I suppose I should begin by introducing myself. My name is Kate Marvel, and I’m a climate scientist at Columbia University and the NASA Goddard Institute for Space Studies. I want to stress that nothing I say here reflects the official view of these institutions, although it damn well should.

My research focuses on understanding climate change past, present, and future. I am incredibly lucky to do this, because, I’ll be honest with you, I have the attention span of a toddler. Climate science is the perfect field for those of us who are easily bored. I get to play with satellite data—pictures we took of the whole planet from outer space—and the output of enormous computer simulations. I’m interested in clouds and trees and plankton and the motions of air and water in the atmosphere. I’m fascinated by volcanic eruptions and wobbles in the Earth’s orbit and the stuff that we humans have dumped in the atmosphere. I am not, however, interested in debating the basic molecular structure of carbon dioxide.

I love this stuff, so it’s a real shame that I spend so much time talking about the aspects of my field that aren’t very interesting. But fine, here you go: carbon dioxide is a greenhouse gas. Burning fossil fuels puts carbon dioxide in the atmosphere. This makes the planet warmer. We have known this for over a hundred years, longer than we’ve known about DNA and internet and second world wars.

Asking a climate scientist whether global warming is real is like asking a physicist how come stuff falls down. We’ve learned things over the past few centuries, and we use these things to ask new and more interesting questions. This is why the collider at CERN is not just a giant inclined plane that people roll things down to see what happens, and why modern chemists do more than mix vinegar and baking soda together (I assume; I don’t know many chemists).

I don’t mean to suggest that there’s no science left to do. After all, I show up to work every day. Some people believe this is because I am engaged in a global conspiracy that has somehow managed to coordinate the actions of scientists, the US military, the finance and insurance industries, most world governments, and, you know, the atmosphere and ocean. Such a conspiracy may exist, but I’m afraid I am not invited to their meetings, which sound much more fun than your average scientific conference and probably have open bars.  But I do my job precisely because there’s still so much to learn about this planet.  

Here’s an example. Barring an asteroid impact, the sudden death of the sun, or the end of industrial civilization, none of which sound like pleasant alternatives, it’s probably going to get hotter. But how hot? We don’t know. This is in large part because we don’t know what people are going to do. Will we cut greenhouse gas emissions, continue on our current trajectory, or evolve toward a Mad Max style dystopia in which the main leisure activity is blowing up fuel tankers? I have no idea.

But even if you remove the uncertainty surrounding human society, we’re still not sure exactly how the planet itself responds to higher CO2 levels. And that’s because warming changes things.  It’s my job to try and understand how these changes then “feed back” onto rising temperatures. Is there a natural planetary defense mechanism- increased cloud cover, for example—that would slow down the warming? Or will the planet throw up its (metaphorical) hands and accelerate climate change, leading us into a dangerous new world?

The answer to this basic question—how hot will it get?—is both certain and terrifyingly unknown. We’re sure it’s not zero; the planet has already warmed by two degrees Fahrenheit in response to human activities. We’re sure that if our greenhouse emissions continue unabated, the temperature will continue to skyrocket. But we’re not sure exactly what’s in store. Will climate change be catastrophic for some or for all? What will it do to the natural world on which we’ve based our civilization? What will the future planet look like? I want to find out.

We—the scientific community—don’t know everything. But we don’t know nothing. We’re surrounded by a world we don’t understand, and I think that wonderful things wait for us in that uncertainty. I want to talk about this beautiful, messy, funny, tragic planet and the terrible, wonderful humans who live here.

But I also want to be clear that climate change is real, and it’s us. I want you to understand how great certainty and great ignorance can coexist with each other. I’m so grateful you’re here, and you’re interested, and you’re reading this. We have something in common already—we’re roommates on the only planet that will have us. I love it here, and I want to know more about it. I hope you do too.