"THE environmental challenges facing humanity in the 21st century are immense: the most urgent and pressing is climate change" (Church and Earth 2009-2016, C of E, 2009).

The world has just passed the symbolic and ominous figure of 400 parts per million of carbon dioxide in the atmosphere. This is halfway between the 350ppm that is thought to be "safe", and the 450ppm that is widely regarded as a threshold for dangerous climate change. This should set alarm bells ringing even louder, and provoke action to prevent climate disruption wrecking the lives of the world's most disadvantaged communities.

To put this figure in context, for the past few hundreds of thousands of years, carbon-dioxide concentration has been going up and down between about 180 and 280 ppm. For the period of human civilisation, it has been remarkably stable, until the industrial revolution, and especially the past 50 years, when it has been rising. It is now 40 per cent higher than at any time in the past few million years, and going up.

This is an extremely rapid rate of change for the planet to adjust to. Changing the atmosphere at this rate inevitably causes instability in the climate, and many more severe weather events. Unless it is stabilised, this could do devastating damage to the world in which our grandchildren will live.

WE ARE halfway between 2009 and 2016. These were the start and end dates for the C of E's "seven-year plan on climate change and the environment". It was published in one of its most exciting, and yet probably least-well-known reports, Church and Earth (available at: www.churchcare.co.uk/shrinking-the-footprint).

Commissioned by the Bishop of London, the Rt Revd Richard Chartres, and overseen by a steering group drawn from inside and outside the Church, the report complements the C of E Shrinking the Footprint campaign, and provides a strategic vision for parishes, dioceses, and church partnerships. It provides practical recommendations, case studies of action that has already been taken, and charts a way ahead.

NOW that we are halfway through the seven-year period, and especially now that a fresh sense of urgency about climate action is imperative, it is worth the Church's taking stock about how things are going.

Church and Earth takes the urgency seriously, but does not dwell on doom and fear. On the contrary, it celebrates the projects that are under way in many dioceses, and documents progress - for example, the Devon Christian Climate Change Coalition in Exeter diocese, solar power in use in St James's, Piccadilly, in London, and an "eco-church" in Addington. The report makes a strong case for saying that "good ecology is not an optional extra, but a matter of justice. It is therefore central to what it means to be a Christian."

It lays out proposals for future action. It looks at buildings and assets, partnerships with civic groups and other faiths, work with schools and young people, lifestyles, pastoral and community projects, media and advocacy, celebration and worship.

Shrinking the Footprint continues its vital work of measuring the carbon footprint of the Church's total building stock, and looks to further work covering water and biodiversity, transport, waste, land, and food. Links are well established with various environment agencies and Christian groups, such as A Rocha and Operation Noah, as well as development agencies such as Christian Aid.

Ideas for a code for sustainable churches, tree-planting projects, new action on waste and recycling, the perils of fuel poverty, the greening of cathedrals and retreat houses are all being developed.

The Church will continue to monitor and influence the companies in which it invests. In the light of recent news about "unburnable fuel reserves", it has been suggested that the Church should work by 2020 towards disinvestment from fossil-fuel extraction and supply companies. The aim would be a portfolio that is carbon-neutral, while offering maximal return for minimal environmental and social impact.

A bishops' environment panel and a network of diocesan environment officers are now in place, and a climate-justice Fund has been established.

ALTHOUGH the environmental challenges facing humanity are immense, the scale of the challenge demands that people across civil society play a full part, not only in demanding action from government and business, but also in living out the values and lifestyle changes that will enable a sustainable world for all.

The report Church and Earth affirms that the Church and its partners and allies have a vital contribution to make here. "The service of Christians and others of faith and goodwill can contribute positively to the resources and energy of human beings around the world, to mitigate climate change, adapt to it, safeguard the poor and vulnerable, and conserve life's richness for the benefit of all."

The report ends with a note of hope, and trust in God's commitment to the creation and to humanity, and by saying: "The Church of England has pledged itself to playing its full part in this great work before us all."

At this halfway stage in the seven-year plan, it would be good for all of us to renew this pledge, at personal, parish, diocesan, and national church level. The Shrinking the Footprint campaign is encouraging parishes to conduct new audits of energy-saving measures.

The Church needs to take more of a lead in monitoring its plan. Diocesan synods and the General Synod could timetable stocktaking debates. This agenda is hugely more important than many of the subjects that occupy synodical time. The work that has been done so far offers a rich set of projects and statements of intent on which to build.

Dr David Atkinson is an Assistant Bishop in the diocese of Southwark.