The first Europeans landing on Easter Island in the Pacific wondered how on earth a few impoverished people on a treeless island could be linked with the amazing statues around the island, and why some were only part-finished or hardly started. Today we know that this was because the first inhabitants came to a lush island of palm trees and did well until someone had the idea of carving large stone into human forms: then everybody wanted one, and they cut down the trees to use to transport them, until one day there were no trees and little food and the population largely died out, and little was left behind except the wreckage of dreams.

 Today we celebrate Harvest – the goodness of God given to us in the living things of the world which sustain our life too: the sunshine, rain, food and water which we need to live. And we remember and respond to God's gifts by making gifts of our own to help sustain the lives of others.

Today is also a special day for creation. It's the feast day of St Francis, the saint with a particular affinity for the world and its creatures, who used to preach to the birds and sang of brother sun and sister moon. And it's also a Day of Prayer for Climate Change, called by all the Churches Together in Britain and Ireland, bringing together environmental representatives from churches including our very own eco-group, with organisations like Christian Aid and Tear Fund.

Why have a day of prayer? Because prayer changes things – and the world needs changing with regard to climate change. As a Christian leader involved in the day of prayer called Dave Bookless has said: "We need space to ask God for his perspective and intervention, to think about what our abuse of creation says about us, and to plead for a new vision of God's purposes for us in his world. I believe the Climate Change Day of Prayer is probably the most important initiative that Christians can be involved in during the lead up to the critical negotiations in Copenhagen.”  Copenhagen being the venue for the United Nations Summit for Climate Change in December, where crucial decisions will be taken – good or bad – which will affect millions of lives in the future.

You should have been given a leaflet when you came in with that quote and others on it, and ideas for prayer during the day. Please do take and use it, not only today but through the coming weeks too: because this is important.

When it was clear that today I would need to preach on climate change, my heart sank. Why? Because it seems worthy but dull: it's hard to make a sermon live, rather than being a worthy but dull-seeming lecture. So let's think a bit about what it means for someone we know. Revd Bello who was here from Sudan last week – do you meet him? - is one of up to 250 million Africans who won't have enough water to continue living in little more than 10 years. The current drought in Kenya used to happen once every 11 years – now it's becoming permanent; 20 million people in East Africa – that's equal to in in three people in Great Britain – are desperately searching for water and grazing for their animals before they all die. And that's now. E.g. Hassan in N. Kenya has sent his children away to abject poverty in a city slum and is walking 10 miles a day to get enough water to keep his small herd of animals alive, because he can't provide for both his animals and his children. And if no rain comes this autumn, he and his animals will die.

Ah we say, but climate change is happening and we can't do much about it. Or that it's all natural and not due to human beings at all. Or even like the ostrich that it's not really happening, despite all the scientific and practical evidence to the contrary. There are even people in America who say that because Jesus is coming back soon it's going to be awful whatever we do and so we should get as rich as we can while we can, and not care about the rest of the world.

Kiribati is a group of islands in the Pacific, about 1000 miles south of Hawaii, halfway between Australia and Mexico. In June 2008, the Kiribati president Anote Tong said that the country has reached "the point of no return"; he added: "To plan for the day when you no longer have a country is indeed painful but I think we have to do that." 100,000 people will lose their homes and become refugees, due to rising sea levels. Revd Baranite Kirata is a minister in Kiribati, and said: 'The storms and waves eat away our beaches and they will some day eat us. People whose houses are destroyed move inland, but we will end up fighting each other over land and food and water, until we all end up in the lagoon. It is now too late to do something for Kiribati and some other islands; but together we are the world, and it's not too late to do something for us all.'

God as well as St Francis has a lot to say about all this. There are three key strands that run through Scripture. The first is that we are God's stewards of the world: that at the very beginning God asks us to tend and care for the world and put it in order, for its well-being and the good of all. In other words, God treats us as gods with a small 'g', as God's right-hand people, with power over the world. The second strand is that instead of looking to God for guidance, we have trusted in our own power and gone after riches instead of being content with what the world gives, and so have destroyed the balance of God's creation. We have acted like the inhabitants of Easter Island: we all want nice cars and good houses and lots of things – but there's not enough to go round everyone...

 And the third strand is that there are positive ways to respond: on the one hand, to be content with what God gives us, not trying to heap up  riches that we can't keep anyway in the face of death; and on the other hand, to be hugely committed to work for God's justice in the world.

George Monbiot the environmentalist wrote in his book on climate change: 'My daughter was born while I was writing this book. This baby... changes everything. I'm no longer writing about what might happen to people somewhere in 30 years' time. I am writing about her... A world in which unrestrained climate change threatens the conditions which make human life possible, is the world into which she will grow. Global warming is no longer about abstract victims. Among them might be my child. Or yours.'

In today's gospel reading Jesus says: 'take no thought for the morrow'. But he doesn't mean that we should ignore what's happening in the world's weather. 'Seek first the kingdom of God and his righteousness' says Jesus, and then you'll have as much as you need for tomorrow.

Climate change is about justice. At the moment it impacts the lives of over 300m people; in 20 years' time that is estimated to double to over 600m, 10% of the world's population – most of them the poorest and least able to cope people in the world. But Britain will be one of the least affected countries. The rich will be OK while the poor go to the wall. And that's not God's justice or righteousness.

We can make a difference to God's world – we can be faithful stewards of what God has given us. Do we say that it's not worth caring for our neighbour because so many other people are nasty to each other that we might as well be too? No, of course not! So why should we say that it's not worth doing anything about the climate? Of course we can't bring about change single-handed; but we can make a difference by acting together. And that's why we should act and pray and work at being an eco-cathedral, and eco- people too.

Let me finish with a few examples about what's possible, just to encourage us in our prayers and action. Sweden has had a carbon tax since 1991, which was introduced alongside cutting income tax in half; although Sweden's economy has grown 44% since 1990, its carbon emissions have reduced by 9%.  Then there's the ozone layer. In 1989 there was an agreement to ban chemicals destroying ozone; and the ozone layer is now expected to recover by 2050. The city of Boulder has ignored America's refusal to ratify the Kyoto Protocol on carbon emissions, and has introduced its own carbon tax which will cut emissions to Kyoto levels by 2012. And in Bangladesh there has been a strategy to build flood defences and floating gardens which can survive flooding.

By God's grace there's plenty that we can do to help God redeem our world for the better before it's too late. It simply requires that we pray and act and expect God to change our human hearts. And that's certainly a matter for prayer and faith in response to our Harvest celebration.

At heart it's about how we love God and love our neighbour: do we love them enough to pray and act? In the words of the poem by G A Studdert Kennedy (the First World War chaplain 'Woodbine Willie') which we sang as a hymn this morning:

So let the love of Jesus come

And set thy soul ablaze,

To give and give, and give again,

What God has given thee;

To spend thy self nor count the cost;

To serve right gloriously

The God who gave all worlds that are,

And all that are to be.

  No virus found in this incoming message.  Checked by AVG - www.avg.com   Version: 8.5.409 / Virus Database: 270.14.3/2412 - Release Date: 10/03/09 18:34:00