The phrase "demonstrable progress" means showing clear and undeniable evidence of making significant or noticeable improvements or advancements in something. Full definition
[4] Article 3.2 of the Kyoto Protocol demands that each Annex I country «shall by 2005 have made demonstrable progress in achieving its commitments under this Protocol». (foeeurope.org)
The ultimate test here is if we all focus on just a few things, deeply implement them, and analyze and learn together where it is and is not working, we can make demonstrable progress in reasonable time. (advanc-ed.org)
Unfortunately, without demonstrable progress in teh coming months, the movement is in danger of becoming a side - note — full of sound and fury but signifying nothing. (religion.blogs.cnn.com)