eScience authority certificates
Although browsers (like Firefox etc) know about many commercial issuers of certificates, they do not necessarily know about or automatically trust a certificate issued by the UK eScience Certificate Authority, which this web-site makes use of when in secure (https) mode. To avoid having to make a security exception in your browser for this web site, it is better to pull the UK e-Science Certification Authority's own certificates into your browser using
Your browser will then trust any certificate issued by the UK eScience authority in the same way as it trusts certificates issued by well-known commercial authorities. To import the certificates, for Firefox go to the 'burger'/3-line button in the top right and do 'Options -> Privacy & Security -> View Certificates -> Authorities -> Import'. For Chrome, go to the same button in the top right and then select 'Settings -> Security -> Manage Certificates -> Trusted Root Certification Authorities/Intermediate Certification Authorities -> Import'. Note that the Root cert goes in the Root section and the eScience 2B cert goes in the Intermediate section. If you are on Mac, you will need to add these to KeyChain and make sure you set the trust settings appropriately.
With the authority certificates installed, your browser will trust this web-site even when the certificate is updated. Note however that to access group-restricted areas of this web-site, this web-server has to trust you, which will require you to have your user certificate in your browser, and the credentials of that certificate to be on a list for known group members, maintained by the web-site administrator.