Where Will Earth Head After Its ‘Climate Departure’?

Will the planet reach a point where its climate is significantly different from what has existed throughout human history, and if so, when? In an interview with Yale Environment 360, biogeographer Camilo Mora talks about recent research on this disquieting issue and what it means for the coming decades.

The term “climate departure” has an odd ring, but its meaning is relatively straightforward. It marks the point at which the earth’s climate begins to cease resembling what has come before and moves into a new state, one where heat records are routinely shattered and what once was considered extreme will become the norm.

Camilo Mora — a University of Hawaii biogeographer, ecologist, and specialist in marshaling big data for climate modeling — has calculated a

Camilo Mora
Camilo Mora
rough idea for the time of the earth’s climate departure: 2047. That date varies depending on region, he says. But in a widely publicized paper published in the journal Nature last year, Mora and 13 colleagues explored the concept of climate departure and what it will mean for our planet.

In an interview with Yale Environment 360 contributor Diane Toomey, Mora explains why tropical regions will be most profoundly affected by climate change, why controlling population growth is at the core of the challenge posed by global warming, and the frustrations he and other scientists feel as their warnings about rising temperatures are repeatedly ignored.

Yale Environment 360: You and your team made headlines when you published a paper in Nature that examined the timing of climate departure. Please define that term.

Camilo Mora: The timing of climate departure is an index that calculated the year after which the climate will become like something that we’ve never seen. We calculated the minimum and maximum values for the historic variability in the last 150 years. And we analyzed when climate change is going to move the climate beyond those thresholds. At the broadest scale, we calculate that year, under a business as usual scenario, is going to be 2047. Basically, by the year 2047 the climate is going to move beyond something we’ve never seen in the last 150 years.

e360: The results of your analysis were startling, I think, even to you and your team. Under the scenario that assumes current emissions trends, part of Jamaica and Indonesia are just a few years away from climate departure; you predict Mexico City will experience this in 2031. To carry out your analysis, you used 39 climate models. Talk a bit about how big your big data was.

Mora: We analyzed all the earth system models that are available. Regarding climate, we analyzed 39 earth system models. Every model

Journal Article Challenges
Mora on Climate Departure

Thirteen climate scientists and meteorologists have published a sharp criticism of the paper in Nature by biogeographer Camilo Mora, which calculated dates when the earth’s climate will move into a new state caused by global warming. In a comment published in Nature on July 3, the 13 scientists say Mora and his colleagues used faulty methodology that produced artificially early dates when specific regions would reach “climate departure.”
covered about 200 years, and every year had data from 60,000 locations around the world and all of that for each of 12 variables. We’re talking on the order of 5 billion points of data just on climate. We also analyzed how that is going to influence biodiversity and people. The paper is unique in how it integrates data from climate, biological, and socio-economic systems. Of course, there was some variability in the models but the general trend really was very remarkable in how similar it was.

e360: Your results regarding the tropics were particularly disturbing.

Mora: When you think about climate change, people usually think about the poles, the reason being that the largest changes in temperature are going to occur at the poles. However, what we found is that the timing of climate departure will actually occur sooner in the tropics. The reason for that is that the tropics have a very small variability. So it’s very easy for climate change to move the climate in the tropics beyond anything that the tropics have seen. And of course the biological implications for these things are massive, because in the poles the species are already adapted to variability in the climate. Think about the winter and the summer and the changes in temperature. All of the species that live there are already adapted to that variability. In the tropics, the species are adapted to a very stable climate. So as soon as you move the climate beyond the variability, all the species in the tropics are going to suffer quite dramatically. And we already have evidence of that. Coral reefs are a good example of that. If you increase the temperature by just one or two degrees, there is massive bleaching and coral mortality.

e360: You and your team used the years from 1860 to 2005 to establish the historical range of five climate variables. But since the later part of that time period contains a human climate change signal, climate departure may happen much sooner than the years you and your team calculated.

Mora: Indeed. One [key] variable was pH, which is completely off the charts already, completely outside the historical variability. The reason being is that the oceans are taking up a huge chunk of the CO2 that we are producing and that is acidifying the oceans beyond anything that those animals have seen for millennia.
“As scientists, we are struggling to figure out how we can increase public awareness on this issue.”

e360: The publication of the paper was widely covered in the general press. What were your hopes for the paper in terms of climate policy debate?

Mora: From a scientific point of view, climate change is something that is very certain. When you go and do the analysis on this data and you look at temporal trends, you realize that for us there is no doubt that we are changing the climate of our planet. And of course, I think my motivation and everybody’s motivation whenever we produce these papers is trying to increase the level of awareness of people and politicians to take action on these things.

e360: Have you seen any evidence of that?

