We are, I promise you, not doomed, no matter what Jonathan Franzen says. We could be, of course, if we decided we really wanted to. We have had the potential for total annihilation since 1945, and the capacity for localized mayhem for as long as societies have existed. Climate change offers the easy choice of a slow destruction through inaction like the proverbial frog in the slowly boiling pot. And there are times when the certainty of inevitability seems comforting. Fighting is exhausting; fighting when victory seems uncertain or unlikely even more so. It’s tempting to retreat to a special place—a cozy nook, a mountaintop, a summer garden—wait for the apocalypse to run its course, and hope it will be gentle.

Science offers something close to certainty on many fronts, but on doom, it is ambiguous. The definitive things we can say are rooted in basic physics and clear measurements. The molecular structure of carbon dioxide means it can absorb the heat radiated by the planet. Carbon dioxide is the inevitable byproduct of combustion. Combustion—setting fire to long-dead plants and animals, liberating the never-used energy stored in their fossilized corpses —is a convenient way to power an industrial society. Adding a heat-trapping gas to the atmosphere makes it hotter. We have done so. We are not slowing down. Humans have emitted more carbon dioxide during my lifetime than in all the years of civilization that came before.

We are as confident as science ever allows us to be in some of the dangers in a warmer world.  As the average temperature warms, the abnormal becomes the new normal, and the new abnormal becomes the unprecedented. Heat waves grow more frequent and severe. We know, too, that warmer air holds more water vapor, and heavy downpours increase. Hurricanes feed off warmer sea surface temperatures. We are less confident, but have reason to fear that droughts will become more severe and frequent, that fires will rage uncontrollably, and that the sea could swallow our coastal cities.

All of these things are magnified as the temperature increases, but if there is a sharp break, it will not come at a degree and a half or two degrees. Degrees are a human construct, a way of measuring and recording differences and changes. Nature does not think in Fahrenheit or Celsius. When we pass the 2° limit, as we certainly will without immediate action, we will receive no warning sign. Things will carry on much as before. A frog in the pot can ignore an alarm and carry on boiling. It is not in the nature of frogs to heed such warning signs.

There are, of course, feedback processes to consider. Things change on a warmer world, and these changes can in turn warm the world, which changes things, and on and on in a vicious spiral toward unimaginable danger. But these feedbacks are not suddenly switched on at an arbitrary time. They are currently in operation, humming menacingly in the background. Most of them are not nasty surprises but unwelcome, persistent visitors, working in tandem to create the changes we live through in the present. The Arctic has lost more than a million square miles of sea ice in my lifetime. The loss of this reflective cover exposes absorbent ground below, warming the planet even more. This is a feedback. It is not a surprise.

This is not to say that there are no unexpected pitfalls on a warmer planet, no sudden shocks that could push us rapidly, like confused science fictional explorers, onto a functionally different planet. There are nasty surprises ahead. There are known unknowns, and unknown unknowns, and a whole spectrum of terrifying variations on half-known processes at work in the present. The risk of something terrible increases with the concentration of greenhouse gas in the atmosphere.

But it is precisely the fact that we understand the potential driver of doom that changes it from a foregone conclusion to a choice, a terrible outcome in the universe of all possible futures. I run models through my brain; I check them with the calculations I do on a computer. This is not optimism, or even hope. Even in the best of all possible worlds, I cannot offer the certainty of safety. Doom is a possibility; it may that we have already awakened a sleeping monster that will in the end devour the world. It may be that the very fact of human nature, whatever that is, forecloses any possibility of concerted action.

But I am a scientist, which means I believe in miracles. I live on one. We are improbable life on a perfect planet. No other place in the Universe has nooks or perfect mountaintops or small and beautiful gardens. A flower in a garden is an exquisite thing, rooted in soil formed from old rocks broken by weather. It breathes in sunlight and carbon dioxide and conjures its food as if by magic. For the flower to exist, a confluence of extraordinary things must happen. It needs land and air and light and water, all in the right proportion, and all at the right time. Pick it, isolate it, and watch it wither. Flowers, like people, cannot grow alone.