Student or Learner
Gravest Challenge of the 21st Century May Be Disease - ABC News
"One of the real challenges we may face in the future is a new disease that sweeps across the planet -- because we're all so tightly connected together," says Thomas Homer Dixon, a political science professor and author of "The Upside of Down."
Why "says," not "said"?
Daruma, here's a way to think about this that might make it a bit more palatable:
In situations like this, when you read a report about something someone said or about an opinion or theory they have expressed, the emphasis is often not on the point in time when that person actually opened his mouth and uttered those words or picked up a pencil and wrote them, etc. The emphasis is on the fact that that's what they think; that's their stated opinion/theory/argument/whatever, and that fits quite well with present tense.