The phrase "mounting evidence" means that there is an increasing amount of proof or supporting information that strengthens a certain claim or belief. Full definition
The society published a position statement last month calling for the limits because of mounting evidence of the effects of marijuana on the developing brain. (theglobeandmail.com)
Now mounting evidence suggests that many of these defective genes fall along a brain pathway where key neural connections develop. (scientificamerican.com)
State of the arts: Despite mounting evidence of its role in student achievement, arts education is disappearing in the schools that need it most. (citejournal.org)