Pope Benedict XVI waves to the crowd from inside his popemobile as he arrives to visit the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Daniel Roland/Pool (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Arnd Wiegmann (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Arnd Wiegmann (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. Pictured at left is archbishop Robert Zollitsch. REUTERS/Arnd Wiegmann (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI waves to the crowd from inside his popemobile as he arrives to visit the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Daniel Roland/Pool (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI waves to the crowd from inside his popemobile as he arrives to visit the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Daniel Roland/Pool (GERMANY - Tags: POLITICS RELIGION)

People gather outside the Freiburg Cathedral as Pope Benedict XVI pays a visit there, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Arnd Wiegmann (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI waves to the crowd from inside his popemobile as he leaves after visiting the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI waves to the crowd from inside his popemobile as he leaves after visiting the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI gestures as he addresses the audience during his visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI gestures as he addresses the audience during his visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI gestures as he addresses the audience during his visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI, accompanied by archbishop Robert Zollitsch (R) stands in front of a relief showing himself during his visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI, accompanied by Vatican Secretary of State Cardinal Tarcisio Bertone (L) and archbishop Robert Zollitsch (R) stands in front of a relief showing himself during his visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

State premier of Baden-Wuerttemberg Winfried Kretschmann presents a gift to Pope Benedict XVI at Freiburger Muenster (Freiburg Minster) in the south-western German town of Freiburg September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism. REUTERS/Miro Kuzmanovic (GERMANY - Tags: POLITICS RELIGION) 

Pope Benedict XVI presents a goblet to archishop Robert Zollitsch (L) during a visit to the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism. The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI addresses the audience as he visits the Freiburg Cathedral, September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: POLITICS RELIGION)

Pope Benedict XVI visits the Cathedral in Freiburg September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: RELIGION POLITICS)

Pope Benedict XVI visits the Cathedral in Freiburg September 24, 2011. Pope Benedict has praised Catholics in eastern Germany who held on to their Christian beliefs despite the "acid rain" that corroded their faith under the Nazis and communism.The Bavarian-born pontiff is on a four-day visit to Germany, his third visit to his homeland since he took over as head of the Catholic church. REUTERS/Max Rossi (GERMANY - Tags: RELIGION POLITICS)

A fisherman rows a boat in the algae-filled Chaohu Lake in Hefei, Anhui province July 3, 2011. More than half of China's cities are affected by acid rain and one-sixth of major rivers are so polluted the water is unfit even for farmland, a senior official said in a bleak assessment of the environmental price of the country's economic boom. Picture taken July 3, 2011. REUTERS/Stringer (CHINA - Tags: ENVIRONMENT) 

A fisherman rows a boat in the algae-filled Chaohu Lake in Hefei, Anhui province July 3, 2011. More than half of China's cities are affected by acid rain and one-sixth of major rivers are so polluted the water is unfit even for farmland, a senior official said in a bleak assessment of the environmental price of the country's economic boom. Picture taken July 3, 2011. REUTERS/Stringer (CHINA - Tags: ENVIRONMENT) 

CLIMATE/ACIDIFICATION - 3D illustration explaining how ocean acidification occurs. RNGS. (SIN05) 

A security personnel sits in front of an environment-related billboard on Changan Avenue in Beijing June 5, 2009. China cut its water pollution and emissions of acid rain-causing sulphur dioxide last year, as it stepped up efforts to make its economic growth cleaner, state media said. REUTERS/Grace Liang (CHINA ENVIRONMENT SOCIETY) 

Smoke billows from chimneys at chemical factories on the outskirts of Nanjing, Jiangsu province December 23, 2008. China cut its emissions of water pollution and acid rain-causing sulphur dioxide in the first half of this year, as Beijing closed dirty power plants and the global economic crisis hit heavy industry, state media said. REUTERS/Jeff Xu (CHINA) 

People walk next to a factory located next to a coal-burning power station in Beijing November 20, 2008. China cut its emissions of water pollution and acid rain-causing sulphur dioxide in the first half of this year, as Beijing closed dirty power plants and the global economic crisis hit heavy industry, state media said. REUTERS/David Gray (CHINA) 

A man walks towards a factory located next to a coal-burning power station in Beijing November 20, 2008. China cut its emissions of water pollution and acid rain-causing sulphur dioxide in the first half of this year, as Beijing closed dirty power plants and the global economic crisis hit heavy industry, state media said. REUTERS/David Gray (CHINA) 

A woman wears a face mask as she rides her bicycle past bare trees in central Beijing January 2, 2008. China has introduced cleaner fuel standards in its capital Beijing, its latest effort to curb the city's notorious pollution ahead of the Olympic Games in August. Under the new standards, authorities are hoping to cut emissions of acid rain-causing sulphur dioxide by 1,840 tonnes, official media reported citing Beijing's Environmental Protection Bureau. REUTERS/David Gray (CHINA) 

Cars, trucks and buses cause traffic congestion on a main road in Beijing January 2, 2008. China has introduced cleaner fuel standards in its capital, its latest effort to curb the city's notorious pollution ahead of the Olympic Games in August. Under the new standards, authorities are hoping to cut emissions of acid rain-causing sulphur dioxide by 1,840 tonnes, official media reported citing Beijing's Environmental Protection Bureau. REUTERS/David Gray (CHINA) 

