Simon Donner, climatologist

A computer modeler and geographer predicts the future of coral reefs in a changing world, and still manages to get his feet wet. Interview by Jane Palmer

May 25, 2010

Photo courtesy of Finn O'Hara

Simon Donner jokes that his interest in climate arose during his infant days. If he was asleep in his baby carriage, his mother would leave it outside so as not to wake him. As Donner grew up in Toronto, with its famed snowy winters, he often awoke in his carriage under inches of snow. "I guess that is where it all began," he says.

Now an assistant professor in geography at the University of British Columbia, Donner's research focuses on climate variability and how it affects people and aquatic ecosystems. In his most widely recognized studies, he uses computer models to predict the impacts of warming temperatures on a valuable component of ocean life: coral reefs.

Warmer oceans lead to coral bleaching, which harms corals and can eventually kill them. Donner used his models to predict the severity of coral bleaching under different greenhouse gas scenarios, ranging from the "conservative scenario," where carbon dioxide levels in the atmosphere are fixed at 370 parts per million (ppm), to the "business as usual" scenario, where levels rise to 750 ppm by 2100. Not solely a modeler, he also conducts fieldwork in the remote Gilbert Islands of Kiribati, where El Niño events lead to frequent ocean warming.

Donner spoke about corals and climate change at the February 2010 meeting of the American Association for the Advancement of Science in San Diego. Afterward, he chatted with SciCom's Jane Palmer about the plight of corals and the importance of a good old-fashioned gabfest.

How did you first become interested in coral bleaching?

My background was a Ph.D. in atmospheric and ocean sciences, but I had studied a lot of ecology along the way, and I was always kind of fascinated by bleaching. When I started looking at the literature, there hadn't been anyone trying to do the future predictions who really knew how the climate works and how climate models work. So the first step was asking: Can we use the fact that I understand atmospheric ocean dynamics and how climate models work to say what the models really predict for coral reefs?

What are the challenges in using these climate models?

The problem is the models are these big coarse things, and coral reefs are fine and complicated. The climate models are like Lego building-block versions of the world.

Why do you think the work on corals is so important?

Hundreds of millions of people in the tropics depend on reefs: some directly for food and for income, and a lot indirectly for shoreline protection. The loss of reefs as just a simple protective barrier is incredibly important.

Your talk was based on your recent PLoS ONE paper. Can you explain what you did?

We looked at a bunch of different climate scenarios, different emissions and greenhouse gas concentration scenarios for the future, and we evaluated what each of them would mean for the likelihood of bleaching events. We were looking at what time in the future bleaching would become such a frequent event that it is unlikely the corals on a reef would recover.

Were there any surprises?

It almost doesn't matter what the greenhouse emissions scenario would be. In all the different scenarios we ran, the results looked similar.

And they were?

You get to the point where bleaching events become dangerously frequent in 30 or 50 years, pretty much at every coral reef around the world.

"Hundreds of millions of people in the tropics depend on reefs. The loss of reefs as just a simple protective barrier is incredibly important."

Ouch. And you think some of that is because of "committed warming." What do you mean by that?

Water takes longer to heat up and cool down than air does; we know that just from trying to heat water on the stove. As a result, the ocean takes some time to respond to the warming of some greenhouse emissions. We have this lag. Even if we froze the greenhouse gas concentrations in the atmosphere today, the climate is going to keep warming several decades. You can think of that as the commitment. We have already bought more warming than we have seen.

Why is that so important when you are studying corals?

Committed warming is, in itself, a big problem for the world's coral reefs. Assuming we froze greenhouse gas emissions as they were in the year 2000, the model shows the physical commitment alone is enough to cause the thermal stress that causes bleaching at a harmfully frequent rate by the end of the century.

You also predicted what would happen in each scenario if the corals were able to withstand higher temperatures. Can you tell me a little about those results?

There are a lot of potential mechanisms by which corals and their symbionts [the algae that corals depend on] could adapt. We looked at what does it mean if they could adapt by 1.5°C. That's the largest increase in [temperature] tolerance observed in some coral species in molecular studies. If that degree and a half of adaptation were to happen, suddenly you would see divergence between the scenarios. In the scenario in which we stabilize the greenhouse gas emissions at 550ppm, bleaching events are then not dangerously frequent at most of the world's reefs by the end of the century.

