How effective is data at predicting environmental change?

This weekend marked the start of COP26, the United Nations climate conference in Glasgow, Scotland.

It’s viewed by many scientists as a last-chance opportunity to coordinate the management of climate change on a global scale. The commitments made by countries this week could determine what the world will look like in a few decades. Those countries are turning to advanced climate models to imagine that world.

I asked Zeke Hausfather, a data scientist and the director of climate and energy for The Breakthrough Institute, how those attending COP26 will be using climate models in their negotiations. The following is an edited transcript of our conversation.

Zeke Hausfather: Climate models are one of the most important ways that we can understand how the climate might change in the future, as well as how it’s changed in the past. They give us a sense, both of what sort of warming will happen at the global level if we keep increasing our emissions, or if we produce them, for that matter, and what will happen for specific regions and countries over the course of the century. So they play a big role in informing a lot of our estimates of the damages of climate change, all the bad stuff that happens, be it sea-level rise, more tropical cyclones or more intense tropical cyclones, wildfires, and all the other nasty things that come with a warming world.

Kimberly Adams: How has the accuracy of the models changed over time?

Hausfather: Nowadays, we actually call them Earth System Models rather than climate models, because they include a model of the Earth’s vegetation. You can see how areas covered with trees and grasslands change as the planet warms. So you can look at how those then affect the carbon cycle and how much of our CO2 emissions remain in the atmosphere. These interactive effects that you get by coupling different systems are a really important part of modern climate modeling. A lot of our advances over the last 50 years have been including more and more modules of the Earth’s systems and seeing how they interact together. Back in the 1970s, we were essentially simulating the planet as like, one column of atmosphere, with ocean at the bottom and sky at the top. We went from modeling the world as single column to 500 kilometer-square boxes, 200 kilometer, 50 kilometer. Nowadays, we have 25-kilometer-high resolution model-runs. As you increase the resolution of these models, you can do a better job of resolving smaller scale processes that just would not really show up in less finely tuned or grained models.

Adams: Wow, that’s a really amazing progression.

Hausfather: Yeah, well, there’s a reason why a lot of the world’s fastest supercomputers are used for climate modeling these days. It takes years of time and many groups around the world and many, many supercomputers to get all these modeling results done.

Adams: COP 26 is upon us. And it means that countries will be meeting and making decisions about their commitments to fighting climate change. What will you be looking out for at this meeting?

Hausfather: A lot of countries over the last few years have finally started to make long-term commitments to get their emissions to zero by the middle of the century. And so coming into COP[26], a big question people have is: How much will we see these long-term commitments being translated into stronger near-term pledges to actually do stuff by 2030, for example? And we’ve seen some countries give stronger pledges — the EU, the U.S., for example. Others, like China, have been much less willing to make strong near-term commitments.

Adams: You spend so much time steeped in this data about how the Earth is going to change in the coming decades, and you also have a family. How worried are you? How do you think about all this?

Hausfather: It’s definitely something I’m worried about, you know, particularly living in California, where we see the impacts of climate change very front and center with our exceptional wildfire seasons. But at the same time, in some ways, I’m actually a little more hopeful now than I was five or six years ago. Like, I don’t think we’re gonna end up in the best of all worlds. I think we’re gonna have a really hard time limiting global temperatures to below 1.5 degrees Celsius since we’re [on track to warm by] at 1.2 degrees Celsius today, and that’s just such a small margin. But I think, given how quickly clean energy technology prices have fallen, given how countries are finally starting to make some more meaningful commitments, even if it’s not enough, I think we have a real shot at limiting warming to below 2° Celsius by the end of the century in a way that we didn’t five years ago. We’re probably gonna end up in a world that’s not the perfect world, but not as catastrophic as it could be if we continue to take action on it, if we push politicians as hard as we can. And you know, that’s not the world I want to leave my daughter. But that’s a lot better than the world that we could be leaving her.

Related Links: More insight from Kimberly Adams

Hausfather recently wrote a detailed article laying out what climate models can and can’t tell us about what’s ahead for our changing climate. In it, he gets into some of the results from the recent report from the Intergovernmental Panel on Climate Change. There is grim news for what’s ahead in the report, Hausfather says, but reason for hope.

If want to learn more about how climate models work, the National Oceanic and Atmospheric Administration has a guide on how such models are made, tested and used.

And National Geographic has a piece how climate modelers are finding themselves in kind of in a moment, including a Nobel Prize in Physics.

And here’s a Bloomberg article setting up the COP26 meetings. It has some interactive charts showing how previous climate summits have affected global emissions, and what the stakes are this time around.