His Holiness Pope Francis delivers his message during the General Audience of senior Government Officials and members of the Diplomatic Corps at the Rizal Hall of the Malacañan Palace for the State Visit and Apostolic Journey to the Republic of the Philippines. 16/01/15 Source: Malacañang Photo Bureau. Author: Benhur Arcayan

When talking about climate change, ethical arguments have tended to be overshadowed by scientific, economic and political reasoning.  Of course, there are many good reasons to go after a strong and unequivocal climate agreement in Paris. Since 1990, five IPCC (UN Intergovernmental Panel on Climate Change) assessment reports, using building scientific evidence, have warned us again and again about the catastrophic risks posed by greenhouse gas emissions.

The increasingly destructive effects of climate change are ramping up its urgency and raises questions about justice for all. As soon as it was understood that catastrophic climate change is already affecting millions of mainly poor people who are the most vulnerable while being the least responsible for dangerous global warming it became an ethical issue. As Greenpeace International Political Director Daniel Mittler, put it, "climate change is no longer merely an issue to prepare for. Its effects are happening now. They are already real – and all too often deadly – today". 

With many governments either stymieing or ignoring the issue and big industrial interests putting profit ahead of responsibility, catastrophic climate change will increasingly threaten the poor of the world. Climate change is here, today, and already affects millions of people with direct and indirect impacts; affecting water availability, endangering food production, and displacing people. Climate change can increase the risk of conflicts. Fossil fuels and wars for resources – energy, water, food – are interconnected.

Biodiversity Banner on Christ the Redeemer Statue. 03/16/2006 © Greenpeace / Daniel Beltrá

Putting the ethics back at the heart of the environmental argument, the Laudato si encyclical used the IPCC assessment as the basis for this theological discourse. Naturally, it would then come to the very same conclusions: climate change poses a fundamental moral and ethical issue of justice which calls for a radical change in policies, lifestyles and visions of the future. It's not just a strong message to the 1.2 billion Catholics in the world, it is, in a way, the sounding of Gabriel's horn for everyone, everywhere. 

Inter-faith and grassroots initiatives are growing. Take the Roman march, "One Earth, one human family" next Sunday, June 28th to St Peter's square, which will be addressed by the Pope. 

For Greenpeace, which has been campaigning on climate change for the past 25 years, this encyclical is good news. The ethical rallying cry we've all been raising about the climate has just been amplified to millions of fresh ears. This must increase the pressure on our leaders to act at the behest of the largest climate coalition ever seen, billions of citizens around the world.

Giuseppe Onufrio is the Executive Director of Greenpeace Italy.