Mora: Not really. You don’t see any action on these things. And the problem is that these things die away pretty quickly. The press coverage of this paper lasted two days. We were in the New York Times, The Washington Post, CNN. And next week, people were talking about something else. So as scientists, we are struggling to figure out how we can increase public awareness on this issue.

e360: You prepared for months on how to communicate the results of this work. How did you prepare, and what was the goal of that training?

Mora: The analysis that went into the paper took us six months altogether, from the time that we came up with the idea to the time when we sent the paper out. However, the actual writing of the paper took us about two months. It’s 40 pages altogether. But it’s amazing that the press release on this paper took us two months to prepare. It was a massive investment of time for just two pages of paper. So another limitation for us as scientists is that it’s very hard for us to commit that kind of time to prepare for that press release.

e360: I imagine it’s highly unusual to train on how to communicate the results of one’s work.

Mora: I have a Ph.D. I’ve taken hundreds of courses for my undergraduate degree and my Ph.D., but I never took a class in how to communicate science to the general public. Even now, if you look around at the curriculum in universities, you don’t see any training in the sciences in how to communicate to the public. And sometimes we miss opportunities. Sometimes I see scientists being interviewed on television and there’s a scientist being hammered by politicians and interest groups, people who are better trained and know better how to talk to the public. We miss these
“When we start damaging the capacity of physical systems to produce food, people will react in a terrible way.”
opportunities to communicate science to the public just because we don’t have the training for it.

e360: You specialize in using big data to analyze environmental issues. What drew you to large-scale analysis?

Mora: What drives me is actually globalization. If you look at economic metrics, those metrics are collected globally. What is remarkable is they are even collected daily. But we don’t have that kind of monitoring for any environmental variable.

And the problem is changes are happening in places and people can’t appreciate the magnitude of these changes until it is too late. There are multiple cases of species that have gone extinct and the laws to protect those species come years after the species went extinct. And that’s what drives me to do these large-scale analyses, to be able to deliver these broad-scale results that allow you to see the magnitude of the changes we are causing.

It’s one thing if you are cutting a tree. It’s completely different if you are cutting trees everywhere around the world. Six million hectares of forest are cut every year. You cannot get those numbers without doing it globally.

e360: You’re speaking to me now from your home country of Colombia. How does the fact that you’re from a developing country inform or inspire your research?

Mora: I grew up in a country where there has been a long history of violence. We have been in war for 50 years, and one thing people don’t realize is what it means to be in a place where anyone can get shot at any moment, where people are starved to death, where there is not enough food to feed people. In the first world, people don’t know how rich they are,
We’re on our way to some very disturbing scenarios if we go down this pathway of damaging physical systems.”
and they don’t realize what is happening in the rest of the world. And for me that’s a driving force. It’s scary to think about climate change because when we start damaging physical systems and the carrying capacity of physical systems to produce food, people will react to this in a terrible way. I’m telling you, I have seen it in my own country. It’s very negative the way in which people react to hunger. And that’s one of the things that’s most frightening to me with this large-scale analysis — the fact that I know we’re on our way to some very disturbing scenarios if we go down this pathway of damaging physical systems in the ways that we are today.

e360: You’ve been outspoken on the issue of overpopulation. In a paper you published earlier this year in the journal Ecology and Society, you referred to the issue as fundamental, but fading from public consciousness. Why, in your estimation, is this issue so paramount?

Mora: Well, it’s paramount because people need food. And the planet is limited in the amount of resources that it can produce. We already have calculated that the planet has on the order of 11 billion hectares that can be harvested in a sustainable manner. Of course we can increase the number by increasing technology, but that’s been happening for the last three decades. The worldwide population is 7 billion people, and we know that to sustain a human being you need on the order of two hectares per person. That means that the world human population every year consumes on the order of 14 billion hectares. The planet only has eleven to give to us. Every year, we consume in excess of three billion hectares. What I’m suggesting is to inform people about the environmental and social costs of


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having a child. And for governments to allow people those choices. Today we have on the order of 200 million women who want access to family planning that don’t have it. So for me the solution is right there.

e360: In a paper in Ecology and Society, you were quite critical of the conservation biology community and the Intergovernmental Panel on Climate Change for not talking about the issue of overpopulation. Why, in your estimation, don’t they talk about this issue? What is holding them back?

Mora: It’s pure fear. It seems amazing, but friends of mine recommended to me not to publish that paper. They said, “This paper is going to be damaging to you. You don’t get it. You don’t need it.” What is remarkable, though, is that after the paper got published, I had multiple people calling me to endorse it.

e360: Did they endorse it publicly?

Mora: No, just to me. This is really the problem. But why we don’t take it on? I have no clue. Because the data are very clear. I guess the problem is that it can backfire. We have seen, historically, situations in which a scientist has taken on an issue and there are people who have been fired, or attacked by interest groups. So I guess the problem is fear of retaliation.