It's not just ash which is under threat, climate change is on the move and causing problems all over the world.
http://www.abc.net.au/catalyst/stories/3488105.htm
I guess this has happened throughout the history of the planet. Maybe trees will survive as those resistant to climate change and disease are favoured. Shame it all takes such a long time. I think ours and the following generations will find the ash crisis just the tip of the iceberg