The Queen has sent her "warmest good wishes" to hundreds of bishops attending the Lambeth Conference in Canterbury, Kent.
In her message, the Queen, who is the Supreme Governor of the Church of England, said that the conference was being convened at a time of "great need for the love of God - both in word and deed" as the world emerges from the pandemic.
She also said it was "a period of immense challenge for bishops, clergy and lay people around the world, with many of you serving in places of suffering, conflict and trauma".
"It is of comfort to me that you do so in the strength of God," she said.
In the message, the Queen expressed her appreciation for the conference's focus on climate change.
"We also live in a time when the effects of climate change are threatening the lives and livelihoods of many people and communities, not least the poorest and those less able to adapt and adjust," she said.
Today, the bishops are at the Archbishop of Canterbury's official London residence, Lambeth Palace, for a day centred on the environment and sustainable development. This will include the launch of the Anglican Communion Forest.
"I was interested to learn that the focus of your programme at Lambeth Palace today is reflection and dialogue on the theme of the environment, a cause close to the heart of my late husband, and carried on by The Prince of Wales and The Duke of Cambridge," the message continued.
The Queen concluded by reflecting on her own Christian faith.
"Throughout my life, the message and teachings of Christ have been my guide and in them I find hope," she said.
"It is my heartfelt prayer that you will continue to be sustained by your faith in times of trial and encouraged by hope at times of despair."