Medical experts say small amounts of carbon monoxide over a long period of time can greatly harm an unborn baby.

VOA: special.2010.02.02

So,to get a sense of what the regional moisture patterns have been, dryness and wetness over such a long period of time in great detail, I would call it a kind of victory for paleoclimate science."

VOA: special.2010.05.25

"Any substantial eruption of a volcano has a potential to do that over a short period of time.

VOA: standard.2010.04.15