Christian Climate Action (CCA) is inviting people to take part in 40 days of action over Lent.
The campaign gets underway on Ash Wednesday on 26 February with a vigil outside Westminster Cathedral at midday that will then process to Westminster Abbey and Parliament Square.
Members of CCA are looking to the Catholic Church to follow the lead of the Church of England, which last week committed to net zero emissions by 2030.
In a symbolic act, priests will mark a cross on the foreheads of worshippers using fake crude oil instead of the traditional ash.
The CCA said that the use of oil was to symbolise human mortality but also “human frailty as we are currently losing the fight against the over consumption of fossil fuels”.
The 40 days of action will continue through Lent with a focus on “lament for the climate change and ecological crisis”, and prayers for leaders to take urgent action.