There are now only 39 days to go until the world’s nations convene in Paris for the United Nations Climate Summit. Six years ago, talks in Copenhagen ended in chaos. Is there any reason to suppose Paris will deliver anything more than well-padded expense accounts for delegates and hot air on the issues?

In his new book, Atmosphere of Hope: Searching For Solutions To The Climate Change Crisis, best-selling Australian author Tim Flannery counsels cautious optimism by showing how the millions of small actions taken by individuals are driving down oil consumption and points out how new “Third Way” carbon-capture technologies promise to reduce emissions and create massive economic opportunities.

Speaking from a café in Melbourne, he explains how the plastic housing on his cell phone is reducing climate change; why geo-engineering is a disastrous idea; and how he is inspired by the desire to leave a better world for his three children.

A major climate change summit is about to take place in Paris. Is there any reason to assume that this won’t be another missed opportunity?

We can already proclaim it a success at least as far as the unconditional pledges that have been made in the run up to the summit. They are now sufficient to get us off the worst-case scenario trajectory of the last decade, when emissions were at the worst extent imaginable.

At the moment, we’re heading for four degrees [in global] warming by the end of the century. Hopefully, the Paris meeting will see us heading more towards three degrees. That is still far too much, but far better than four. There have been 20 years of annual meetings with no decisions made on a global agreement. But it looks like we’ll get one in Paris, which could be the beginning of a new era in dealing with climate change.

View Images Photograph courtesy Atlantic Monthly Press

Your book opens with a sport I love. What do Rod Laver and tennis have to do with climate change?

The Australian Open in Melbourne is one of the great events on the tennis calendar. Last year, an unprecedented heat wave settled over Melbourne spiking temperatures three days running in the Rod Laver Arena above 40 degrees centigrade (104 F) We had 1,000 spectators and several players treated for heat stress. Eventually play had to be cancelled because conditions were so dangerous.

The news outlets were reluctant to cover it as a climate change story. I wrote a story for the BBC in London and they called me back to say, “Unless you can tell us definitively that climate change has caused this, we’re not interested in running the story.” But since then it has become clear that climate change was, indeed, a decisive factor.

Heat waves are symptoms of the climatic extremes being caused by global warming. In 2009, here in Melbourne, bushfires killed about 150 people. In the four days leading up to those fires, there were also about 500 excess deaths from extreme heat conditions.

We’re seeing it globally now. People who are economically poorly off, very young, old or in ill health are having difficulty coping with these extreme heat conditions, and are dying at a much faster rate than they would otherwise.

A recent study says that the bleaching of coral reefs is now “a major global event.” How does the Great Barrier Reef, in your own country, show evidence of this?

Sadly, about 50 percent of the Great Barrier Reef is already dead. There are a number of factors that have been influencing this but, increasingly, it’s acid and heat causing the damage. I’ve come to the realization that the Great Barrier Reef is now the walking dead. Enjoy it while we’ve got it, but we can’t be sure it’ll be there by the end of the century.

View Images Climate change is sparking ever more violent wildfires. This woman in Craigieburn, near Melbourne, Australia, in March 2014, had time to grab her bags and run. Photograph by Edu Saraiva, Demotix/Corbis

In the last decade, the threat of climate change has spawned new ideas and technology. Tell us about geo-engineering and why a plan to shoot sulphur into the stratosphere is bad news for the planet.

The world is thinking about solving the climate problem by reducing emissions. If we can’t do that fast enough through the Paris Agreement, a number of governments are now looking at a “second way” of dealing it— geo-engineering. That includes proposals to shoot sulphur into the stratosphere.

We know from the research that it’s fairly cheap and seems to be effective in cooling the Earth. But it does nothing to deal with the underlying causes. Carbon dioxide will continue to build up; oceans will continue to acidify and the potential for extreme heat events will get worse.

Putting sulphur into the stratosphere would also change the climate. The South Asian monsoon, for instance, would be affected by stratospheric sulphur. About 1.4 billion people depend upon the monsoon for their food and existence.

There’s no global treaty to coordinate activities in this area, so a country like China, which is very active in this field, may decide to use sulphur unilaterally. This would have massive impact on places like India, and could quickly lead to conflict. Geo-engineering is a Band-Aid solution using poison to fight poison, which will lead to disaster.

View Images Twilight for a natural wonder. Rising temperatures and acidification mean the Great Barrier Reef is now “the walking dead,” says author. Photograph by David Doubilet, National Geographic

There are millions of people in America and elsewhere who still deny that climate change is induced by human activity. Make your case, Tim.

