It's a funny old world. Environmentalists have been dancing with glee since Pope Francis issued a statement calling on every man, woman and child to stand together to tackle climate change. The pope, after all, is the leader of 1.2billion Roman Catholics around the world and a man who can bend the ear of any president or prime minister at any time he wants.Getting him on board the green bandwagon is an undoubted coup for the ecolobby.His statement was made in the form of an encyclical: a papal letter to bishops usually aimed at settling a debate on a theological issue, to be published today.It represents the pope's views on the God-given responsibility of humans to act as custodians of the Earth.Not only does he warn of the "unprecedented destruction of the ecosystem" but, in a less than subtle reference to so-called climate-change deniers, he argues that "the attitudes that stand in the way of a solution, even among believers, range from negation of the problem, to indifference, to convenient resignation or blind faith in technical solutions".Which is weird, because belief and blind faith are precisely what the pope usually demands of his many followers when it comes to deciding pretty much every area of their life from the cradle to the grave.Now, I'm sure that Pope Francis is a perfectly decent and moral man who means well and wants nothing but the best for mankind and our planet but - and it's quite a big but - the Catholic Church lost its right to hand out morality lectures some time ago.Whether you are a card-carrying eco-alarmist who worries daily about your carbon footprint or a Jeremy Clarkson, what the pope has to say about humans tackling climate change is about as relevant as Kim Kardashian's views on Greece and the future of the eurozone.First, like pretty much all political leaders who put their tuppence worth in on this issue, the pope knows next to nothing about climate science, which makes his opinion worth as little as mine.Second, popes don't have a particularly strong track record when it comes to tackling matters of fact and science over the years.It did, after all, take until 1992 for the Roman Catholic Church to formally acknowledge that it was wrong to persecute Galileo for proving in the 17th century that the Earth moves around the Sun, not the Sun around the Earth.And, as recently as 2009, Pope Benedict XVI was busy telling Africans facing Aids that condoms would not protect them from HIV, despite all the clear medical evidence to the contrary.But it's not just matters of science on which popes have time and again been wrong. It's on matters of basic morality too.When it comes to all of the great moral debates of our time, the Catholic Church has been on the wrong side of every one.Whether it's opposition to contraception, abortion, the right to die, divorce, gay marriage or women priests, the Catholic Church has clung to viewpoints stuck in the Dark Ages and has been wrong on every issue.And on most, but admittedly not all, of those issues, the church is even out of touch with its own congregations.Last year an international survey of Catholics found that most disagree with their church's teachings on contraception, divorce and abortion - three of the Vatican's key "moral" stances.But popes really come a cropper when they tell others to get their houses in order when we all know that the church has been responsible for one of the most shocking and evil cover-ups ever on an industrial scale: child sex abuse by its priests.Of course, the church's abusive priests are not the only people to have harmed children over the years. But since they used their unique access and position of trust in the church to commit that abuse, and when found out bishops and archbishops chose to cover up those crimes, the Catholic Church has a unique moral culpability for what has happened to thousands of innocent children.Even today, the Vatican is still dragging its feet in the attempts to uncover how high the cover-up extends and has failed to open up its records to enable the guilty to be prosecuted.So, for all those reasons, forgive me if I don't think the pope is in a position to lecture anyone - let alone the entire world - on this issue or anything else.If we are going to rely on the Catholic Church to teach us about science or morality, then God help us all. ..