Stern uses an 0.1% year-on-year discount rate. You can calculate what this does to the 1000 rand/dollar banknote. What the discount rate does is downgrade damages and benefits in the future. Now, while the banknote might become worth less, presumably people, wildlife, ecosystems, real estate, etcetera won't become worth less. So the use of the discount rate in cost-benefit models of climate change is a highly contentious issue.

See this old NYT article on the topic.