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Scientists and activists warning of catastrophic man-made global warming should look at Earth’s long climate history, according to a co-founder of the environmental group Greenpeace. As it turns out, Earth is currently experiencing one of the coldest climates in its history.

“A well-documented record of global temperature over the past 65 million years shows that we have been in a major cooling period since the Eocene Thermal Maximum 50 million years ago,” Dr. Patrick Moore said at a lecture Wednesday hosted by the U.K.-based Global Warming Policy Foundation.

“The Earth was an average 16C warmer then, with most of the increased warmth at the higher latitudes,” said Moore, who helped found Greenpeace in the 1970s. “The entire planet, including the Arctic and Antarctica were ice-free and the land there was covered in forest.”

Moore, an ecologist, left Greenpeace in the 1980s because he thought the group had become too radical in its demands. Greenpeace disowned Moore, who is renowned by conservatives for skepticism over claims that humankind is causing catastrophic global warming.

Moore argues that manmade carbon dioxide emissions have been good for the planet, providing plants with nutrients they need to grow. In fact, scientists have observed a “greening” of the planet over the last couple decades because of higher CO2 levels.

More importantly, Moore argues the Earth was much warmer in its past and life thrived. Today’s climate by comparison is much colder, he argues.

“Glaciers began to form in Antarctica 30 million years ago and in the northern hemisphere 3 million years ago,” Moore said in his lecture. “Today, even in this interglacial period of the Pleistocene Ice Age, we are experiencing one of the coldest climates in the Earth’s history.

“The ancestors of every species on Earth today survived through what may have been the warmest time in the history of life,” Moore said. “It makes one wonder about dire predictions that even a 2C rise in temperature from pre-industrial times would cause mass extinctions and the destruction of civilization.”

While scientists today warn about rising global temperatures since the 1970s, a look at Earth’s climate history reveals a roughly 50 million year cooling trend — based on proxy data derived from oxygen isotope ratios from fossil foraminifera.