The back ground trend is based on increased demand from population boom and better emerging economies. On top of this we see spike due to weather events, pests etc. It does look like the growing conditions have been very good, until just recently. If we get some poor crop condtions in major producing areas again next year back to back years commodity prices will spike an even greater amount. I would not count on back to back poor yields but the tie to population growth is their. No way to guess the weather.