World Day of Prayer for the Care of Creation - September 1st - "Show mercy to our common home"

In 2015, Pope Francis established September 1 as the annual World Day of Prayer for the Care of Creation in the Catholic Church. In doing so, he acknowledged his debt to the Ecumenical Patriarchate of Constantinople, which has observed September 1, the beginning of its liturgical year, as a similar day of prayer since 1989.

“As Christians we wish to contribute to resolving the ecological crisis which humanity is presently experiencing,” Pope Francis said in his August 2015 letter announcing the day of prayer. “In doing so, we must first rediscover in our own rich spiritual patrimony the deepest motivations for our concern for the care of creation.”

He added:

The annual World Day of Prayer for the Care of Creation will offer individual believers and communities a fitting opportunity to reaffirm their personal vocation to be stewards of creation, to thank God for the wonderful handiwork which he has entrusted to our care, and to implore his help for the protection of creation as well as his pardon for the sins committed against the world in which we live. The celebration of this Day, on the same date as the Orthodox Church, will be a valuable opportunity to bear witness to our growing communion with our Orthodox brothers and sisters.

The third World Day of Prayer for the Care of All Creation takes place today on 1 September 2017. Many local Church communities around the world also are preparing to mark Creation Time, which also begins today and continues until 4 October, the Feast of Saint Francis of Assisi. Creation Time celebrates the joy of creation and encourages awareness-raising initiatives to protect the natural environment.

A joint message was released this morning from Pope Francis and Ecumenical Patriarch Bartholomew, who for the first time are writing together on themes of the day, inviting all the faithful and men of good will to prayer and to reflect on how to live in a simple and solid manner, responsibly using earthly goods.

Pope Francis appeals for World Day of Prayer for Care of Creation - Vatican Radio

You can read more about the day here from the Irish bishops conference including resources and prayers.

Crux - Pope, Patriarch: ‘Cry of the earth’ and cry of the poor are one voice

Crux - Pope and Patriarch: A common declaration for a shared world - Rev. Dr. John Chryssavgis