I noticed that the black seal around the rear window of my 2000 Volvo C70 coupe (coupe, not convertible) is crumbling and falling apart. The car is 25 years old, and I’m wondering if other people have experienced the same issue.

 

2001 C70. Was my fathers car and apparently he replaced the whole top the first time it happened.
I now have the car and it happened to me last summer (we had some high 30's C and it was sitting in the sun). About 1/2 came loose. I reglued it using some suction cup clamps I bought on Amazon.
It is holding so far...but it is just the start of summer....