State of the Planet

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‘The Big Ratchet’

Environmental geographer Ruth DeFries, a pioneer in studying how humans have transformed earth’s surface, is author of the new book The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis. She argues that we have continually created new technologies that allow our numbers to grow. But each new invention creates a new problem—which we solve with yet another innovation that creates the next problem. Will we be able to sustain this so-far successful cycle past the great leap in technology and population of the last century? DeFries, who co-directs the Earth Institute’s undergraduate program in sustainable development, discussed this and other questions recently.

(All photos: Ruth DeFries)

Q. The idea that there’s a limit to how far we can manipulate nature before something goes wrong: Is that new?
This goes back to Plato and Socrates, and most likely long before. We often talk about [18th-century philosopher Thomas] Malthus, because of his prophecies of famine at the height of the Industrial Revolution. But predictions of catastrophe and collapse haven’t turned out the way they’re prophesized. It’s human nature to extrapolate into the future from what you see around you, without taking into account human ingenuity. The predictions seem logical, but history tells a different story.

A. Your book describes a historical cycle you call “ratchet, hatchet, pivot.” Can you explain?
A ratchet is a tool which creates motion in one direction, so once you have that motion, you can’t go backward. We keep ratcheting up the ways to manipulate nature to produce more food. This allows civilization to support more and more people. But then, from manipulating nature on such a grand scale, it’s inevitable that a new problem results, whether it’s disease, or famine or pollutionthe hatchet. The solution is the pivot. Then the cycle starts again.

An example or two?
The domestication of crops was probably the biggest ratchet in history. The hatchet: diets became starchier. People became shorter, life expectancy dropped, there was tooth decay, and smallpox and tuberculosis from crowding. The pivot has been long and slow. Whenever people could afford to raise livestock, they have increased the animal products in their diets. We have also devised antibiotics and vaccinations to counteract diseases caused by crowding. A more recent example is the introduction of the potato from the New World to Europe, in the 16th century. Because it’s nutritious and grows easily, it is one reason population could grow. In Ireland, people relied almost solely on it, and potatoes were planted closely together. The potatoes were genetic clones, so when a fungus hit in the 1840s, it caused the Irish potato famine, which killed so many people. Ireland then stopped relying so much on the potato. Potatoes are not planted so close together anymore, and there are new varieties. People migrated out. While it was a tragic event, the aftermath shows the resilience to overcome and move on.


The last century, the ratchets turned faster than eversynthetic fertilizers,  genetically modified crops,  mechanized everything, booming population. Is our age different from all others?
One way that I think it is different is that the hatchets falling now have more to do with abundance. In the past, they had to do with shortage—shortage of fertilizer, shortage of food. Now, we see too much of certain things. Obesity is spreading worldwide. Too much nitrogen is causing pollution. Too much greenhouse gases. Our problems have mainly to do with the abundance we have created. We haven’t learned yet how to manage and live with it.

But we see also depredationdestruction of ecosystems, seas emptied of fish, faster than ever.
Resources may be declining faster now, but the phenomenon is not qualitatively different. People have always taken as much as they can. All species do the same thing. We just do it better now, because we have better technology.

For the first time, half of us now live in cities. Are we still connected to nature?
In a couple of decades, more than 70 percent of us will live in cities. That is a qualitatively different relationship with nature. Most of are not growing our own food; someone else is. In the United States less than 3 percent of people are farmers. But to me, it’s science fiction to think that even if every single one of us lived in cities, that we would be disconnected from nature. Even if you go into a grocery store and pull your shrink-wrapped chicken or whatever off the shelf, we still rely on the planetary support machinery. So many parts of that machinery are out of our control. Then again, I try hard not to hang onto this romantic notion that once, people lived in harmony with nature. While we can do much better with maintaining the ecosystems that we have, it’s not realistic to think that we can go back to some, really, fictitious harmony with nature.

Does it personally bother you to see so much of the planet converted to our own uses?
It does, because we can do better. We can all live well, and there’s enough food in the world to feed everyone right now. Yet, a billion people still don’t get enough food. We just haven’t learned to use our abundance efficiently. If we did, then we wouldn’t need to be destroying more nature.


Do you think your book will anger environmentalists?
There’s a line of thinking that the earth has a finite carrying capacity, and once we hit that, we will have some enormous catastrophe. The story is more complex. We have overcome problems time and time again. We need people who we might call alarmists to move on to solutions. I think someone like [Silent Spring author] Rachel Carson did a huge service by calling attention to the problems created by pesticides. But then again, if there’s too much doomsday thinking, which I think there is today, then people turn off. On the other side, you have people who say we have infinite resources, that technology and free enterprise will fix anything. Yes, technology can solve problems, but solutions just don’t arise spontaneously. It wasn’t because people sat back and said, ‘Oh, well, we don’t have anything to worry about.’ There’s a lot of hard work. I’m trying to step away from either extreme.

So, is there hope?
I do think there’s hope. I hope so. I don’t know what will happen in the future. Nobody knows. The only guide that we have is what’s happened in the past.

What are you doing yourself to live more efficiently?
I try my best. I compost. I eat very little red meat, and I’m very conscious about wasting food; I’ve been labeled “the tofu mom” by my kids. I try not to drive too much. I put my efforts into working with my students—they’re already making the world a better place. But as far as what anyone else should doI don’t want to get preachy.

DeFries will speak at a book launch Tuesday, Sept. 23, 6-7 pm, at the Italian Academy, Columbia University, 117 Street/Amsterdam Ave. Click for info and registration.

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Randolph Femmer
9 years ago

A serious, serious problem with the above story (and the interview) is that they convey no sense of emergency, urgency, or finite population limits (recall, however, that even by 1992 and 1993 1700 of the world’s top scientists – including 99 recipients of the Nobel Prize, the officers of the U.S. National Academy of Sciences and the Royal Society of London, together with top scientists from the Union of Concerned Scientists and 58 world science academies – issued FORMAL population-environment warnings).

Rather than accepting the sense of complacency offered in this article, we suggest taking a look at Carrying Capacity and Limiting Factors in real-world Population systems (see, for example, the fourth “Biospheric Literacy 101” PowerPoint at!powerpoints/c24vq as one example).

In addition, data sets from classical real-world Climb-and-Collapse population outcomes offer powerful (and profoundly-disquieting) insights into 99%-plus population die-offs and/or even worse mass mortalities in populations surrounded by seemingly ’empty’ conditions that remain 99.998% unoccupied (to envision such classical “too-late” / “they waited-too-long” real-world conditions in more familiar terms, imagine a circle approximately twice the size of a baseball on an otherwise empty basketball court!). For three such classical examples, together with the supporting mathematics for each, we suggest a brief PDF abstract on the topic at