Our New Climate Reality

Climate change has become such a familiar term that we tend to read past it — it’s part of our mental furniture, like urban sprawl or gun violence. So, let’s remember exactly what we’ve been up to, because it should fill us with awe; it’s by far the biggest thing humans have ever done.

Those of us in the fossil fuel-consuming classes have, over the last 200 years, dug up immense quantities of coal and gas and oil, and burned them: in car motors, basement furnaces, power plants, steel mills. When we burn them, the carbon atoms combine with oxygen atoms in the air to produce carbon dioxide. The molecular structure of carbon dioxide traps heat that would otherwise have radiated back out to space. We have, in other words, changed the energy balance of our planet, the amount of the sun’s heat that is returned to space.

Those of us who burn lots of fossil fuel have changed the way the world operates, fundamentally.

The scale of this change is the problem. If we just burned a little bit of fossil fuel, it wouldn’t matter. But we’ve burned enough to raise the concentration of carbon dioxide in the atmosphere from 275 parts per million to 400 parts per million in the course of 200 years. We’re on our way, on the present trajectory, to 700 parts per million or more. Because none of us knows what a “part per million” feels like, let me put it in other terms. The extra heat that we trap near the planet because of the carbon dioxide we’ve spewed is equivalent to the heat from 400,000 Hiroshima-sized bombs every day, or four each second. As we will see, this extraordinary amount of heat is wreaking enormous changes, but for now, don’t worry about the effects; just marvel at the magnitude: the extra carbon released to date, if it could be amassed in one place, would form a solid graphite column 25 meters in diameter that would stretch from here to the moon.

There are perhaps four other episodes in Earth’s 4.5-billion-year history where carbon dioxide has poured into the atmosphere in greater volumes, but never at greater speeds—right now we push about 40 billion tons into the atmosphere annually. Even during the dramatic moments at the end of the Permian Age, when most life went extinct, the carbon dioxide content of the atmosphere grew at perhaps one-tenth the current pace. The results, already, have been extraordinary.

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Climate change has become such a familiar term that we tend to read past it — it’s part of our mental furniture, like urban sprawl or gun violence. So, let’s remember exactly what we’ve been up to, because it should fill us with awe; it’s by far the biggest thing humans have ever done.