In his Christmas address Archbishop Sean Brady has said that cocaine and other social drugs have emerged as a "real threat to society".
Along with Ireland's unfortunate reputation for alcohol use, substance abuse with so-called social drugs was emerging a serious challenge.
He also said that it was shocking that at a time when the Irish economy was performing well that 50 homeless men in Dublin and Belfast could have died over the past 18 months.
On a positive note Archbishop Brady said 2007 saw peace in Northern Ireland take hold for the first time in many, many years and also the first direct talks between Israelis and Palestinians in seven years.
"So there are many reasons to be hopeful", Archbishop Brady said.
Speaking about the challenges posed by global warming, Archbishop Brady said people needed to "alter our behaviour to the environment as a matter of urgency".