Which activity is most likely a result of a sudden, unexpected change in the environment?

I think that carbon dioxide/pollution could be a massive change in the environment. You can find more information here
http://www.theworldcounts.com/stories/How-Pollution-Affects-the-Environment

The soviet union beat the us to the first successful launch, with the october 4, 1957, orbiting of sputnik 1, and later beat the us to have the first human in earth orbit, yuri gagarin, on april 12, 1961. the "race" peaked with the july 20, 1969, us landing of the first humans on the moon with apollo 11