Pope Francis is reported to be wanting to galvanise Catholic Church's response to climate change.
Christiana Figueres, head of the UN's climate change secretariat, told an audience at St Paul's Cathedral that a new encyclical on the environment was forthcoming.
A Papal encyclical, a letter explaining the Catholic Church's views on a subject, sent out to the approximately 5,100 Catholic bishops worldwide, is an indication that a particular issue has become of great importance to the Church.
Ms Figueres expected that it would be released before the UN's climate change summit in Paris, in November and December of 2015.
However she was unsure if it would be released before the summit in September 2014 where UN Secretary General Ban Ki Moon is encouraging world leaders to draw up ambitious plans ahead of the 2015 summit.
Regardless of timing however, Ms Figueres was quoted in Business Green as saying that she believed that such an encyclical "could provide a strong signal to governments, cities, companies and citizens everywhere of the moral, ethical and responsibility dimensions of climate action".
Ms Figueres also praised the work of a number of faith groups actions on climate change in recent times, including the Church of England's review of its fossil fuel investments, UK Quakers divesting themselves of fossil fuel investments, and Multi-faith groups in Australia and North America who wrote to Pope Francis insisting that profiting from fossil fuels was immoral.
The Vatican has not offered any comment on the possibility of an encyclical on climate change. However in January, Pope Francis was reported to have begun drafting a text on ecology and the environment, which could become an encyclical.
Father Federico Lombardi, director of the Holy See Press Office, said to Vatican Radio that Pope Francis "intends to put particular emphasis on the theme of 'human ecology,' a phrase used by Pope Benedict to describe not only how people must defend and respect nature but how the nature of the person – masculine and feminine as created by God – must also be defended".
In Pope Benedict XVI's 2009 encyclical Caritas in Veritate – Charity in Truth, he speaks often of the importance of the environment to the Church: "The Church has a responsibility towards creation and she must assert this responsibility in the public sphere.
"In so doing, she must defend not only earth, water and air as gifts of creation that belong to everyone. She must above all protect mankind from self-destruction."
