Bitcoin isn't a threat but mining it using non-green energy contributes to the existing problem we call as global warming.
...if so will bitacoin and others be able to run forever or is this just an excuse to change the green field to red..
There are miners mixing the source of electricity for mining but it's still unclear how many percent is renewable and non-renewable. There is a Bitcoin Mining Council formed recently to address these issues so just wait for their report.
Green field to red? Are you talking about candles in trading?