Back Forty: Global satellite data show where agriculture is wiping out wildlands

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By Gabriel Popkin

Back Forty: Global satellite data show where agriculture is wiping out wildlands

Restored prairie and corn rows share space on a farm in southwest Minnesota. Photo by Gabriel Popkin.

Anyone who’s paying attention knows by now that we’re losing natural ecosystems like forests and grasslands at an alarming rate. But we often hear less about what’s taking the place of those wild habitats. Recent research has shed some light on that question, revealing that much of the substitution over the past two decades came from corn, soybeans and other agricultural crops.

I caught wind of the story thanks to a social media post by the University of Maryland’s Global Land Analysis and Discovery group. I first learned about the GLAD lab when I wrote about satellite-based deforestation alerts they were piloting in 2016 — a capability that has now become routine. 

While you may not have heard of the lab, you may have seen its data in the form of Global Forest Watch or the World Resources Institute’s deforestation estimates, which make headlines annually. The lab has pioneered algorithms that crunch huge quantities of satellite data to tell stories about how the world’s land surface is changing, and it puts out a steady stream of interesting papers. 

When I heard about the lab’s latest study on the global boom in cropland area, I thought it offered an interesting new way to look at land-use change on a global scale. I was also primed to pay attention to cropland expansion because I had written a story a few months earlier, for FERN, about crops displacing native grasslands in the United States. I pitched a report on the new paper to Science and the resulting news story was published in December.

The top-line result of that study — that new crop fields have taken over an area the size of Texas and California combined since the start of the 21st century — is alarming, given how much the human footprint was already putting the squeeze on nature. Basically, the world is rapidly becoming one giant farm.

It’s interesting that these new crop fields are not located in the same places where trees are being cut down. For example, relatively few crop fields are directly replacing Amazon rainforest, the place probably most associated with deforestation in the public mind. Rather, in South America, new soybean fields often go into cattle pastures that were carved out of the forest in the past.

But new crop fields are encroaching on the Gran Chaco and the Cerrado, two massive, biodiversity-rich ecosystems in Brazil that are drier than the Amazon and get far less public attention. These soybeans are not grown to feed South Americans directly, but rather are turned into feed for animals in Europe and Asia.

Cropland can also shrink. In recent years, the greatest cropland contraction has occurred in the former Soviet Union, where farmers cultivated poor, marginal land under a centralized system. In a market-based system, it doesn’t make sense to farm these lands, and indeed many former fields are now returning to forest.  

At the continental scale, the fastest cropland expansion is happening in Africa, eating into both the rainforests of central Africa and the dry forests and savannas that cover much of the rest of sub-Saharan Africa. But it’s a different flavor of expansion. Rather than growing commodities for the global market, these farms are largely producing food for Africans. 

The cropland boom in Africa is one of the biggest emerging environmental stories on Earth. Africa is by far the fastest-growing continent. Its population is projected to roughly double by 2050. All those people will need to eat, and as they get richer, they will likely want the meat-rich diets that much of the rest of the world has gotten used to.

Meanwhile, sub-Saharan Africa lacks many of our modern agricultural technologies and has the world’s lowest crop yields. It takes an African farmer roughly three times as much land as the global average to produce a bushel of corn, for example, and five times as much land as a U.S. farmer.

That means more land must be cultivated, putting enormous pressure on forests and other natural ecosystems. On top of that, climate change is forecast to reduce yields and hurt African farmers more than those on any other continent.

Whether African agriculture can keep up with population growth and climate change is one of the biggest environmental and humanitarian stories of our time, with implications for the entire world. It will determine, obviously, how Africans eat, but also whether they can conserve the continent’s remaining biodiversity and one of the world’s last major intact forests — the rainforest of the Congo Basin. The forest also protects the world’s largest tropical peatland, estimated to contain as much carbon as the U.S. emits in 20 years.

The solution is almost certainly not to simply replace the current smallholder system, in which hundreds of millions of people farm small acreages, with American-style industrial agriculture, which comes with massive human displacement and sustainability concerns. And of course Africa is not a monolithic place but a vast, diverse patchwork of countries and cultures, each with its own agricultural traditions and challenges, making a one-size-fits-all solution impossible.

Rather, the question as I see it is, can Africa fuse the best of both systems into a new kind of technologically enhanced yet human-centered, sustainable and climate-resilient agriculture? Better yet, can African-led agricultural innovations, along with productive international partnerships, play key roles in increasing crop yields while relieving some of the pressure being placed on the continent’s remaining natural ecosystems?

This National Geographic feature from a few years captured some of the tensions facing African agriculture. But on the whole, the topic has received little coverage, at least in U.S. media, given its enormous importance both on the continent and around the world.

One thing is certain: the story of croplands displacing wildlands is far from over. But ever-more-powerful satellite data coming online will at least help us understand the problem better, and perhaps ultimately write a better ending.

A version of this piece appeared originally in SEJournal Online. Reprinted with permission.