Another plot idea

Here's the idea:

For no apparent reason the trajectory of Earth’s orbit has been abruptly altered. Although the change was small, scientists have concluded that the resulting decay will be irreconcilable in about three months, resigning the planet to imminent destruction in a little more than 900 years.

Plot points:

1. How will humanity rally in the window of hope - the next few months?
2. How will humanity respond to the loss of hope after the next few months?
3. How can mankind be convinced to care for humans who are more than 100 generations in the future?
4. What weather changes might occur?
5. What economic impacts might occur?
6. What political changes might ensue?
7. Will there be a religious impact?
8. Will science be elevated as a better good in the search for a solution?
9. Will despair overwhelm the population?
10. Will mankind cherish Earth less?
11. Will environmentalism be as important?
12. Will space travel become a priority?
13. Would anything change?

Good tangents:

1. What caused the change in the trajectory?
2. Would the environmental changes excellerate the human incompatability of Earth?