Why the Pope’s letter on climate change matters

Quirin Schiermeier in Nature:

PopeA very solid scientific consensus indicates that we are presently witnessing a disturbing warming of the climatic system.… It is true that there are other factors (such as volcanic activity, variations in the earth’s orbit and axis, the solar cycle), yet a number of scientific studies indicate that most global warming in recent decades is due to the great concentration of greenhouse gases (carbon dioxide, methane, nitrogen oxides and others) released mainly as a result of human activity.

This statement mirrors faithfully the basic conclusion at which the Intergovernmental Panel on Climate Change (IPCC) has arrived time and again. Cardinals who were involved in drafting the encyclical consulted leading scientists about the physical causes of climate change, so it is not surprising that science surfaces in the letter. But the Pope’s recognition of human-induced global warming is an unflinching rebuke to climate-change doubters who might have hoped to find an ally in the Catholic Church. No wonder many scientists have greeted the encyclical with unusual enthusiasm. “It is unique in that it brings together faith and moral with the world of reason and ingenuity,” said climate scientist Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK) in Germany, at a Vatican press conference today in Rome. “I can testify that everything in the encyclical is in line with science.”

More here.