We can demonstrate in a laboratory the warming potential of CO2; we can measure the levels of CO2 in the atmosphere and determine where CO2 and other greenhouse gases have come from, and measure their impact on Earth’s climate systems. What we see is very much in line with the basic physics of how CO2 works; and in line with the thesis that CO2 is being generated by humans.

We are putting 40 gigatons of CO2 into the atmosphere every year. To give you a sense of how much that is, if you wanted to remove just four gigatons of CO2 out of the atmosphere by planting trees, you’d need to cover an area the size of the United States with forests, then plant an area the size of New York State once a year for 50 years.

Unfortunately, for many people it is not about science: it’s about ideology. It’s about what political party or cultural group they identify with. Others are contrarians and won’t accept the evidence anyway. I’m told there are people who still believe the Earth is flat [laughs]

You write that the cost of burning coal to the American economy is “between $175 billion and $523 billion.” Explain how you arrive at those numbers.

Those numbers are now a few years old, when coal was being burned at a much greater level than it is now in the U.S. They come from Harvard Medical School’s breakdown of all of the costs from healthcare to climate impact. From health impacts alone, the figures this year show that around 30,000 Americans will die from coal burning. When you think of the health costs, family impacts and human costs of coal, it is very substantial indeed.

Fracking has revolutionized oil production and sent prices at the pump tumbling. That’s a good thing, surely?

Yes, it’s a good thing. But there are other environmental and health costs to fracking, like fugitive emissions and groundwater impacts. The price of oil tumbling also hasn’t solely been due to fracking. There are other factors at play. One of the most important is energy efficiency.

View Images Fracking, as at this shale gas well near Towanda, PA, has sent pump prices plummeting. The potential environmental costs will show up later. Photograph by Mark Thiessen, National Geographic

Actions that so many of us have been doing for so long, with so little hope in our hearts, like changing light bulbs, getting better insulation or cycling to work are having a very large impact on oil demand. For the first time in 40 years, according to the National Energy Agency, there’s been a decoupling of global economic growth with emissions growth from the burning of fossil fuels. That is unbelievably good news, due in part to those billions of small actions individuals have taken to become more efficient. And it’s happened many years in advance of what anyone thought possible.

Let’s stick with good news. You write, “The rate and scale at which our cities are being transformed is astounding.” Give us some examples.

The increasing densification of urban centres has allowed for enormous efficiencies. Things like bike paths or light rail are becoming features, so too is energy generation using waste and solar panels on rooftops. These transformations are bringing about massive efficiencies. It is the engine of decoupling from fossil fuels and is now a two-trillion-dollars-a-year industry worldwide.

Other scientific innovations that offer hope are “smart” chemistry and biology, which I call a “Third Way” to deal with climate change. Third way technologies are means of drawing CO2 out of the atmosphere at a faster rate than it occurs naturally and in ways that strengthen earth’s systems to self-regulate. Some of them, like reforestation, are very simple.

People are also making bio-chars, a mineralized form of carbon that uses mineralized plant matter. I have a small plastic mobile phone housing - probably the most expensive mobile housing in the known universe [Laughs] –made from atmospheric CO2! We’re at the edge of seeing this vast world change where the problem—the CO2 and methane in the atmosphere—becomes the solution.

What makes you so passionate about this subject, Tim?

I love my world! I love the diversity of nature. I cherish our global civilization, the great achievements of humanity, and I can see them all being put needlessly at risk by pollution from the fossil fuel industry, which we really don’t need anymore. We don’t need its products anymore, or its pollution. We have new ways of generating energy: efficient, clean, cost-effective ways. And the faster we move to that new world the less the threat to all of the things that I cherish about this world.

I have three kids who have every chance of being alive in the late 21st century. When I think about the world I might bequeath them, I am horrified. The three-degree world is not the sort of world anyone should want to live in.

We have to get down to well below two degrees. That’s why I wrote my book. We have to slam down on emissions; avoid the “second way” of geo-engineering and start R&D of scale on “ Third Way” technologies that, I am convinced, will represent a tech boom that will dwarf the tech boom wind and solar has given us.

Five years ago in the wake of the failure of Copenhagen I despaired that we could reduce emissions. Paris gives me hope that we can do that and also cull back some of the emissions that we have been pouring into the air in this decade of failure.