Has someone ever asked you an important and complicated question that you’d like to answer, but you have a frustratingly brief time to respond?  Your time-limited response is called an elevator speech because you only have the amount of time it takes to go up or down a very few floors.  You’d start with the most succinct and encapsulating sentence, and then wrap with perhaps the most memorable.  Keep in mind that an average intelligent human can keep at most about six or seven things in short-term memory.  In a noisy or crowded elevator, little would be remembered unless carefully crafted. 

With regard to a question about the potential of an existential threat from climate change, this would be my elevator speech.  By my stopwatch it takes 54 seconds to cover these ideas.  I would hope that some of these points could be retained in the long-term memory of the person asking the question.

1. The climate changes in response to multiple factors beyond human control or even scientific understanding.
2. Climate change results from both natural and anthropogenic causes that vary in different environments.
3. Nothing humans can do on a local, national, or global scale can prevent the climate from changing.
4. A changing climate contributes to both beneficial and detrimental effects, but the relative benefits or detriments vary depending upon the location and species impacted.
5. Carbon dioxide contributes significantly to warming only when water vapor and other factors are of minimal impact or even absent.
6. Humans and other life must adapt to their ever-changing environment in order to survive and flourish.
7. Only the most adaptable life will persist on this dynamic planet revolving elliptically and precessing obliquely around a variable star in a chaotically complex galactic reality.