Tried to stay away from "climate change". What has happened is that one in 500 year storm/flooding events are happening way more than expected. If those are rare once every 500 year floods then having one per year for 2 straight years as just happened before Harvey has a probality of happening of 4 billionths. If you add Harvey then divide 4 billionths by 500 if it is a 500 year event or by 1000 if it is a 1000 year event as some are saying. It is very unlikely that those Flood/storm events are 500 year events and maybe more like one every 10 or 20 year events-- flooding and big storms are happening more often.