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Nature Watch: We must take seriously the threat of global warming

Consider two documents. Pope Francis’ encyclical, “On Care of Our Common Home,” and “Mass Extinction: It’s the End of the World as We Know It,” an interview of University of Arizona evolutionary biology professor Guy McPherson.

Francis has gained world recognition that is derived from his public humility, his concern for the poor, his progressive policies and his straightforward responses to unacceptable behavior by individual clergy.

If it were not for that recognition, I believe that his encyclical about the threat to the Earth of climate change would be filed away and forgotten as have past papal statements. (Can you identify one?) Unlike them, this statement will, I hope, gain more traction because the pope speaks to the moral side of today’s most serious problem, a problem that has been identified by scientists for years but has either not bothered or been rejected by half of our population. (A 2014 Yale poll showed only 45 percent of registered voters “more likely to vote for a candidate who strongly supports taking action to reduce global warming.”)

At a Sierra Club writers’ group meeting recently, Sister Eileen O’Connor reviewed the chapters of this 245-paragraph encyclical. Here are only a few high points I took from the original document and from sister’s summary:

Although the encyclical has been identified as about climate change, Francis places that problem within a more general concern about our culture, devoting much of the document to topics like pollution and our throw-away society. Specifically he discusses the interconnection of all aspects of nature: water shortages, the disproportionate effect climate change has on the poor, our rapid loss of biodiversity, the decline in our quality of life despite our powerful technology and our weak responses to these serious problems.

The encyclical devotes an entire chapter to our responsibility for global warming, accepting the scientific view that we are causing climate change but placing that acceptance in a moral framework. To address these problems, Francis calls for a cultural shift involving not just governmental activities but also changes in personal lifestyle and thinking about a world we are abusing in significant ways.

This is clearly a religious document and about a third speaks directly to the pope’s Catholic community –about 1.2 billion people, one-sixth of the world population. But the message of the rest of the document is a broader appeal to all humanity, calling for a moral conversion, not a Catholic conversion.

For several decades, I have been reading dire scientific forecasts that warn us to do something before it is too late. McPherson and the papers the article about him reference tell us that we are already too late: we have passed the point at which we could have headed off catastrophe. We are well into the sixth great extinction and that extinction includes us.

McPherson frames his argument in terms of feedback loops. A feedback loop is a self-reinforcing activity. For example, a vast amount of methane, “a greenhouse gas 100 times more potent than carbon dioxide,” is captured in the Arctic permafrost. Rising temperatures are melting that ice and releasing the gas, which contributes to further warming.

The cycle is then repeated. Dozens of similar feedback loops are already working against us, he points out, and it is too late to stop them.

The threat of global warming is, I suggest, every bit as threatening as a comet heading for Earth. And if McPherson is right, we are, to use a different but appropriate analogy, toast.

At the very least, we should take Francis’ message to heart and take climate change seriously. Both documents are accessible on the Web. I recommend that you study them.