Ask questions immediately if you don't understand something. If you're in the front row and have been making eye contact, your instructor probably already knows by the look on your face that you don't understand something. A polite raising of your hand is all you need to do to indicate you've got a question.
In the annals of climatology, 2014 surpassed 2010 as the warmest year. The 10 warmest years have all occurred since 1997, a reflection of the relentless planetary warming that scientists say is a consequence of human activity and poses profound long-term risks to civilization and nature.