Go Forth and Multiply but Then Subtract, Priest Warns Couples. Fr Sean McDonagh, a Columban missionary and expert on the environment, says that unless we reduce population growth, more than 11,000 species face extinction. In his latest book, 'The Death of Life' he says that the size of the world's population is such that the Catholic Church must revisit its teaching on birth control. The teaching that each act of sexual intercourse must be open to life leads to larger families, that will stress global ecosystems within four or five decades. This lead to a dramatic fall in human population which may well be permanent because the damage to the earth's fertility could be irreversible. Fr McDonagh claims that the battle to save the planet is as important as the fight against slavery or to secure workers' rights. He says that political and economic decision-makers do not appreciate the way that insatiable demands are tearing apart the web of life, with disastrous consequences for future generations and also accuses the Church of staying silent about the threat to the environment throughout most of the 20th century. January 18, 2005 Irish Independent