Pope Francis' encyclical released Thursday calls for action on climate change, which he says "represents one of the principal challenges facing humanity in our day."
In the document, the draft of which was leaked earlier this week, Francis says climate change is mainly the result of human activity. He urges that fossil fuels be "progressively replaced without delay," adding that, "If present trends continue, this century may well witness extraordinary climate change and an unprecedented destruction of ecosystems, with serious consequences for all of us."
"The earth, our home, is beginning to look more and more like an immense pile of filth," Francis adds. "In many parts of the planet, the elderly lament that once beautiful landscapes are now covered with rubbish. ... Frequently no measures are taken until after people's health has been irreversibly affected."
Francis says poor nations will be negatively impacted the most by climate change, and that developing countries need to do more to curb Earth-warming pollution.
"The 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 programs of sustainable development," he wrote.