While some are concerned that human-induced global warming will devastate the planet, a new book called Unstoppable Global Warming points to nature as being the primary source of today’s modest temperature increases. Comments the book’s co-author, Dennis Avery: “More than 70 percent of the world’s recent global warming occurred between 1850 and 1940, before much human-emitted CO2 could be responsible. What could have caused this pre-industrial warming? Science points to the sun. Our book notes the startling correlation between earth’s varying temperatures and the length of the sunspot cycles. Human CO2 emissions have probably added to the modern warming, but their impact has apparently been very modest.”

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