This is the Festival of Creation in Christ: creation given through Christ, reconciled in Christ, and destined in Christ for freedom and glory.
General Synod last month approved a new festival to be observed on the first Sunday of September every year. It launches the season of creation that runs until 4 October. We are encouraged to begin the observance of the Festival of Creation in Christ starting this year, on Sunday 6 September.
It provides propers to be used with the service of Holy Communion, lectionary readings, and responses for the gospel canticles at Morning and Evening Prayer. It should be fairly straightforward to substitute these propers for whatever other ones that had been planned to be used. Potentially less straightforward is preparing sermons and prayers on the theme. However, many parishes will have been planning worship for this Sunday as part of Creationtide anyway.
You can find out more about the detail of the new festival, together with the liturgical provision (in the annex of the document). The Second edition of A Time for Creation includes the authorised texts and lectionary for the Festival of Christ in Creation - together with a Commentary by the Liturgical Commission on the new provisions and an updated introduction. (Scroll down to access the full text.)
In addition to many other resources generally for worship in the Season of Creation, these two links give very helpful historical and theological background to the new Festival, the rationale for its Christological title and the meaning of “Creation in Christ”: