* Francis portrays defending nature as core part of faith
* Says citizens must insist Paris climate accord honoured (Adds quote, background)
By Crispian Balmer
ROME, Sept 1 (Reuters) - Pope Francis called on Thursday for concerted action against environmental degradation and climate change, renewing a fierce attack on consumerism and financial greed which, he said, were threatening the planet.
A year after publishing the first papal document dedicated to the environment, the pope urged Christians to make the defence of nature a core part of their faith, adding it to the seven "works of mercy" they are meant to perform.
"God gave us a bountiful garden, but we have turned it into a polluted wasteland of debris, desolation and filth," Francis said in a document released to coincide with the World Day of Prayer for the Care of Creation.
Born in Argentina, Francis is the first pope from a developing nation and has placed environmental causes at the heart of his papacy, denouncing what he sees as a throwaway consumer culture and rampant, market-driven economies.
"Economics and politics, society and culture cannot be dominated by thinking only of the short term and immediate financial or electoral gains," Francis said, suggesting more ambitious action might be needed to curb climate change.
World leaders agreed in Paris last December to commit to limiting greenhouse-gas emissions in an effort to stabilise rising temperatures, while the World Meteorological Organization (WMO) said in July the earth was warming faster than expected and on track for its hottest year ever.
Francis welcomed the Paris accord, but urged voters everywhere to make sure their governments did not backtrack.
"It is up to citizens to insist that this happen, and indeed to advocate for even more ambitious goals," he said.
He asked the world's one billion Roman Catholic to embrace a green agenda, saying defence of the environment should be added to the works of mercy, which provide believers with guiding principles and duties that they are meant to follow.
These include taking care of the hungry and sick, and teaching the ignorant. Six were spelled out in the New Testament; the seventh -- burying the dead -- was added in the Middle Ages.
"May the works of mercy also include care for our common home," Francis said, adding that simple, daily gestures which broke with "the logic of violence, exploitation and selfishness" would make a difference.
Even recycling rubbish, switching off lights and using a car pool or public transport would help, he said. "We must not think that these efforts are too small to improve our world."
Bishop Brian Farrell, head of the Pontifical Council for Promoting Christian Unity, said the pope's words did not represent new Church rules, but thought his suggestions would be assimilated by congregations around the world.
"It is obviously a rare thing to add to the acts of mercy, but things change. This shows the movement of the church through time. We need new calls for responsibility," he told Reuters.
(Reporting by Crispian Balmer; Editing by Jon Boyle and John Stonestreet)
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