How can I find the altmetrics for a specific paper?
Yes, you can use Altmetric's API to do that.
The URL is https://api.altmetric.com/v1/doi/ + DOI.
For example: https://api.altmetric.com/v1/doi/10.1016/j.gloenvcha.2020.102194.  However, the API is designed to be machine-readable (and not primarily human-readable), so you will only see a (possibly confusing) JSON-document which you may want to &quot;beautify&quot; using a JSON-Beautifier.
At the bottom of that JSON-document you see the element &quot;details-url&quot; which links to the actual page you probably want to see, i.e. http://www.altmetric.com/details.php?citation_id=93559766.
(For large-scale use of that API, you may need to request a key. See the Altmetric's API Documentation.)