Mangos are on the move.
A recent story on the online news site Grist reported from the Italian island of Sicily, where growing conditions are becoming more favorable to tropical mangos than to the lemons and olives traditionally grown in the region.
For longtime readers of Conservation News, this may come as little surprise.
In 2020, Conservation International scientists published research predicting how the “farming frontier” would shift in our climate future — enabling humans to, pardon the expression, boldly farm where no one has farmed before.
The study’s lead authors, Lee Hannah and Patrick Roehrdanz, spoke with Conservation News last week about what it feels like when “insane” climate predictions start to come true.
Conservation News: I want to start back in 2013, when you published a study predicting that wine growing was going to change drastically because of climate change. It caused a big splash at the time.
Lee Hannah: Yeah, when Patrick and I worked up the first models [for that research], we thought it was insane, because it said that the suitability for growing wine grapes would improve in places like Tasmania and central China. And people were asking us, Was that even realistic? And as we’ve seen, it was realistic: Tasmania is a booming wine region now — I just got back from Australia, and Tasmanian wines are all over in the stores.
CN: So then a few years later, you published this agricultural frontiers research — for people who might not know, what was the main message from that?
Roehrdanz: The big news for agricultural frontiers was — at a global scale — the sheer amount of land that would become available for farming in the Northern Hemisphere that had previously been unsuited for farming. Because most of those areas are forested, the environmental consequences of farming there could be really bad, to say the least.
Hannah: But at the local scale there was big news in the tropics too – that’s what the Grist story was talking about.
CN: About the mangos story: What was your gut reaction when you read it? As a scientist, did you feel validated?
Roehrdanz: As I read the mangos story, I thought, Yeah, it seems crazy — but also totally in line with what we expect to be happening at this point. Not that we're necessarily pleased to be proven right! There will always be uncertainty involved with any projections of climate into the future, but real-world validations such as this story affirms that this work can paint a picture of what's possible.
CN: Speaking of tropical fruits: Your research really hammered home the idea that these northern latitudes were going to change. But what happens in the tropics? What were you seeing there?
Hannah: On the tropical side of things, our research showed that the movement of tropical crops was more regional and local than other crops, because they’re pre-adapted to warmth. But at local scales those changes could be dramatic and life-altering for farmers, as the story in Grist pointed out.
Another one of the things we looked at was agriculture shifting to find cooler areas as temperatures rise. And in the tropics, that’s going to happen on mountain slopes. You can fly over Bogotá, Colombia, and see it playing out in valleys going up the Andes. There's what they call the “green gap” in the Andes, which is the area that's been cleared of forest because it is suitable for agriculture — too warm and disease-ridden below, too cool above.
And you've got a band of clearing for agriculture, because that's where it's suitable for growing crops. Well, that green gap is going to be moving up.
Roehrdanz: If you look at the global map [in the agricultural frontiers paper], that tropical story doesn't really jump out, which is why I often say it's a hidden story. The big changes in the north jump right off the map at you, but the stuff going on in the tropics is happening in valleys, or individual mountain peaks, or ranges, and so it's not really going to look dramatic on a global map.
But if you zoomed in on any one of those tropical areas, there would be big changes — and not just for farming. They would also have serious consequences for biodiversity. You know, for us, when we were conducting this research, we were less interested in the agricultural aspects and more concerned with the ecological ones. We live in a world that's increasingly crowded, and when agricultural areas are expanded, you lose space for wildlife.
There are surveys in the Andes where they see birds that are just disappearing off the tops of mountains; it has been called the “escalator to extinction.” They go back to resurvey, they see all the same birds they saw, they're just bumped up a little higher up the mountain slope — except for the ones that were at the top of the mountain. They're never seen again. That’s going to keep happening, and we see it in other animals too, notably frogs.
CN: What's been the legacy for your research up to this point?
Roehrdanz: To use the worst mixed metaphor ever, it's definitely snowballing. People growing crops are tuned in to climate. You know, when we did the wine and climate paper, it was sort of the unspoken secret of the wine industry that this was all going to be happening. Now we see it happening across all sorts of crops.
Hannah: Right, farmers are super tuned-in to climate and are adjusting accordingly. Mangos in Sicily — who knew? Unfortunately, beyond that, I don't see a ton of awareness at the policymaker level. We need to plan for this, or it will hurt us.
Changing crop suitability will affect farmer livelihoods and scramble food production landscapes in ways that may hurt nature conservation. For instance, if Canada keeps promoting agriculture in the far north indiscriminately, it could lead to huge loss of forests and world-altering carbon emissions. In the tropics, the escalator to extinction could become the “elevator to extinction” as crops moving upslope erode the bottom of forest habitats while upper-level species are disappearing off the tops of mountains.
Policymakers need to start listening to farmers and conservationists — they need to get policies and planning in place to anticipate these changes.
Bruno Vander Velde is the managing director of storytelling at Conservation International. Want to read more stories like this? Sign up for email updates. Also, please consider supporting our critical work.
