When it comes to global warming, Yadvinder Malhi, a leading tropical biologist from Oxford University, said he’s confounded by how the United States has transformed what is essentially a complex scientific issue into a battle of partisan politics.
“In the UK, you can be right wing or left wing and still take climate change seriously,” Mahli told me in Peru recently. “From the outside looking at the United States, it seems a part of the culture wars. You have to wear a certain set of ideologies, and climate change is one of the ideologies you wear depending on your party affiliation. Why can’t we just look at this subject on its own merits and weigh the evidence and what to do?”
Often it seems the nature of scientific inquiry and debate — the challenging of carefully gathered data, the arguments over preliminary conclusions — give skeptics the opportunity to surmise: if the scientists can’t agree, why should we believe them?
Embedded with two tropical biologists in the Amazon basin of the Andes in southern Peru, I observed them as they visited about 10 of their jungle research plots. During a break in one of our many arduous downhill hikes, packs full and weighed down with camping gear, I got some answers to questions I'd been hoping to ask.
I was with biologists Miles Silman of Wake Forest University and Ken Feeley of Florida International University, who along with Malhi, are members of the Andes Biodiversity and Ecosystem Research Group. They argue that while there is much debate about climate change in the scientific community, there is little disagreement about the most pressing issues:
Do other scientists challenge you on the fundamental aspects of your work — that tropical forests are under stress from rising temperatures and struggling to adapt?
Miles Silman: No, but we challenge each other a lot on the details. Where it will happen? What will the magnitude will be? What are the time scales? What comparisons will we use with the past? We fight about those things all the time. And we fight with data.
Ken Feeley: It is the basic physics and laws of thermodynamics that define a lot of climate change. Things that we simply can’t deny. There’s no way we can really argue over those points. But there is a problem in the literature that people can view our internal debates and conclude there is not consensus among us. People can argue over whether plants are going to benefit under increased CO2 or whether are they going to be hurt by rising temperatures, and which effect is stronger. These are all relatively small details compared to the large-scale trends that we’re seeing.
Some see a real upside to these warming trends. Growing seasons in northern climates, for example, are getting longer. More higher-latitude land is becoming suitable for farming.
MS: Yeah, you can move crops northward. Canada can be more productive, assuming the soils can handle it. So productivity will increase in the higher latitudes, but it won’t at the southern ones. One of the problems is, things might be a little bit better at high latitudes, but is it fair to do that on the backs of all these people in the low latitudes? If you look at places where crop yields are projected to decline, it’s in some of the poorest and most populated places in the world. All of central Africa. Then when you look into India, those crops yields are predicted to go down a lot. There’s a billion people living in India. When you look at the warming projections when we get out past 2100, the crop yields, except for the highest latitude lands, are going down.
KF: If you look at North America and Europe, we’re already maxed out on agricultural yields. Big corporate growers have incredibly efficient systems. They use lots of fertilizers and pesticides and herbicides. They have 100 percent yields. When you think about where food needs to come from in the future, it’s going to have to come from the tropics. But that creates another problem. Deforestation, which contributes to global warming. Eighty percent of new cropland each year is coming from tropical deforestation. We have a lot of mouths to feed, and climate change creates an extra hurdle that we have to get over to create that food supply.
You two published the first paper in 2010 that argues that tropical species are migrating up-slope as the result of rising temperatures. I look around, and to me, these forests seem resilient and adaptive.
MS: That’s true, to an extent. The species here have an upper limit on how far they can go. We see things are shifting up from the lower elevations. But there’s nothing coming out of the ocean to occupy the lowlands when the temperatures get warmer. The things in the lowlands can move up into the mountains, but what fills in behind them? So, as we see it, either the trees have a broader temperature tolerance than we can observe, and when the temperatures warm we’re going to see the rest of their niche that we haven’t seen before. Or you’re going to have apocalyptic population reductions and extinctions in the lowland forests. We can’t answer that question.
MS: It’s a very complicated problem. We’re just starting to do the most basic experiments. We can take a seedling and put it in a chamber and warm it. We can see if it can live or die at what temperature. But that doesn’t incorporate the natural enemies. Look at these plants around us. There are funguses on the leaves, insects eating them alive. In the soil there are wars going on all the time. Replicating that in an experiment and incorporating that meaningfully into a demographic prediction – drought, monsoons, rising temperatures – it’s a monumental challenge.
There are a lot of unanswered questions regarding some very basic biological issues. How are policy makers supposed to make decisions to stem global warming in the absence of what seems like a lot of critical information?
MS: You can do two things in order to make a decision. You can say, ‘Well, I need more information about how exactly these details are going to work.’ Or, ‘No matter what the future outcome, I’m going to structure decisions now so that it’s beneficial to us.’ Most people have the wrong idea of drilling down and saying, ‘I want to know which tree is going to die where.’ Rather than saying, ‘How are we going to start structuring land use so that we don’t experience these very worst outcomes?’ I think we already know a lot about what we need to do. And do it in ways that don’t have negative economic implications.
I think there’s a third choice: ‘This is all too complicated so I’m just going to ignore it.’ I think that that’s where a lot of policymakers are these days.
MS: I don’t think that’s acceptable. There are many moving parts, but that doesn’t mean we don’t know what levers to press. Here’s what we do know now: You need to keep the temperatures from going too high. You need to protect large tracks of forest to allow for species migration. And you keep intact the animals, birds and insects that make a forest a forest. We’re done. We walk away.
Why do we need to do all that?
MS: So that we have an earth that has the same ecosystem services and biodiversity and the ability to explore new drugs and agriculture and things that we’ve had throughout our civilization. If not, we move the world into a state where, you know, we’ve never experienced before. And then we have enormous negative consequences for everyone.
Most people believe that those effects, if they are even true, are a long, long way off.
MS: They’re not. It’s not decades away. It’s right now. Crop yields are going down. You can see trees moving. And we know it’s going to get worse.
KF: In many ways, we have been able to distance ourselves from this issue in the United States. You turn up the air conditioning. You handle a slight price hit on food at the grocery store. But it’s the people who are living at the margins, which is the majority of the world’s population, who are already feeling these things. If you look at where climate-change deniers are, they don’t live in Third World countries. Here in Peru, everyone is very much on board with the idea that climate change is happening and it’s something to be concerned about. There’s no climate denial here.