I like these compositions with a solitary tree down in front of these giant dunes. I would never have spotted the climbers on the dune ridge if you hadn't mentioned they were up there. They really add a sense of scale to the massive size of these dunes.
There is an issue with Uploading Photos (attachjments). I am not sure what the problem is, and I am looking into it. You can still try to Create your Threads and Upload your Photos, but it is hanging up during the Upload.