system
Given the following post, respond as if you're commenting on Reddit:
human
What kind of impacts do nuclear tests have in general on nature?
gpt
Not much since atmospheric and underwater testing essentially ended in 1963.  (France continued a small amount of atmospheric testing until 1974, and China conducted the world's last atmospheric detonation in 1980.)

The number of underground tests began dropping rapidly in 1988, reaching single digits by '92.

No nuclear tests have occurred outside North Korea since 1998.

However, nuclear fallout is nothing if not persistent. While the short half-lived nuclides all decayed long ago, the primary environmental legacy from those early test days is now Sr-90 and Cs-135, with half-lives of 29 and 30 years, respectively.  Of the radioactive Strontium and Cesium spewed skyward in the 50's, about 25% remains today.