Rich nations have a moral obligation to replace fossil fuels with renewables, fight climate change and aid poorer countries to develop sustainably, Pope Francis said Thursday in his first major teaching letter on the environment.
The 192-page letter, 'Laudato Si (Be Praised) - On the Care of Our Common Home) aims to inspire Catholics and non-Catholics alike to protect the Earth, making changes to lifestyles and energy use.
Climate change is not just a "global problem with serious implications" but has an impact that is felt disproportionately by the world's poorest people, the encyclical argues.
"In different ways, developing countries, where the most important reserves of the biosphere are found, continue to fuel the development of richer countries at the cost of their own present and future," it states.
"Developed countries ought to help pay this debt by significantly limiting their consumption of non-renewable energy and by assisting poorer countries to support policies and programmes of sustainable development."
Developing countries were expected to welcome the encylical's message that rich countries has a "grave social debt" to the poor. And his message will strengthen their position at key talks in Paris later this year on a deal to tackle global warming, according to the UN's climate change chief Christiana Figueres.
The letter, which has been widely welcomed by environmental groups, includes a section on the latest scientific findings to describe what Francis calls "an ecological crisis".
Despite the church's long history of clashes with science, many academics have welcomed the pontiff's input. Presenting the encyclical to journalists on Thursday, cardinal Peter Turkson, who wrote a draft, said dialogue was "essential" to develop practical proposals.
A key issue, however, is how the encyclical will be received by sceptical conservatives in the United States, where leading Republicans have warned the UN they will undo president Barack Obama's climate polices.
The document was frostily received by Jeb Bush and another Roman Catholic US presidential candidate after Italian weekly L'Espresso published a leaked draft on its website earlier this week.
