Benedict XVI has been dubbed "the green Pope"
for his increasingly vocal concern about damage to the environment and
his plans to make the Vatican a carbon-neutral state.
The German-born pontiff has condemned rampant consumerism and bemoaned the
abuse of the planet's resources in speeches, encyclicals and during overseas
trips.
He has warned that humanity risks destroying the planet's ecosystems unless it listens to "the voice of the earth".
During his six-year-long papacy, the Vatican has installed photovoltaic cells on its main auditorium to convert sunlight into electricity.
He has criticised the "economic and political resistance" to fighting environmental degradation and denounced world leaders' failure to come up with a new climate change treaty at a UN conference in Copenhagen in Dec 2009.
He said the planet was being threatened by the same "self-centred and materialistic" way of thinking that sparked the global financial crisis.
Benedict has raised the alarm for African countries, where competition for water and mineral resources has led to wars, and for low-lying island states in the Pacific and Indian Ocean.
He has compared the current degradation of the planet by capitalist economies
to the environmental damage caused by Communist regimes in Eastern Europe
and the former Soviet Union.
Without respect for "God's laws of nature", there will be no peace
on Earth, the Pope has warned.
In his own backyard, Benedict oversaw the installation of 2,400 photovoltaic
panels on the huge roof of the Vatican's Nervi Hall, a venue for papal
audiences and music concerts that can hold 10,000 people.
The idea is that renewable energy should provide the 180-acre city state with
20 per cent of its electricity needs by 2020.
It is hoped that they will produce 300 kilowatt hours (MWh) of clean energy a
year and save the equivalent of 80 tonnes of oil each year.
The panels are invisible to visitors to the Vatican and leave its historic
skyline unchanged.
Until the project was initiated, the Vatican bought all its energy from Italy.