecosystem (caused by the players)</li>
Simply put: I believe <b>such events should not be game stoppers.</b> The game shouldn't "end" once it's uninhabitable because it can teach a lesson that way.
Instead of showing a cutscene and displaying "You tried your best but didn't succeed, good luck next time!" before rolling the credits, players should be able to experience the catastrophe. Let the meteor hit and have them experience the slow death of flora and fauna. This offers a new, interesting aspect on the social component: The struggle for resources (and probably power) in a post-apocalyptic world. While this might not be the main message of Eco, I think struggling to survive in an increasingly hostile environment would reinforce the survival aspect as well as that feeling that everything was better before (i.e. put bluntly, to induce guilt). On top of that, all this would be optional: Players could leave whenever they want and a community might decide that once they failed to save the planet, they abandon it. The game would not necessarily need any additional content for it either.
By letting players continue (or start) playing on such servers, you let them experience their failure at first hand. This could easily serve as a demonstration tool for future or other servers, in the sense of "Well, if we don't get this project done by the end of the week, you can check out our first server to see what it's gonna look like".
On top of that, I think the events should have varying degrees of devastation. Of course that's not possible for some (you can't have a slightly collapsed ecosystem for example), but others like the meteor would work great. I'm thinking of something like increasingly random disasters: The meteor might pass your planet after a month, but won't hit. A few small to medium meteors that are dragged in its tail however do. They're no threat to the global environment, but might cause havoc in a smaller area. This would both warn the player ("Uh, so these meteors are a real threat... I suppose we should invest astronomy?" which could lead to "Well, our astronomers found out the meteor's due to strike our planet in 14 days.") and show them what happens if they fail to prevent it.
Other events that could work this way that I can think of on top of my head would be (super-)volcanoes (maybe with earthquakes/geysers as harbingers) or floods, depending on how water will be implemented.
Of course, these events could be a curse and a blessing. Maybe the meteor's impact site is now rich in minerals, or the volcano/flood has fertilized the soil. However, whether there still is a community that can profit from these blessings would entirely be based on the preparations for the catastrophe as well as whatever happened during it.
I think that it would make for a vastly more interesting game where you are allowed to let such catastrophes happens - as long as you deal with the fallout accordingly. What do you guys think about that?