So what does this tell us?

If adaptation and acclimation were possible, while it is no panacea, it would buy you time. We'd buy decades, and during those decades, presumably the world could shift from the emissions scenario it is on. None of this is a panacea. It wouldn't mean that reefs would continue looking the way they do, but it is a theoretical and potential way out.

Are you worried that views like yours will make people throw up their hands and give up?

I think we should just do the science. What I have done in the paper is just say here are the numbers. I am not laying judgment about what could be done. I am just saying, here are the numbers.

What is your personal opinion?

People would be surprised to hear this, but I am not that alarmist about climate change, in part because I know the science. My opinion is that we need to mitigate to avoid some of the most disastrous impacts of climate change, but we also need to invest effort in adaptation.

For coral reefs, we need to put a lot of effort into reducing all of the other impacts because it is something we have control over now. I think we need to target our marine protection. As a relative outsider, I don't think the science used in making marine protection decisions is terribly good. We don't think about climate history, and that is incredibly important. Is this place more prone to bleaching events? Is it less likely to survive in the current state for the next hundred years? We have science that can tell us some of that, and we should consider it.

What policy change would you most like to see in terms of the coral reefs?

Sadly, the most important policy change for coral reefs doesn't have a lot to do with the corals or the reefs. It has to do with the climate. It means decisions to see how we can get the world or individual nations on an emissions trajectory that could be more positive for coral reefs, like the ones suggested in our paper. Within the conservation science community, we need to look at marine protection with teeth.

How did people feel about you doing computer models in this field?

Initially people did not receive well what I was saying. That was hard. I don't think that is going to happen so much now that I do this fieldwork in Kiribati. I think it has probably made people realize, "Oh, he actually runs a field project."

How does your fieldwork tie in with your modeling work?

Most coral reefs in the tropics experience a somewhat similar pattern of climate variability—a bit cooler in the winter or warmer in the summer. There is one area which is a big exception, right on the equator in the middle of the Pacific. There, the Gilbert Islands of Kiribati have heat stress more often than other places. The anomalous warmth of the El Niño events really happen quite close to the equator. But somehow those coral reefs have persisted hundreds of thousands of years.

My question was: Can we go there and see what is biologically different?

What have you found?

To be honest, the evidence right now is very anecdotal from our initial surveys. It's a remote part of the world and it's very difficult to work in. It's difficult to find a boat to get out. Due to the safety of diving in the region, I have had to do a lot of the work by free diving. It's just: hold your breath, go down, take a photo with your snorkel on, come back up and do it again.

But I do think there is evidence that there is a difference in the reefs that had higher temperature variability in the past. So there is an interesting story there, but right now the data that we have is pretty preliminary.

How do you try to make people more aware of the implications of climate change and the plight of corals?

Online, I have been doing outreach by posting on my blog, Maribo, writing about climate science, climate policy, and related subjects. I don't know if that is the most effective form of outreach though. So right now I am thinking about different models. Also, I enjoy giving public talks, and most importantly I enjoy speaking to students. If you are ever feeling down about the prospects for tomorrow, go talk to a bunch of high school students. They are impressive.


They have energy that our generation and the generations before me are not going to have. They are a great audience.

What sort of other types of outreach are you thinking of doing?

I think because so much of our communication and interaction has moved online, people are actually craving just old-fashioned firsthand interaction and storytelling.

I know in Europe there has been a bit of an increase in the café culture, the idea of having a science café once a week at the pub. I think there is a real possibility in the future for things like that. It is almost a backlash against the Internet. "I don't want to read about this online, I want to sit around with people in my community and see what they think." Radical idea!

Jane Palmer, a graduate student in the Science Communication Program at UC Santa Cruz, earned her bachelor's degree in cognitive science and her Ph.D. in computational molecular biology, both from the University of Sheffield, U.K. She has worked as a reporting intern at the Monterey County Herald and the Santa Cruz Sentinel. This summer, she will be a science writing and multimedia intern at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder.

© 2010 Jane Palmer