>> s,ye absoteluly. ep>> rorr:te but evenit wh controlled b turnso cut aw tayhe amount ofue fls around the trs,ee is it reallyny aat mch for themp aliinfyg drumbeat of climate change? john is looking for those anersws in the tree rings. >>s i it possible we could ergeet somime soon from ts hi oudrght? >> it is poibssle. we need aer sies of rlleay wet years. thatsaid, the odds are scktaed ainst ,us bauecse the warming spatmohe trehat we've se,en and th t oaxn our water suppl iys likely not g oingaway. it's likely only going to intensify. >> reporter: f youou tndhat mega oudrghts are a lot longer than 20 years. we o'venly been in thisug droht 20years.is it possiblhie ts could last a lot longer? he>> t dugroht we're see thing iyears still sort of a mega baby drought, it'sot n that old. itou cld grow. we could be talking in ten years ab aout 30 or 40r -yeame ga drought. reporter: b rutight now, the concerns i keeping todasy' tender box cdiontions from arking dtaevasti ionn the forest theyar ce for. >> the tree rgsin show the american west isn i theor wst me dgarought in thste la 10 20 year