Scientists are beginning to understand the circumstances of five mass extinctions that transformed the world over the past 4½ billion years.

For example, a giant asteroid collided with earth with the force of 100 million mega-tonnes of TNT 66 million years ago, plunging the planet into cold and darkness, wiping out three-quarters of all species (including the dinosaurs) and ending the Cretaceous period. That cataclysm was not explained until 1980, by Walter Alvarez, a geologist, and his father, Luis, a physicist.

We are now rushing headlong into a sixth mass extinction, but this time the culprit is man, Elizabeth Kolbert writes in her best-selling book, The Sixth Extinction; An Unnatural History, which won a Pulitzer Prize last April.

Kolbert travelled the world, from the Americas to the Great Barrier Reef to Europe, to document vanishing frogs, bats, rhinoceroses, coral. In our Anthropocene age, named for the impact of human activity, increasing numbers of species exist only in “frozen zoos”, their cells preserved in pools of liquid nitrogen at -195 degrees.

Towards oblivion

Amphibians, which have been around for 250 million years, are now the most endangered species. “But extinction rates among many other groups are approaching amphibian levels,” Kolbert writes.

“It is estimated that one-third of all reef-building corals, a third of all fresh water mollusks, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles and a sixth of all birds are headed towards oblivion.”

The early 19th-century French naturalist Georges Cuvier discovered that earlier species had become extinct, paving the way for Charles Darwin’s theory of evolution.

The sixth extinction is characterised by its rapidity, Kolbert explained in a telephone interview from her home in Massachusetts.

“Most of the great mass extinctions of the past unfolded over thousands of years. The rates at present are phenomenally high,” Kolbert said. “If we keep this up for another 500 years – long for humans but very short for the planet – the general consensus is that we are in a very serious extinction event.”

Kolbert’s book explains the “dark synergy” between climate change, the acidification of the oceans and “fragmentation” – the fact that “Tundra is crisscrossed by pipelines . . . Ranches and plantations and hydroelectric projects slice through the rainforest”. The funguses that are killing off frogs and bats in their millions were propagated by air travel.

“So far,” Kolbert said, “there is not a clearly documented case of a species driven to extinction by climate change.” But global warming is pushing temperatures to extremes not seen for hundreds of millions of years. Life forms may not be able to adapt. “All the scientific literature predicts that climate change will become a major driver of extinction over this century.”

Humans are already fleeing the results of climate change, especially in Africa. “The refugee crisis in Europe should be a wake-up call,” Kolbert said. “It’s a vision of what’s to come in a world where life is going to get harder and harder.”

The UN’s COP21 conference will convene in Paris from November 30th-December 11th with a mission to slow climate change.

“The word on the street is that it’s very likely some sort of agreement will come out of Paris,” Kolbert said. “It will be hailed – perhaps rightly – as a watershed moment. But the defining question is: when do we see global emissions actually start to drop? Is Paris a success if emissions continue to rise for 10, 20 or 30 years?”

A 20-page draft treaty published on October 5th sets no date for reducing greenhouse gas emissions. Though the threat of global warming has been understood since the late 1980s, carbon dioxide emissions have continued to rise, from six billion metric tonnes annually in the early 1990s to nearly 10 billion metric tonnes at present.

Arbitrary target

The treaty will set the target of limiting the rise in global temperature to 1.5 or 2 degrees Celsius by the end of this century. Scientists say there will be substantial risks to the environment beyond a 1.5 degree rise, but there is a consensus that even 2 degrees is unrealistic.

“We are already seeing the impact. We’re already seeing Antarctica start to go, and we aren’t even at 2 degrees yet,” Kolbert said. “Two degrees was always an arbitrary point. We are probably going to go over 2 degrees, but we can’t give up because that would mean an even greater level of disaster.”

Kolbert believes “there is way too much emphasis on the words in the treaty”, which is ultimately only a piece of paper.

“What matters are the emissions. There is almost nothing that is or is not in the treaty that is going to make or break this. Are countries going to realise that it’s in their interest to reduce emissions? If so, there is hope. If not, the treaty is not going to make it happen.”

That world leaders will gather in Paris to sign a treaty against climate change while they continue to subsidise massively the production and consumption of hydrocarbons seems the height of hypocrisy. The Organisation for Economic Co-operation and Development estimates subsidies at US$500 billion annually, though other calculations run much higher.

By contrast, developed countries have mustered only US$57 billion for each of the past two years for the “Green Climate Fund,” to which they pledged US$100 billion annually to help developing countries tackle climate change.

The carbon subsidies are “completely wrong”, Kolbert said. “On every level, it’s crazy and self-defeating, but we keep doing it.”

She likened the problem to the “prisoner’s dilemma”, a game theory in which rational individuals refuse to co-operate, although to do so would be in their interest. “Everyone has to make the renunciation [of hydrocarbon subsidies] at the same time. Otherwise people are gaming the system, and no one wants to be the one making the sacrifice.”

Almost no one in Europe now doubts the reality of climate change.

“Europeans are coming to it from the perspective of a continent that saw terrible things in the past century. They’ve come to believe in the need for global co-operation.

“I don’t think that consciousness has come to every part of the world yet. In the US, we still have presidential candidates who are doing extremely well in the polls who deny global warming exists. It is quite likely that one of them will be the Republican nominee . . . It’s become one of the things you almost have to say to get the Republican nomination.”

Use of fear

Though she believes climate change is “the great cause of our time”, Kolbert is sceptical about the reliability of the INDCs (Intended Nationally Determined Contributions) upon which the Paris treaty will be based. She regards predictions that the world will “come together” in a great shift of moral consciousness as naive.

“Fear is a very good motivator,” Kolbert said. “And if people are afraid that their kids are not going to have a future, they can be motivated.” Action taken in the 1980s to stop the spread of the “ozone hole” which exposed the earth to ultraviolet radiation is a good example. “The world is capable of changing if it wants to.”