A man rides his bicycle across a pedestrian bridge as cars travel on the road below in Beijing January 2, 2008. China has introduced cleaner fuel standards in its capital, its latest effort to curb the city's notorious pollution ahead of the Olympic Games in August. Under the new standards, authorities are hoping to cut emissions of acid rain-causing sulphar dioxide by 1,840 tonnes, official media reported citing Beijing's Environmental Protection Bureau. REUTERS/David Gray (CHINA) 

A view of a cooling tower and the smoke stacks of a power plant in Beijing November 15, 2007. Two key measures of pollution in China have fallen slightly in what the country's environmental regulator claimed was a victory for its clean-up procedures, state media reported on Thursday. Emissions of sulphur dioxide, which belches from smokestacks and causes acid rain, fell by 1.81 percent in the first nine months of 2007 compared with the same period last year, the China Daily reported. REUTERS/Claro Cortes IV (CHINA) 

A view of a cooling tower and the smoke stacks of a power plant in Beijing November 15, 2007. Two key measures of pollution in China have fallen slightly in what the country's environmental regulator claimed was a victory for its clean-up procedures, state media reported on Thursday. Emissions of sulphur dioxide, which belches from smokestacks and causes acid rain, fell by 1.81 percent in the first nine months of 2007 compared with the same period last year, the China Daily reported. REUTERS/Claro Cortes IV (CHINA) 

A woman pedals her tricycle past a cooling tower and the smoke stacks of a power plant in Beijing November 15, 2007. Two key measures of pollution in China have fallen slightly in what the country's environmental regulator claimed was a victory for its clean-up procedures, state media reported on Thursday. Emissions of sulphur dioxide, which belches from smokestacks and causes acid rain, fell by 1.81 percent in the first nine months of 2007 compared with the same period last year, the China Daily reported. REUTERS/Claro Cortes IV (CHINA) 

An orthodox priest walks past a part of the west frieze of the Parthenon in the Acropolis museum in Athens, July 27, 2004. Parts of the west frieze of the Parthenon, built in 442 BC, were taken down and given a new home in the Acropolis museum. [The undertaking was one of the most important for archaeologists who over the years have transferred parts of the ancient monument to the museum to preserve them from the damage by acid rain that had eroded many. Two parts of the frieze were dismantled by Lord Elgin and are now housed in the British Museum.] 

A general view of the temple of the Parthenon in Athens July 27, 2004. The temple opened to the public for a special visit due to the official transfer ceremony of the part of the west frieze from the Parthenon to the Acropolis Museum. Parts of the west frieze of the Parthenon, built in 442 BC, were taken down and given a new home in the Acropolis museum. [The undertaking was one of the most important for archaeologists who over the years have transferred parts of the ancient monument to the museum to preserve them from the damage by acid rain that had eroded many. Two parts of the frieze were dismantled by Lord Elgin and are now housed in the British Museum.] 

A general view of the temple of the Parthenon in Athens July 27, 2004. The temple opened to the public for a special visit due to the official transfer ceremony of the part of the west frieze from the Parthenon to the Acropolis Museum. Parts of the west frieze of the Parthenon, built in 442 BC, were taken down and given a new home in the Acropolis museum. The undertaking was one of the most important for archaeologists who over the years have transferred parts of the ancient monument to the museum to preserve them from the damage by acid rain that had eroded many. Two parts of the frieze were dismantled by Lord Elgin and are now housed in the British Museum. REUTERS/John Kolesidis. JK/DL 

An orthodox priest walks past a part of the west frieze of the Parthenon in the Acropolis museum in Athens. An orthodox priest walks past a part of the west frieze of the Parthenon in the Acropolis museum in Athens, July 27, 2004. Parts of the west frieze of the Parthenon, built in 442 BC, were taken down and given a new home in the Acropolis museum. The undertaking was one of the most important for archaeologists who over the years have transferred parts of the ancient monument to the museum to preserve them from the damage by acid rain that had eroded many. Two parts of the frieze were dismantled by Lord Elgin and are now housed in the British Museum. REUTERS/John Kolesidis. 

A couple looks at the temple of Parthenon in Athens, July 27, 2004. The temple opened to the public for a special visit due to the official transfer ceremony of the part of the west frieze from the Parthenon to the Acropolis Museum. Parts of the west frieze of the Parthenon, built in 442 BC, were taken down and given a new home in the Acropolis museum. The undertaking was one of the most important for archaeologists who over the years have transferred parts of the ancient monument to the museum to preserve them from the damage by acid rain that had eroded many. Two parts of the frieze were dismantled by Lord Elgin and are now housed in the British Museum. REUTERS/John Kolesidis. JK 

A Chinese sanitary engineer surveys the Balizhang rubbish tip on the outskirts of Beijing December 5. With a population of 1.2 billion, and several hundred thousand aging state factories, China faces an environmental nightmare of material waste, acid-rain and polluted air and water.

CHINA 

A Chinese man walks through a junkyard located in Beijing's northeastern suburbs September 21. The World Bank estimates rampant pollution causes about 178,000 premature deaths in China's major cities every year, while acid rain takes a heavy toll on agriculture and forestry in the nation's south.

CHINA ENVIRONEMNT 

Patrick Arbor (R), Chairman of the Chicago Board of Trade, gives a tour of the trading floor to Evan O' Connell, a sixth-grade student from Glens Falls Middle School in Glens Falls, New York, March 26. O'Connell was at the CBOT to hear the results of the fourth annual pollution permit auction held March 25 at the CBOT. O'Connell helped raise $20,000 to purchase and retire 292 sulfur dioxide allowances to combat acid rain. One allowance equals one ton.

POLLUTION