Quiz #5 (Two Questions, No Answers)

Reuters reports:

Levels of climate-warming methane -- a greenhouse gas 25 times as potent as carbon dioxide -- rose abruptly in Earth's atmosphere last year, and scientists who reported the change don't know why it occurred. . . "The thing that's really surprising is that it's coming after this period of very level emissions," said Matthew Rigby of the Massachusetts Institute of Technology. "The worry is that we just don't understand the methane cycle very well." . . . The rise in 2007 was about 10 parts per billion over the course of a year, a real jump for such a short period of time.

Engineer Tom Nelson asks:

If the science is so settled, why are we constantly reading about scientists claiming to be stunned by new data?

To which I add:

If greenhouse gas emissions rose dramatically but temperatures fell equally dramatically in 2007, why are we constantly reading about scientists certain GHG emissions cause warming?

Previous posts in the series here, here and here.