While I enjoyed the vast number of EP debunkers posting recently I'd like to point out a major error in the otherwise good job Mr Clements did. Impact experts believe long period comets represent roughly 25 % of the expected fatalities from impact. A long period comment is not one whose orbit that has been modified by Jupiter. Those are short period comments which are classed in with the asteriod portion of the threat as potentially detectable far in advance of impact. The estimate and explanation are readily available on the web in the various impact threat reports.

This is an important distinction, because it is part of a human survival justification for space exploration. The NEO part can be dealt with solely from Earth or Earth orbit with modest extensions of current technology. The LPC part can not.

Regards,
Mark