Being a climate scientist

If there was one message I’d give to people, it’s the importance of not succumbing to black and white thinking, or – because I work in polar climate change – what you might call "polar thinking". We live in a world that is increasingly polarised. We have different groups that fight each other politically and culturally. That often spills into the way that we see science, scientific expertise and scientific predictions as being 100% right or wrong, or a particular future as being 100% good or bad. This simplistic way of thinking is very seductive.

It’s understandable that humans do this. It’s quicker than thinking about the nuances and the complexities. It’s something we do when we’re faced with uncertainty or fear. Our natural instinct is to simplify, to put up boundaries and to exclude the people we think don’t agree with us. We say that they’re “other”, that they’re wrong and perhaps evil or morally bad.

But we have to resist that human instinct to simplify and polarise. We have to take the time to look at the detail, to look at the nuance, to understand. It’s time-consuming. It’s hard. You put yourself at risk when you try to judge each event on a case-by-case basis: you might be wrong. And it’s so much easier to retreat into name-calling or certainty and dogma. But now, more than ever, we have to look at the subtleties of every situation. We have to be able to say: For the most part, I don’t agree with this person. But on this thing, they might be right. They’re not simply a "bad" person or a "wrong" person.

With science or scientific expertise, there’s not really any such thing as a good scientist or a bad scientist in that sense, or a right scientist and a wrong scientist. There are always degrees of how well studies are carried out and how certain they are. When we’re at the cutting edge of a particular part of scientific research, then things are going to be a bit fuzzier and more uncertain. As we gather more evidence, things tend to become clearer and more certain. That can sometimes even contradict the early findings, because we’ve learned more.

We shouldn’t ever be afraid of changing our mind in that way, because the evidence evolves and our understanding evolves. The same is true for predictions. We see in the news, for example, different scientific climate predictions. And we say: last week they were saying one thing, and this week they’re saying something new. They should just make up their minds. And I’ll just wait until they make up their minds. Or we think that they don’t know anything, or that these guys know what they’re talking about and those guys don’t.

Science is always going to be uncertain at the cutting edge. You will always get studies and predictions that are different because we are at the tentative boundaries of knowledge. People are putting ideas out there that are plausible but have a limited amount of evidence to support them. And other people are doing the same thing and they’re going to say slightly different things. But eventually, over time, we gather more evidence, we gather more understanding, and we converge.

This is particularly difficult in something like climate change, because we’re making predictions far into the future, which we won’t be able to verify for decades to come. And even then, it’s difficult to verify them because our exact pattern of future greenhouse gas emissions might not be the ones that we made predictions for today. So, even in 50 or 100 years, if someone were to look back on the predictions that I made for sea-level rise, the process of deciding whether I was right or wrong is really about the balance of probabilities, and also needs to account for the exact emissions we produced.

At times it makes your head hurt. But it’s so important to keep persisting, to keep asking questions. Why do those studies differ? Why do those predictions differ? Why do people disagree? Why do things seem to be complicated? We can’t just give a nice, simple answer. We have to keep asking why. It’s only by doing this that we can understand that different scientists use different methods and assumptions; that they write different computer models with slightly different approaches; that people interpret data in different ways.

There isn’t a single objective recipe for how to interpret data. There’s always a human involved. As scientists, we’re searching for patterns in data, and we might see different patterns and come to different conclusions. Of course, those conclusions tend to be in the same general direction, but the details will be different. And we have to understand what it is that’s making those predictions or those interpretations different.

It would be a mistake to succumb to polar thinking, to a reductionist way of looking at the world in which everything is purely good or bad, or purely right or wrong. That’s rarely the way the world is. There’s always a spectrum. There are always degrees. And that’s not a weakness or a problem. It’s the way that the world is. It’s the way that knowledge works. It’s the way that science works. It’s the way that humans work.

And, in fact, I’m suspicious of anyone who’s incredibly certain about something, or deeply simple and clear in the way they communicate something, unless they also acknowledge that there are other complexities involved: that they’re simplifying the story for now, but there’s more to it. That isn’t hedging. It’s not a problem. We’ve somehow absorbed this idea through our culture that changing our mind is bad; ambiguity or uncertainty is bad; saying that things are shades of grey in a spectrum is bad. It’s not. It’s good, and it’s important. The most important thing is to acknowledge that the world is complex and there are no easy, simple answers.

What’s worrying about this new idea of instability that relates to ice cliffs is that it could be extremely rapid. Melting and glacier flow are somewhat limited in how fast they can happen. If you have a great glacier of ice flowing into the ocean, calving off icebergs, contributing to sea-level rise, that can become faster, but it’s never going to become very fast. But the idea of the marine ice cliff instability is that the edge of the ice sheet could crumble rapidly into the ocean. That would lead to much faster sea-level rise than any of our previous predictions.

To give a sense of scale, the upper end of sea-level predictions under high greenhouse gas emissions is around one metre this century, maybe a little more. But if the predictions come true for this ice cliff instability, just that extra contribution from Antarctica alone could double the total sea-level predictions to two metres or more. So, the consequences of this hypothesis are enormous if they come about. But there’s huge disagreement in the community about how likely this is and how it would happen.

The original paper made these worrying predictions of rapid sea-level rise. But others, including myself, have looked again at the data, and we find that there is evidence that the sea-level rise would be much slower than those catastrophic predictions. There isn’t really that much direct evidence that it would even happen at all. However, I’m not confident enough to completely rule it out. I’m not saying that the marine ice cliff instability is completely impossible, but it’s about the balance of evidence.

In climate change, we have people working at different timescales. Climate scientists are making predictions for the end of the century or even for many centuries beyond, while people on the ground are making plans for how flooding will change in the next few decades based on the information that we have now; they can’t wait a few decades for better information. There are people living with extreme weather today, and they want to know how that might change in 10 or 20 years. What storms might we have? What droughts? So, there are these parallel tracks of people who need to make decisions now, knowing that we will never be certain about everything. Meanwhile, climate scientists are continuing to work to refine our understanding and reduce those uncertainties, because there’s still value in that. In 10 or 20 years, it will still be useful to try and pin down those uncertainties while we change as a society.

On the other hand, if we lose large parts of the Greenland and Antarctic ice sheets and the mountain glaciers, that’s not reversible on meaningful human timescales. It takes much longer to grow an ice sheet than to lose it. For example, we might lose large parts of Greenland or West Antarctic ice sheets in 200 or 300 years. But it can take 1,000 years of snow falling on an ice sheet to gain just 2 metres of ice thickness. It’s very slow to build an ice sheet through snow, but losing an ice sheet can be a very rapid process. We can just lose chunks of it into the ocean as icebergs. The ocean can erode the ice sheet from underneath in a much faster way than snow can build it up.

And if we lose parts of the ice sheets, that would take millennia to replace. It would take many generations of humanity. We have to think about that, not only in terms of the consequences for our coastlines, our cities and our way of life around the world but also in terms of the moral consequence. What a responsibility to have, as our generation, to be the ones who lose great parts of the ice sheets that would take thousands of years to return. And those aren’t the only examples of, effectively, irreversible change in climate change. But they are some of the most resonant.