For over six years, the Google Earth API has enabled countless developers to build 3D mapping applications in the browser. Those days are over as Google announced on its developer blog that the API is deprecated and will officially retire December 12th, 2015.
The Google Earth API is built on the NPAPI plugin framework which Chrome and Firefox no longer support due to security reasons. Over the past six years, the API has experienced dwindling support across multiple platforms, especially on mobile. It’s worth noting that Google Earth is not going away; only its API is being retired.
A quick search of the WordPress plugin directory for Google Earth shows at least three pages of results. However, several of the plugins look like they use Google Maps instead of Google Earth. If using an external API, most authors put the information in the plugin’s description. If you’re using a plugin that uses the API, please get in touch with the author and let them know it’s no longer supported.