Planet Earth should in theory be capable of supporting life, including human life, for thousands of years to come - indeed, some estimates say millions. It all depends on the human race. Not long ago the greatest danger seemed to come from nuclear war between the superpowers. Now the major threat is environmental damage, particularly the heating up of the atmosphere owing  to the discharge into it of so-called greenhouse gases such as methane and carbon dioxide. The prospect is not of an overnight catastrophe wiping out the human race in one sweep, but of a planet which can currently sustain a human population of six billion - and growing - finding within a generation or two that, due to global warming, the sustainable population is only a fraction of that - and falling. The effect would be something like that of the Irish potato famine, but on a global scale and lasting for centuries. Clearly millions would die in acute hardship and misery, and the poorest and most vulnerable would be the first to go.

However, there are still those who deny the reality of global warming. At the extreme end of that spectrum are those who allege that the scientific evidence has been cooked. More common is the acceptance of global warming as a natural phenomenon, caused by changes in the radiation from the sun. Both positions deny that there is any obligation on humanity to change its ways in order to head off an environmental catastrophe. A particular - and revealing - dislike is of any intervention that would interrupt the functioning of market forces (or the profitability of the oil industry).

Is one free to deny global warming if one so chooses? Is it a moral matter? To say so is not necessarily to want to go as far as the Bishop of London, Dr Richard Chartres, who faces the prospect of travelling to an international conference in Romania by train - a 37-hour journey with four changes. He famously said not long ago that air travel was a sin because of the greenhouse gases emitted ...

Cardinal William Levada, the new head of the Congregation for the Doctrine of the Faith, has yet to gain a reputation as either a hard man or a soft man. But on the basis of one of the most wide-ranging interviews he has given since his appointment last year - he was formerly Archbishop of San Francisco - he is certainly entitled to credit as an open-minded one. If his words (reported on page 27) indicate a general ...

Almost the whole burden of preserving the Anglican Communion from schism now rests on the shoulders of the Episcopal Church in the United States. It has about seven months to decide whether to comply with a tough package of conditions drawn up by the Anglican primates in Tanzania this week. If they fail, the Archbishop of Canterbury, Dr Rowan Williams, will refuse to invite their bishops to the next Lambeth Conference ...

The report by the Von Hügel Institute into the needs of recent Catholic migrants in London throws down a challenge to which the Church must respond. As a result of the accession of Eastern European countries to the European Union and Britain's relatively open-door policy towards them, tens of thousands of mainly young migrants find themselves away from home with only one familiar institution to turn to - the ...

The key subtext to the recent row over the right of Catholic adoption agencies to discriminate against homosexuals was the widespread public perception that the Catholic Church is a homophobic institution - a position reinforced by gay lobby groups, which regard the Church's defeat over the adoption issue as a singular triumph over a powerful enemy.

This ought not to be the case. It would be wise of the ...