Today, 45 people are beginning a mammoth walk from London to Paris, where the UN will meet on November 30 to begin its annual conference on climate change.

Those taking part in the 'Pilgrimage2Paris', organised by Tearfund, Christian Aid, CAFOD and the Church of England, hope to send a strong message to world leaders about the importance of agreeing to cut carbon emissions, and ensuring a better future for some of the poorest and most vulnerable communities across the globe.

Jean Leston, 62, has been training hard for weeks in preparationg for covering 200 miles over 17 days. Once just north of Paris, the walkers from London will join pilgrims from all over Europe and process into the capital together, where they will take part in a big church celebration as well as another climate march through Paris on November 29.

"Obviously, pilgrimages have deep resonance as a Christian," Jean told Christian Today.

"The journey of life is a pilgrimage, and we are aliens on this earth, travelling through toward our heavenly Father. The Pilgrimage2Paris shows that we are honouring God by praying with our feet and showing a real heart for serving him."

Climate change is a Christian issue, Jean said, because "it is probably the biggest threat to God's precious world" and those in developing countries are the worst affected. It's causing "droughts, floods, hunger, the spread of disease, conflict, and displacing people from their homes which means more refugees," she added. "For me, this pilgrimage is a way of living out my faith...We want to bring to the attention of our politicians that people of faith deeply care about this, and I'm willing to be a first-mover. I'm willing to step out, speak up, and say we need to change the way we live.

"It's simply not sustainable to keep burning fossil fuels and using resources as if we have three planets instead of one."

Christians, Jean continued, have always been at the forefront of tackling issues of injustice like apartheid and slavery, and this should be no different. "Climate change is the social movement of our time," she said. "Christians are called to be at the forefront of trying to change the world for the better; a world we can pass on to future generations unharmed, while honouring the call to be good stewards and obedient to God."

Jean said she "has always been kind of vaguely green, but a very, very light green", and it wasn't until she was on holiday in the Dordogne during the heatwave of 2003 – when more than 15,000 people died – that she realised the repercussions of climate change. Previously in the business sector, she's been working on environmental issues ever since.

At this year's Paris talks, activists hope that world leaders will take note and make ambitious, binding agreements that will bring climate justice to the world's poorest people.

"We want our political leaders to hear us, hear our faith voices saying that climate change is a moral issue, and we're calling on anyone involved in the negotiations to listen to their hearts, and not just be acting out of self-interest," Jean said.

"We are appealing to their hearts...and calling for those countries who have done the most to cause climate change to shoulder the greatest responsibility for cutting emissions, but also to move to a more sustainable path to economic development.

"As Christians we are all called to be obedient. The Bible is very clear that we are meant to protect the world God has made, a world where Jesus is the first-born of Creation and all things created for and through Him.

"There's a call for us to respect this world, and to try and restore it, not destroy it."