Robinson Meyer in The Atlantic:

In 600 years, scholars translating books from before the 21st century will know that “noon” needs to be “1 p.m.”

And the opportunity cost for ignoring Leap Seconds…

Reddit, LinkedIn, and Yelp all suffered issues related to the last leap second in 2012. And, more seriously, computer booking systems used by Qantas Airlines all struggled, delaying flights by hours.

In some cases, it is impossible to update systems before the next leap second arrives. Matsakis spoke of a Switzerland power company whose backup systems only turn on when needed—otherwise, they sit disconnected from the network. When they were activated in a test after the last leap second, they crashed.

Had they been needed at the time, Matsakis said, parts of the country would have suffered a blackout.