root@sclrdev:/home/sclr/certs/FreshCerts# curl --ftp-ssl --verbose ftp://{abc}/ -u trup:trup --cacert /etc/ssl/certs/ca-certificates.crt * About to connect() to {abc
On windows I was having this problem. Curl was installed by mysysgit, so downloading and installing the newest version fixed my issue.
Otherwise these are decent instructions on how to update your CA cert that you could try.